Gardening Without Irrigation: or without much, anyway
by
Steve Solomon
Part 1 out of 2
Created by: Steve Solomon ssolomon@soilandhealth.org
Cascadia Gardening Series
Gardening Without Irrigation: or without much, anyway
Steve Solomon
Introduction
Starting a New Gardening Era
First, you should know why a maritime Northwest raised-bed gardener
named Steve Solomon became worried about his dependence on
irrigation.
I'm from Michigan. I moved to Lorane, Oregon, in April 1978 and
homesteaded on 5 acres in what I thought at the time was a cool,
showery green valley of liquid sunshine and rainbows. I intended to
put in a big garden and grow as much of my own food as possible.
Two months later, in June, just as my garden began needing water, my
so-called 15-gallon-per-minute well began to falter, yielding less
and less with each passing week. By August it delivered about 3
gallons per minute. Fortunately, I wasn't faced with a completely
dry well or one that had shrunk to below 1 gallon per minute, as I
soon discovered many of my neighbors were cursed with. Three gallons
per minute won't supply a fan nozzle or even a common impulse
sprinkler, but I could still sustain my big raised-bed garden by
watering all night, five or six nights a week, with a single, 2-1/2
gallon-per-minute sprinkler that I moved from place to place.
I had repeatedly read that gardening in raised beds was the most
productive vegetable growing method, required the least work, and
was the most water-efficient system ever known. So, without adequate
irrigation, I would have concluded that food self-sufficiency on my
homestead was not possible. In late September of that first year, I
could still run that single sprinkler. What a relief not to have
invested every last cent in land that couldn't feed us.
For many succeeding years at Lorane, I raised lots of organically
grown food on densely planted raised beds, but the realities of
being a country gardener continued to remind me of how tenuous my
irrigation supply actually was. We country folks have to be
self-reliant: I am my own sanitation department, I maintain my own
800-foot-long driveway, the septic system puts me in the sewage
business. A long, long response time to my 911 call means I'm my own
self-defense force. And I'm my own water department.
Without regular and heavy watering during high summer, dense stands
of vegetables become stunted in a matter of days. Pump failure has
brought my raised-bed garden close to that several times. Before my
frantic efforts got the water flowing again, I could feel the
stressed-out garden screaming like a hungry baby.
As I came to understand our climate, I began to wonder about
_complete_ food self-sufficiency. How did the early pioneers
irrigate their vegetables? There probably aren't more than a
thousand homestead sites in the entire martitime Northwest with
gravity water. Hand pumping into hand-carried buckets is impractical
and extremely tedious. Wind-powered pumps are expensive and have
severe limits.
The combination of dependably rainless summers, the realities of
self-sufficient living, and my homestead's poor well turned out to
be an opportunity. For I continued wondering about gardens and
water, and discovered a method for growing a lush, productive
vegetable garden on deep soil with little or no irrigation, in a
climate that reliably provides 8 to 12 virtually dry weeks every
summer.
Gardening with Less Irrigation
Being a garden writer, I was on the receiving end of quite a bit of
local lore. I had heard of someone growing unirrigated carrots on
sandy soil in southern Oregon by sowing early and spacing the roots
1 foot apart in rows 4 feet apart. The carrots were reputed to grow
to enormous sizes, and the overall yield in pounds per square foot
occupied by the crop was not as low as one might think. I read that
Native Americans in the Southwest grew remarkable desert gardens
with little or no water. And that Native South Americans in the
highlands of Peru and Bolivia grow food crops in a land with 8 to 12
inches of rainfall. So I had to wonder what our own pioneers did.
In 1987, we moved 50 miles south, to a much better homestead with
more acreage and an abundant well. Ironically, only then did I grow
my first summertime vegetable without irrigation. Being a low-key
survivalist at heart, I was working at growing my own seeds. The
main danger to attaining good germination is in repeatedly
moistening developing seed. So, in early March 1988, I moved six
winter-surviving savoy cabbage plants far beyond the irrigated soil
of my raised-bed vegetable garden. I transplanted them 4 feet apart
because blooming brassicas make huge sprays of flower stalks. I did
not plan to water these plants at all, since cabbage seed forms
during May and dries down during June as the soil naturally dries
out.
That is just what happened. Except that one plant did something a
little unusual, though not unheard of. Instead of completely going
into bloom and then dying after setting a massive load of seed, this
plant also threw a vegetative bud that grew a whole new cabbage
among the seed stalks.
With increasing excitement I watched this head grow steadily larger
through the hottest and driest summer I had ever experienced.
Realizing I was witnessing revelation, I gave the plant absolutely
no water, though I did hoe out the weeds around it after I cut the
seed stalks. I harvested the unexpected lesson at the end of
September. The cabbage weighed in at 6 or 7 pounds and was sweet and
tender.
Up to that time, all my gardening had been on thoroughly and
uniformly watered raised beds. Now I saw that elbow room might be
the key to gardening with little or no irrigating, so I began
looking for more information about dry gardening and soil/water
physics. In spring 1989, I tilled four widely separated, unirrigated
experimental rows in which I tested an assortment of vegetable
species spaced far apart in the row. Out of curiosity I decided to
use absolutely no water at all, not even to sprinkle the seeds to
get them germinating.
I sowed a bit of kale, savoy cabbage, Purple Sprouting broccoli,
carrots, beets, parsnips, parsley, endive, dry beans, potatoes,
French sorrel, and a couple of field cornstalks. I also tested one
compactbush (determinate) and one sprawling (indeterminate) tomato
plant. Many of these vegetables grew surprisingly well. I ate
unwatered tomatoes July through September; kale, cabbages, parsley,
and root crops fed us during the winter. The Purple Sprouting
broccoli bloomed abundantly the next March.
In terms of quality, all the harvest was acceptable. The root
vegetables were far larger but only a little bit tougher and quite a
bit sweeter than usual. The potatoes yielded less than I'd been used
to and had thicker than usual skin, but also had a better flavor and
kept well through the winter.
The following year I grew two parallel gardens. One, my "insurance
garden," was thoroughly irrigated, guaranteeing we would have plenty
to eat. Another experimental garden of equal size was entirely
unirrigated. There I tested larger plots of species that I hoped
could grow through a rainless summer.
By July, growth on some species had slowed to a crawl and they
looked a little gnarly. Wondering if a hidden cause of what appeared
to be moisture stress might actually be nutrient deficiencies, I
tried spraying liquid fertilizer directly on these gnarly leaves, a
practice called foliar feeding. It helped greatly because, I
reasoned, most fertility is located in the topsoil, and when it gets
dry the plants draw on subsoil moisture, so surface nutrients,
though still present in the dry soil, become unobtainable. That
being so, I reasoned that some of these species might do even better
if they had just a little fertilized water. So I improvised a simple
drip system and metered out 4 or 5 gallons of liquid fertilizer to
some of the plants in late July and four gallons more in August. To
some species, extra fertilized water (what I call "fertigation")
hardly made any difference at all. But unirrigated winter squash
vines, which were small and scraggly and yielded about 15 pounds of
food, grew more lushly when given a few 5-gallon,
fertilizer-fortified assists and yielded 50 pounds. Thirty-five
pounds of squash for 25 extra gallons of water and a bit of extra
nutrition is a pretty good exchange in my book.
The next year I integrated all this new information into just one
garden. Water-loving species like lettuce and celery were grown
through the summer on a large, thoroughly irrigated raised bed. The
rest of the garden was given no irrigation at all or minimally
metered-out fertigations. Some unirrigated crops were foliar fed
weekly.
Everything worked in 1991! And I found still other species that I
could grow surprisingly well on surprisingly small amounts of
water[--]or none at all. So, the next year, 1992, I set up a
sprinkler system to water the intensive raised bed and used the
overspray to support species that grew better with some moisture
supplementation; I continued using my improvised drip system to help
still others, while keeping a large section of the garden entirely
unwatered. And at the end of that summer I wrote this book.
What follows is not mere theory, not something I read about or saw
others do. These techniques are tested and workable. The
next-to-last chapter of this book contains a complete plan of my
1992 garden with explanations and discussion of the reasoning behind
it.
In _Water-Wise Vegetables _I assume that my readers already are
growing food (probably on raised beds), already know how to adjust
their gardening to this region's climate, and know how to garden
with irrigation. If you don't have this background I suggest you
read my other garden book, _Growing Vegetables West of the
Cascades,_ (Sasquatch Books, 1989).
Steve Solomon
Chapter 1
Predictably Rainless Summers
In the eastern United States, summertime rainfall can support
gardens without irrigation but is just irregular enough to be
worrisome. West of the Cascades we go into the summer growing season
certain we must water regularly.
My own many-times-revised book _Growing Vegetables West of the
Cascades_ correctly emphasized that moisture-stressed vegetables
suffer greatly. Because I had not yet noticed how plant spacing
affects soil moisture loss, in that book I stated a half-truth as
law: Soil moisture loss averages 1-1/2 inches per week during
summer.
This figure is generally true for raised-bed gardens west of the
Cascades, so I recommended adding 1 1/2 inches of water each week
and even more during really hot weather.
Summertime Rainfall West of the Cascades (in inches)*
Location April May June July Aug. Sept. Oct.
Eureka, CA 3.0 2.1 0.7 0.1 0.3 0.7 3.2
Medford, OR 1.0 1.4 0.98 0.3 0.3 0.6 2.1
Eugene, OR 2.3 2.1 1.3 0.3 0.6 1.3 4.0
Portland, OR 2.2 2.1 1.6 0.5 0.8 1.6 3.6
Astoria, OR 4.6 2.7 2.5 1.0 1.5 2.8 6.8
Olympia, WA 3.1 1.9 1.6 0.7 1.2 2.1 5.3
Seattle, WA 2.4 1.7 1.6 0.8 1.0 2.1 4.0
Bellingham, WA 2.3 1.8 1.9 1.0 1.1 2.0 3.7
Vancouver, BC 3.3 2.8 2.5 1.2 1.7 3.6 5.8
Victoria, BC 1.2 1.0 0.9 0.4 0.6 1.5 2.8
*Source: Van der Leeden et al., _The Water Encyclopedia,_ 2nd
ed., (Chelsea, Mich.:Lewis Publishers, 1990).
Defined scientifically, drought is not lack of rain. It is a dry
soil condition in which plant growth slows or stops and plant
survival may be threatened. The earth loses water when wind blows,
when sun shines, when air temperature is high, and when humidity is
low. Of all these factors, air temperature most affects soil
moisture loss.
Daily Maximum Temperature (F)*
July/August Average
Eureka, CA 61
Medford, OR 89
Eugene, OR 82
Astoria, OR 68
Olympia, WA 78
Seattle, WA 75
Bellingham, WA 74
Vancouver, BC 73
Victoria, BC 68
*Source: The Water Encyclopedia.
The kind of vegetation growing on a particular plot and its density
have even more to do with soil moisture loss than temperature or
humidity or wind speed. And, surprising as it might seem, bare soil
may not lose much moisture at all. I now know it is next to
impossible to anticipate moisture loss from soil without first
specifying the vegetation there. Evaporation from a large body of
water, however, is mainly determined by weather, so reservoir
evaporation measurements serve as a rough gauge of anticipated soil
moisture loss.
Evaporation from Reservoirs (inches per month)*
Location April May June July Aug. Sept. Oct
Seattle, WA 2.1 2.7 3.4 3.9 3.4 2.6 1.6
Baker, OR 2.5 3.4 4.4 6.9 7.3 4.9 2.9
Sacramento, CA 3.6 5.0 7.1 8.9 8.6 7.1 4.8
*Source: _The Water Encyclopedia_
From May through September during a normal year, a reservoir near
Seattle loses about 16 inches of water by evaporation. The next
chart shows how much water farmers expect to use to support
conventional agriculture in various parts of the West. Comparing
this data for Seattle with the estimates based on reservoir
evaporation shows pretty good agreement. I include data for Umatilla
and Yakima to show that much larger quantities of irrigation water
are needed in really hot, arid places like Baker or Sacramento.
Estimated Irrigation Requirements:
During Entire Growing Season (in inches)*
Location Duration Amount
Umatilla/Yakama Valley April-October 30
Willamette Valley May-September 16
Puget Sound May-September 14
Upper Rogue/Upper Umpqua Valley March-September 18
Lower Rogue/Lower Coquille Valley May-September 11
NW California April-October 17
*Source: _The Water Encyclopedia_
In our region, gardens lose far more water than they get from
rainfall during the summer growing season. At first glance, it seems
impossible to garden without irrigation west of the Cascades. But
there is water already present in the soil when the gardening season
begins. By creatively using and conserving this moisture, some
maritime Northwest gardeners can go through an entire summer without
irrigating very much, and with some crops, irrigating not at all.
Chapter 2
Water-Wise Gardening Science
Plants Are Water
Like all other carbon-based life forms on earth, plants conduct
their chemical processes in a water solution. Every substance that
plants transport is dissolved in water. When insoluble starches and
oils are required for plant energy, enzymes change them back into
water-soluble sugars for movement to other locations. Even cellulose
and lignin, insoluble structural materials that plants cannot
convert back into soluble materials, are made from molecules that
once were in solution.
Water is so essential that when a plant can no longer absorb as much
water as it is losing, it wilts in self-defense. The drooping leaves
transpire (evaporate) less moisture because the sun glances off
them. Some weeds can wilt temporarily and resume vigorous growth as
soon as their water balance is restored. But most vegetable species
aren't as tough-moisture stressed vegetables may survive, but once
stressed, the quality of their yield usually drops markedly.
Yet in deep, open soil west of the Cascades, most vegetable species
may be grown quite successfully with very little or no supplementary
irrigation and without mulching, because they're capable of being
supplied entirely by water already stored in the soil.
Soil's Water-Holding Capacity
Soil is capable of holding on to quite a bit of water, mostly by
adhesion. For example, I'm sure that at one time or another you have
picked up a wet stone from a river or by the sea. A thin film of
water clings to its surface. This is adhesion. The more surface area
there is, the greater the amount of moisture that can be held by
adhesion. If we crushed that stone into dust, we would greatly
increase the amount of water that could adhere to the original
material. Clay particles, it should be noted, are so small that
clay's ability to hold water is not as great as its mathematically
computed surface area would indicate.
Surface Area of One Gram of Soil Particles
Particle type Diameter of particles in mm Number of particles per gm
Surface area in sq. cm.
Very coarse sand 2.00-1.00 90 11
Coarse sand 1.00-0.50 720 23
Medium sand 0.50-0.25 5,700 45
Fine sand 0.25-0.10 46,000 91
Very fine sand 0.10-0.05 772,000 227
Silt 0.05-0.002 5,776,000 454
Clay Below 0.002 90,260,853,000 8,000,000
Source: Foth, Henry D., _Fundamentals of Soil Science,_ 8th ed.
(New York: John Wylie & Sons, 1990).
This direct relationship between particle size, surface area, and
water-holding capacity is so essential to understanding plant growth
that the surface areas presented by various sizes of soil particles
have been calculated. Soils are not composed of a single size of
particle. If the mix is primarily sand, we call it a sandy soil. If
the mix is primarily clay, we call it a clay soil. If the soil is a
relatively equal mix of all three, containing no more than 35
percent clay, we call it a loam.
Available Moisture (inches of water per foot of soil)
Soil Texture Average Amount
Very coarse sand 0.5
Coarse sand 0.7
Sandy 1.0
Sandy loam 1.4
Loam 2.0
Clay loam 2.3
Silty clay 2.5
Clay 2.7
Source: _Fundamentals of Soil Science_.
Adhering water films can vary greatly in thickness. But if the water
molecules adhering to a soil particle become too thick, the force of
adhesion becomes too weak to resist the force of gravity, and some
water flows deeper into the soil. When water films are relatively
thick the soil feels wet and plant roots can easily absorb moisture.
"Field capacity" is the term describing soil particles holding all
the water they can against the force of gravity.
At the other extreme, the thinner the water films become, the more
tightly they adhere and the drier the earth feels. At some degree of
desiccation, roots are no longer forceful enough to draw on soil
moisture as fast as the plants are transpiring. This condition is
called the "wilting point." The term "available moisture" refers to
the difference between field capacity and the amount of moisture
left after the plants have died.
Clayey soil can provide plants with three times as much available
water as sand, six times as much as a very coarse sandy soil. It
might seem logical to conclude that a clayey garden would be the
most drought resistant. But there's more to it. For some crops, deep
sandy loams can provide just about as much usable moisture as clays.
Sandy soils usually allow more extensive root development, so a
plant with a naturally aggressive and deep root system may be able
to occupy a much larger volume of sandy loam, ultimately coming up
with more moisture than it could obtain from a heavy, airless clay.
And sandy loams often have a clayey, moisture-rich subsoil.
_Because of this interplay of factors, how much available water your
own unique garden soil is actually capable of providing and how much
you will have to supplement it with irrigation can only be
discovered by trial._
How Soil Loses Water
Suppose we tilled a plot about April 1 and then measured soil
moisture loss until October. Because plants growing around the edge
might extend roots into our test plot and extract moisture, we'll
make our tilled area 50 feet by 50 feet and make all our
measurements in the center. And let's locate this imaginary plot in
full sun on flat, uniform soil. And let's plant absolutely nothing
in this bare earth. And all season let's rigorously hoe out every
weed while it is still very tiny.
Let's also suppose it's been a typical maritime Northwest rainy
winter, so on April 1 the soil is at field capacity, holding all the
moisture it can. From early April until well into September the hot
sun will beat down on this bare plot. Our summer rains generally
come in insignificant installments and do not penetrate deeply; all
of the rain quickly evaporates from the surface few inches without
recharging deeper layers. Most readers would reason that a soil
moisture measurement taken 6 inches down on September 1, should show
very little water left. One foot down seems like it should be just
as dry, and in fact, most gardeners would expect that there would be
very little water found in the soil until we got down quite a few
feet if there were several feet of soil.
But that is not what happens! The hot sun does dry out the surface
inches, but if we dig down 6 inches or so there will be almost as
much water present in September as there was in April. Bare earth
does not lose much water at all. _Once a thin surface layer is
completely desiccated, be it loose or compacted, virtually no
further loss of moisture can occur._
The only soils that continue to dry out when bare are certain kinds
of very heavy clays that form deep cracks. These ever-deepening
openings allow atmospheric air to freely evaporate additional
moisture. But if the cracks are filled with dust by surface
cultivation, even this soil type ceases to lose water.
Soil functions as our bank account, holding available water in
storage. In our climate soil is inevitably charged to capacity by
winter rains, and then all summer growing plants make heavy
withdrawals. But hot sun and wind working directly on soil don't
remove much water; that is caused by hot sun and wind working on
plant leaves, making them transpire moisture drawn from the earth
through their root systems. Plants desiccate soil to the ultimate
depth and lateral extent of their rooting ability, and then some.
The size of vegetable root systems is greater than most gardeners
would think. The amount of moisture potentially available to sustain
vegetable growth is also greater than most gardeners think.
Rain and irrigation are not the only ways to replace soil moisture.
If the soil body is deep, water will gradually come up from below
the root zone by capillarity. Capillarity works by the very same
force of adhesion that makes moisture stick to a soil particle. A
column of water in a vertical tube (like a thin straw) adheres to
the tube's inner surfaces. This adhesion tends to lift the edges of
the column of water. As the tube's diameter becomes smaller the
amount of lift becomes greater. Soil particles form interconnected
pores that allow an inefficient capillary flow, recharging dry soil
above. However, the drier soil becomes, the less effective capillary
flow becomes. _That is why a thoroughly desiccated surface layer
only a few inches thick acts as a powerful mulch._
Industrial farming and modern gardening tend to discount the
replacement of surface moisture by capillarity, considering this
flow an insignificant factor compared with the moisture needs of
crops. But conventional agriculture focuses on maximized yields
through high plant densities. Capillarity is too slow to support
dense crop stands where numerous root systems are competing, but
when a single plant can, without any competition, occupy a large
enough area, moisture replacement by capillarity becomes
significant.
How Plants Obtain Water
Most gardeners know that plants acquire water and minerals through
their root systems, and leave it at that. But the process is not
quite that simple. The actively growing, tender root tips and almost
microscopic root hairs close to the tip absorb most of the plant's
moisture as they occupy new territory. As the root continues to
extend, parts behind the tip cease to be effective because, as soil
particles in direct contact with these tips and hairs dry out, the
older roots thicken and develop a bark, while most of the absorbent
hairs slough off. This rotation from being actively foraging tissue
to becoming more passive conductive and supportive tissue is
probably a survival adaptation, because the slow capillary movement
of soil moisture fails to replace what the plant used as fast as the
plant might like. The plant is far better off to aggressively seek
new water in unoccupied soil than to wait for the soil its roots
already occupy to be recharged.
A simple bit of old research magnificently illustrated the
significance of this. A scientist named Dittmer observed in 1937
that a single potted ryegrass plant allocated only 1 cubic foot of
soil to grow in made about 3 miles of new roots and root hairs every
day. (Ryegrasses are known to make more roots than most plants.) I
calculate that a cubic foot of silty soil offers about 30,000 square
feet of surface area to plant roots. If 3 miles of microscopic root
tips and hairs (roughly 16,000 lineal feet) draws water only from a
few millimeters of surrounding soil, then that single rye plant
should be able to continue ramifying into a cubic foot of silty soil
and find enough water for quite a few days before wilting. These
arithmetical estimates agree with my observations in the garden, and
with my experiences raising transplants in pots.
Lowered Plant Density: The Key to Water-Wise Gardening
I always think my latest try at writing a near-perfect garden book
is quite a bit better than the last. _Growing Vegetables West of the
Cascades_, recommended somewhat wider spacings on raised beds than I
did in 1980 because I'd repeatedly noticed that once a leaf canopy
forms, plant growth slows markedly. Adding a little more fertilizer
helps after plants "bump," but still the rate of growth never equals
that of younger plants. For years I assumed crowded plants stopped
producing as much because competition developed for light. But now I
see that unseen competition for root room also slows them down. Even
if moisture is regularly recharged by irrigation, and although
nutrients are replaced, once a bit of earth has been occupied by the
roots of one plant it is not so readily available to the roots of
another. So allocating more elbow room allows vegetables to get
larger and yield longer and allows the gardener to reduce the
frequency of irrigations.
Though hot, baking sun and wind can desiccate the few inches of
surface soil, withdrawals of moisture from greater depths are made
by growing plants transpiring moisture through their leaf surfaces.
The amount of water a growing crop will transpire is determined
first by the nature of the species itself, then by the amount of
leaf exposed to sun, air temperature, humidity, and wind. In these
respects, the crop is like an automobile radiator. With cars, the
more metal surfaces, the colder the ambient air, and the higher the
wind speed, the better the radiator can cool; in the garden, the
more leaf surfaces, the faster, warmer, and drier the wind, and the
brighter the sunlight, the more water is lost through transpiration.
Dealing with a Surprise Water Shortage
Suppose you are growing a conventional, irrigated garden and
something unanticipated interrupts your ability to water. Perhaps
you are homesteading and your well begins to dry up. Perhaps you're
a backyard gardener and the municipality temporarily restricts
usage. What to do?
First, if at all possible before the restrictions take effect, water
very heavily and long to ensure there is maximum subsoil moisture.
Then eliminate all newly started interplantings and ruthlessly hoe
out at least 75 percent of the remaining immature plants and about
half of those about two weeks away from harvest.
For example, suppose you've got a a 4-foot-wide intensive bed
holding seven rows of broccoli on 12 inch centers, or about 21
plants. Remove at least every other row and every other plant in the
three or four remaining rows. Try to bring plant density down to
those described in Chapter 5, "How to Grow It: A-Z"
Then shallowly hoe the soil every day or two to encourage the
surface inches to dry out and form a dust mulch. You water-wise
person--you're already dry gardening--now start fertigating.
How long available soil water will sustain a crop is determined by
how many plants are drawing on the reserve, how extensively their
root systems develop, and how many leaves are transpiring the
moisture. If there are no plants, most of the water will stay unused
in the barren soil through the entire growing season. If a crop
canopy is established midway through the growing season, the rate of
water loss will approximate that listed in the table in Chapter 1
"Estimated Irrigation Requirement." If by very close planting the
crop canopy is established as early as possible and maintained by
successive interplantings, as is recommended by most advocates of
raised-bed gardening, water losses will greatly exceed this rate.
Many vegetable species become mildly stressed when soil moisture has
dropped about half the way from capacity to the wilting point. On
very closely planted beds a crop can get in serious trouble without
irrigation in a matter of days. But if that same crop were planted
less densely, it might grow a few weeks without irrigation. And if
that crop were planted even farther apart so that no crop canopy
ever developed and a considerable amount of bare, dry earth were
showing, this apparent waste of growing space would result in an
even slower rate of soil moisture depletion. On deep, open soil the
crop might yield a respectable amount without needing any irrigation
at all.
West of the Cascades we expect a rainless summer; the surprise comes
that rare rainy year when the soil stays moist and we gather
bucketfuls of chanterelle mushrooms in early October. Though the
majority of maritime Northwest gardeners do not enjoy deep, open,
moisture-retentive soils, all except those with the shallowest soil
can increase their use of the free moisture nature provides and
lengthen the time between irrigations. The next chapter discusses
making the most of whatever soil depth you have. Most of our
region's gardens can yield abundantly without any rain at all if
only we reduce competition for available soil moisture, judiciously
fertigate some vegetable species, and practice a few other
water-wise tricks.
_Would lowering plant density as much as this book suggests equally
lower the yield of the plot? Surprisingly, the amount harvested does
not drop proportionately. In most cases having a plant density
one-eighth of that recommended by intensive gardening advocates will
result in a yield about half as great as on closely planted raised
beds._
Internet Readers: In the print copy of this book are color pictures
of my own "irrigationless" garden. Looking at them about here in the
book would add reality to these ideas.
Chapter 3
Helping Plants to Need Less Irrigation
Dry though the maritime Northwest summer is, we enter the growing
season with our full depth of soil at field capacity. Except on
clayey soils in extraordinarily frosty, high-elevation locations, we
usually can till and plant before the soil has had a chance to lose
much moisture.
There are a number of things we can do to make soil moisture more
available to our summer vegetables. The most obvious step is
thorough weeding. Next, we can keep the surface fluffed up with a
rotary tiller or hoe during April and May, to break its capillary
connection with deeper soil and accelerate the formation of a dry
dust mulch. Usually, weeding forces us to do this anyway. Also, if
it should rain during summer, we can hoe or rotary till a day or two
later and again help a new dust mulch to develop.
Building Bigger Root Systems
Without irrigation, most of the plant's water supply is obtained by
expansion into new earth that hasn't been desiccated by other
competing roots. Eliminating any obstacles to rapid growth of root
systems is the key to success. So, keep in mind a few facts about
how roots grow and prosper.
The air supply in soil limits or allows root growth. Unlike the
leaves, roots do not perform photosynthesis, breaking down carbon
dioxide gas into atmospheric oxygen and carbon. Yet root cells must
breathe oxygen. This is obtained from the air held in spaces between
soil particles. Many other soil-dwelling life forms from bacteria to
moles compete for this same oxygen. Consequently, soil oxygen levels
are lower than in the atmosphere. A slow exchange of gases does
occur between soil air and free atmosphere, but deeper in the soil
there will inevitably be less oxygen. Different plant species have
varying degrees of root tolerance for lack of oxygen, but they all
stop growing at some depth. Moisture reserves below the roots'
maximum depth beecome relatively inaccessible.
Soil compaction reduces the overall supply and exchange of soil air.
Compacted soil also acts as a mechanical barrier to root system
expansion. When gardening with unlimited irrigation or where rain
falls frequently, it is quite possible to have satisfactory growth
when only the surface 6 or 7 inches of soil facilitates root
development. When gardening with limited water, China's the limit,
because if soil conditions permit, many vegetable species are
capable of reaching 4, 5, and 8 eight feet down to find moisture and
nutrition.
Evaluating Potential Rooting Ability
One of the most instructive things a water-wise gardener can do is
to rent or borrow a hand-operated fence post auger and bore a
3-foot-deep hole. It can be even more educational to buy a short
section of ordinary water pipe to extend the auger's reach another 2
or 3 feet down. In soil free of stones, using an auger is more
instructive than using a conventional posthole digger or shoveling
out a small pit, because where soil is loose, the hole deepens
rapidly. Where any layer is even slightly compacted, one turns and
turns the bit without much effect. Augers also lift the materials
more or less as they are stratified. If your soil is somewhat stony
(like much upland soil north of Centralia left by the Vashon
Glacier), the more usual fence-post digger or common shovel works
better.
If you find more than 4 feet of soil, the site holds a dry-gardening
potential that increases with the additional depth. Some soils along
the floodplains of rivers or in broad valleys like the Willamette or
Skagit can be over 20 feet deep, and hold far more water than the
deepest roots could draw or capillary flow could raise during an
entire growing season. Gently sloping land can often carry 5 to 7
feet of open, usable soil. However, soils on steep hillsides become
increasingly thin and fragile with increasing slope.
Whether an urban, suburban, or rural gardener, you should make no
assumptions about the depth and openness of the soil at your
disposal. Dig a test hole. If you find less than 2 unfortunate feet
of open earth before hitting an impermeable obstacle such as rock or
gravel, not much water storage can occur and the only use this book
will hold for you is to guide your move to a more likely gardening
location or encourage the house hunter to seek further. Of course,
you can still garden quite successfully on thin soil in the
conventional, irrigated manner. _Growing Vegetables West of the
Cascades_ will be an excellent guide for this type of situation.
Eliminating Plowpan
Deep though the soil may be, any restriction of root expansion
greatly limits the ability of plants to aggressively find water. A
compacted subsoil or even a thin compressed layer such as plowpan
may function as such a barrier. Though moisture will still rise
slowly by capillarity and recharge soil above plowpan, plants obtain
much more water by rooting into unoccupied, damp soil. Soils close
to rivers or on floodplains may appear loose and infinitely deep but
may hide subsoil streaks of droughty gravel that effectively stops
root growth. Some of these conditions are correctable and some are
not.
Plowpan is very commonly encountered by homesteaders on farm soils
and may be found in suburbia too, but fortunately it is the easiest
obstacle to remedy. Traditionally, American croplands have been
tilled with the moldboard plow. As this implement first cuts and
then flips a 6-or 7-inch-deep slice of soil over, the sole--the part
supporting the plow's weight--presses heavily on the earth about 7
inches below the surface. With each subsequent plowing the plow sole
rides at the same 7-inch depth and an even more compacted layer
develops. Once formed plowpan prevents the crop from rooting into
the subsoil. Since winter rains leach nutrients from the topsoil and
deposit them in the subsoil, plowpan prevents access to these
nutrients and effectively impoverishes the field. So wise farmers
periodically use a subsoil plow to fracture the pan.
Plowpan can seem as firm as a rammed-earth house; once established,
it can last a long, long time. My own garden land is part of what
was once an old wheat farm, one of the first homesteads of the
Oregon Territory. From about 1860 through the 1930s, the field
produced small grains. After wheat became unprofitable, probably
because of changing market conditions and soil exhaustion, the field
became an unplowed pasture. Then in the 1970s it grew daffodil
bulbs, occasioning more plowing. All through the '80s my soil again
rested under grass. In 1987, when I began using the land, there was
still a 2-inch-thick, very hard layer starting about 7 inches down.
Below 9 inches the open earth is soft as butter as far as I've ever
dug.
On a garden-sized plot, plowpan or compacted subsoil is easily
opened with a spading fork or a very sharp common shovel. After
normal rotary tilling, either tool can fairly easily be wiggled 12
inches into the earth and small bites of plowpan loosened. Once this
laborious chore is accomplished the first time, deep tillage will be
far easier. In fact, it becomes so easy that I've been looking for a
custom-made fork with longer tines.
Curing Clayey Soils
In humid climates like ours, sandy soils may seem very open and
friable on the surface but frequently hold some unpleasant subsoil
surprises. Over geologic time spans, mineral grains are slowly
destroyed by weak soil acids and clay is formed from the breakdown
products. Then heavy winter rainfall transports these minuscule clay
particles deeper into the earth, where they concentrate. It is not
unusual to find a sandy topsoil underlaid with a dense, cement-like,
clayey sand subsoil extending down several feet. If very impervious,
a thick, dense deposition like this may be called hardpan.
The spading fork cannot cure this condition as simply as it can
eliminate thin plowpan. Here is one situation where, if I had a
neighbor with a large tractor and subsoil plow, I'd hire him to
fracture my land 3 or 4 feet deep. Painstakingly double or even
triple digging will also loosen this layer. Another possible
strategy for a smaller garden would be to rent a gasoline-powered
posthole auger, spread manure or compost an inch or two thick, and
then bore numerous, almost adjoining holes 4 feet deep all over the
garden.
Clayey subsoil can supply surprisingly larger amounts of moisture
than the granular sandy surface might imply, but only if the earth
is opened deeply and becomes more accessible to root growth.
Fortunately, once root development increases at greater depths, the
organic matter content and accessibility of this clayey layer can be
maintained through intelligent green manuring, postponing for years
the need to subsoil again. Green manuring is discussed in detail
shortly.
Other sites may have gooey, very fine clay topsoils, almost
inevitably with gooey, very fine clay subsoils as well. Though
incorporation of extraordinarily large quantities of organic matter
can turn the top few inches into something that behaves a little
like loam, it is quite impractical to work in humus to a depth of 4
or 5 feet. Root development will still be limited to the surface
layer. Very fine clays don't make likely dry gardens.
Not all clay soils are "fine clay soils," totally compacted and
airless. For example, on the gentler slopes of the geologic old
Cascades, those 50-million-year-old black basalts that form the
Cascades foothills and appear in other places throughout the
maritime Northwest, a deep, friable, red clay soil called (in
Oregon) Jori often forms. Jori clays can be 6 to 8 feet deep and are
sufficiently porous and well drained to have been used for highly
productive orchard crops. Water-wise gardeners can do wonders with
Joris and other similar soils, though clays never grow the best root
crops.
Spotting a Likely Site
Observing the condition of wild plants can reveal a good site to
garden without much irrigation. Where Himalaya or Evergreen
blackberries grow 2 feet tall and produce small, dull-tasting fruit,
there is not much available soil moisture. Where they grow 6 feet
tall and the berries are sweet and good sized, there is deep, open
soil. When the berry vines are 8 or more feet tall and the fruits
are especially huge, usually there is both deep, loose soil and a
higher than usual amount of fertility.
Other native vegetation can also reveal a lot about soil moisture
reserves. For years I wondered at the short leaders and sad
appearance of Douglas fir in the vicinity of Yelm, Washington. Were
they due to extreme soil infertility? Then I learned that conifer
trees respond more to summertime soil moisture than to fertility. I
obtained a soil survey of Thurston County and discovered that much
of that area was very sandy with gravelly subsoil. Eureka!
The Soil Conservation Service (SCS), a U.S. Government agency, has
probably put a soil auger into your very land or a plot close by.
Its tests have been correlated and mapped; the soils underlying the
maritime Northwest have been named and categorized by texture,
depth, and ability to provide available moisture. The maps are
precise and detailed enough to approximately locate a city or
suburban lot. In 1987, when I was in the market for a new homestead,
I first went to my county SCS office, mapped out locations where the
soil was suitable, and then went hunting. Most counties have their
own office.
Using Humus to Increase Soil Moisture
Maintaining topsoil humus content in the 4 to 5 percent range is
vital to plant health, vital to growing more nutritious food, and
essential to bringing the soil into that state of easy workability
and cooperation known as good tilth. Humus is a spongy substance
capable of holding several times more available moisture than clay.
There are also new synthetic, long-lasting soil amendments that hold
and release even more moisture than humus. Garden books frequently
recommend tilling in extraordinarily large amounts of organic matter
to increase a soil's water-holding capacity in the top few inches.
Humus can improve many aspects of soil but will not reduce a
garden's overall need for irrigation, because it is simply not
practical to maintain sufficient humus deeply enough. Rotary tilling
only blends amendments into the top 6 or 7 inches of soil. Rigorous
double digging by actually trenching out 12 inches and then spading
up the next foot theoretically allows one to mix in significant
amounts of organic matter to nearly 24 inches. But plants can use
water from far deeper than that. Let's realistically consider how
much soil moisture reserves might be increased by double digging and
incorporating large quantities of organic matter.
A healthy topsoil organic matter level in our climate is about 4
percent. This rapidly declines to less than 0.5 percent in the
subsoil. Suppose inches-thick layers of compost were spread and, by
double digging, the organic matter content of a very sandy soil were
amended to 10 percent down to 2 feet. If that soil contained little
clay, its water-holding ability in the top 2 feet could be doubled.
Referring to the chart "Available Moisture" in Chapter 2, we see
that sandy soil can release up to 1 inch of water per foot. By dint
of massive amendment we might add 1 inch of available moisture per
foot of soil to the reserve. That's 2 extra inches of water, enough
to increase the time an ordinary garden can last between heavy
irrigations by a week or 10 days.
If the soil in question were a silty clay, it would naturally make 2
1/2 inches available per foot. A massive humus amendment would
increase that to 3 1/2 inches in the top foot or two, relatively not
as much benefit as in sandy soil. And I seriously doubt that many
gardeners would be willing to thoroughly double dig to an honest 24
inches.
Trying to maintain organic matter levels above 10 percent is an
almost self-defeating process. The higher the humus level gets, the
more rapidly organic matter tends to decay. Finding or making enough
well-finished compost to cover the garden several inches deep (what
it takes to lift humus levels to 10 percent) is enough of a job.
Double digging just as much more into the second foot is even more
effort. But having to repeat that chore every year or two becomes
downright discouraging. No, either your soil naturally holds enough
moisture to permit dry gardening, or it doesn't.
Keeping the Subsoil Open with Green Manuring
When roots decay, fresh organic matter and large, long-lasting
passageways can be left deep in the soil, allowing easier air
movement and facilitating entry of other roots. But no cover crop
that I am aware of will effectively penetrate firm plowpan or other
resistant physical obstacles. Such a barrier forces all plants to
root almost exclusively in the topsoil. However, once the subsoil
has been mechanically fractured the first time, and if recompaction
is avoided by shunning heavy tractors and other machinery, green
manure crops can maintain the openness of the subsoil.
To accomplish this, correct green manure species selection is
essential. Lawn grasses tend to be shallow rooting, while most
regionally adapted pasture grasses can reach down about 3 feet at
best. However, orchard grass (called coltsfoot in English farming
books) will grow down 4 or more feet while leaving a massive amount
of decaying organic matter in the subsoil after the sod is tilled
in. Sweet clover, a biennial legume that sprouts one spring then
winters over to bloom the next summer, may go down 8 feet. Red
clover, a perennial species, may thickly invade the top 5 feet.
Other useful subsoil busters include densely sown Umbelliferae such
as carrots, parsley, and parsnip. The chicory family also makes very
large and penetrating taproots.
Though seed for wild chicory is hard to obtain, cheap varieties of
endive (a semicivilized relative) are easily available. And several
pounds of your own excellent parsley or parsnip seed can be easily
produced by letting about 10 row feet of overwintering roots form
seed. Orchard grass and red clover can be had quite inexpensively at
many farm supply stores. Sweet clover is not currently grown by our
region's farmers and so can only be found by mail from Johnny's
Selected Seeds (see Chapter 5 for their address). Poppy seed used
for cooking will often sprout. Sown densely in October, it forms a
thick carpet of frilly spring greens underlaid with countless
massive taproots that decompose very rapidly if the plants are
tilled in in April before flower stalks begin to appear. Beware if
using poppies as a green manure crop: be sure to till them in early
to avoid trouble with the DEA or other authorities.
For country gardeners, the best rotations include several years of
perennial grass-legume-herb mixtures to maintain the openness of the
subsoil followed by a few years of vegetables and then back (see
Newman Turner's book in more reading). I plan my own garden this
way. In October, after a few inches of rain has softened the earth,
I spread 50 pounds of agricultural lime per 1,000 square feet and
break the thick pasture sod covering next year's garden plot by
shallow rotary tilling. Early the next spring I broadcast a
concoction I call "complete organic fertilizer" (see _Growing
Vegetables West of the Cascades_ or the _Territorial Seed Company
Catalog_), till again after the soil dries down a bit, and then use
a spading fork to open the subsoil before making a seedbed. The
first time around, I had to break the century-old plowpan--forking
compacted earth a foot deep is a lot of work. In subsequent
rotations it is much much easier.
For a couple of years, vegetables will grow vigorously on this new
ground supported only with a complete organic fertilizer. But
vegetable gardening makes humus levels decline rapidly. So every few
years I start a new garden on another plot and replant the old
garden to green manures. I never remove vegetation during the long
rebuilding under green manures, but merely mow it once or twice a
year and allow the organic matter content of the soil to redevelop.
If there ever were a place where chemical fertilizers might be
appropriate around a garden, it would be to affordably enhance the
growth of biomass during green manuring.
Were I a serious city vegetable gardener, I'd consider growing
vegetables in the front yard for a few years and then switching to
the back yard. Having lots of space, as I do now, I keep three or
four garden plots available, one in vegetables and the others
restoring their organic matter content under grass.
Mulching
Gardening under a permanent thick mulch of crude organic matter is
recommended by Ruth Stout (see the listing for her book in More
Reading) and her disciples as a surefire way to drought-proof
gardens while eliminating virtually any need for tillage, weeding,
and fertilizing. I have attempted the method in both Southern
California and western Oregon--with disastrous results in both
locations. What follows in this section is addressed to gardeners
who have already read glowing reports about mulching.
Permanent mulching with vegetation actually does not reduce
summertime moisture loss any better than mulching with dry soil,
sometimes called "dust mulching." True, while the surface layer
stays moist, water will steadily be wicked up by capillarity and be
evaporated from the soil's surface. If frequent light sprinkling
keeps the surface perpetually moist, subsoil moisture loss can occur
all summer, so unmulched soil could eventually become desiccated
many feet deep. However, capillary movement only happens when soil
is damp. Once even a thin layer of soil has become quite dry it
almost completely prevents any further movement. West of the
Cascades, this happens all by itself in late spring. One hot, sunny
day follows another, and soon the earth's surface seems parched.
Unfortunately, by the time a dusty layer forms, quite a bit of soil
water may have risen from the depths and been lost. The gardener can
significantly reduce spring moisture loss by frequently hoeing weeds
until the top inch or two of earth is dry and powdery. This effort
will probably be necessary in any case, because weeds will germinate
prolifically until the surface layer is sufficiently desiccated. On
the off chance it should rain hard during summer, it is very wise to
again hoe a few times to rapidly restore the dust mulch. If hand
cultivation seems very hard work, I suggest you learn to sharpen
your hoe.
A mulch of dry hay, grass clippings, leaves, and the like will also
retard rapid surface evaporation. Gardeners think mulching prevents
moisture loss better than bare earth because under mulch the soil
stays damp right to the surface. However, dig down 4 to 6 inches
under a dust mulch and the earth is just as damp as under hay. And,
soil moisture studies have proved that overall moisture loss using
vegetation mulch slightly exceeds loss under a dust mulch.
West of the Cascades, the question of which method is superior is a
bit complex, with pros and cons on both sides. Without a long winter
freeze to set populations back, permanent thick mulch quickly breeds
so many slugs, earwhigs, and sowbugs that it cannot be maintained
for more than one year before vegetable gardening becomes very
difficult. Laying down a fairly thin mulch in June after the soil
has warmed up well, raking up what remains of the mulch early the
next spring, and composting it prevents destructive insect
population levels from developing while simultaneously reducing
surface compaction by winter rains and beneficially enhancing the
survival and multiplication of earthworms. But a thin mulch also
enhances the summer germination of weed seeds without being thick
enough to suppress their emergence. And any mulch, even a thin one,
makes hoeing virtually impossible, while hand weeding through mulch
is tedious.
Mulch has some unqualified pluses in hotter climates. Most of the
organic matter in soil and consequently most of the available
nitrogen is found in the surface few inches. Levels of other mineral
nutrients are usually two or three times as high in the topsoil as
well. However, if the surface few inches of soil becomes completely
desiccated, no root activity will occur there and the plants are
forced to feed deeper, in soil far less fertile. Keeping the topsoil
damp does greatly improve the growth of some shallow-feeding species
such as lettuce and radishes. But with our climate's cool nights,
most vegetables need the soil as warm as possible, and the cooling
effect of mulch can be as much a hindrance as a help. I've tried
mulching quite a few species while dry gardening and found little or
no improvement in plant growth with most of them. Probably, the
enhancement of nutrition compensates for the harm from lowering soil
temperature. Fertigation is better all around.
Windbreaks
Plants transpire more moisture when the sun shines, when
temperatures are high, and when the wind blows; it is just like
drying laundry. Windbreaks also help the garden grow in winter by
increasing temperature. Many other garden books discuss windbreaks,
and I conclude that I have a better use for the small amount of
words my publisher allows me than to repeat this data; Binda
Colebrook's [i]Winter Gardening in the Maritime Northwest[i]
(Sasquatch Books, 1989) is especially good on this topic.
Fertilizing, Fertigating and Foliar Spraying
In our heavily leached region almost no soil is naturally rich,
while fertilizers, manures, and potent composts mainly improve the
topsoil. But the water-wise gardener must get nutrition down deep,
where the soil stays damp through the summer.
If plants with enough remaining elbow room stop growing in summer
and begin to appear gnarly, it is just as likely due to lack of
nutrition as lack of water. Several things can be done to limit or
prevent midsummer stunting. First, before sowing or transplanting
large species like tomato, squash or big brassicas, dig out a small
pit about 12 inches deep and below that blend in a handful or two of
organic fertilizer. Then fill the hole back in. This double-digging
process places concentrated fertility mixed 18 to 24 inches below
the seeds or seedlings.
Foliar feeding is another water-wise technique that keeps plants
growing through the summer. Soluble nutrients sprayed on plant
leaves are rapidly taken into the vascular system. Unfortunately,
dilute nutrient solutions that won't burn leaves only provoke a
strong growth response for 3 to 5 days. Optimally, foliar nutrition
must be applied weekly or even more frequently. To efficiently spray
a garden larger than a few hundred square feet, I suggest buying an
industrial-grade, 3-gallon backpack sprayer with a side-handle pump.
Approximate cost as of this writing was $80. The store that sells it
(probably a farm supply store) will also support you with a complete
assortment of inexpensive nozzles that can vary the rate of emission
and the spray pattern. High-quality equipment like this outlasts
many, many cheaper and smaller sprayers designed for the consumer
market, and replacement parts are also available. Keep in mind that
consumer merchandise is designed to be consumed; stuff made for
farming is built to last.
Increasing Soil Fertility Saves Water
Does crop growth equal water use? Most people would say this
statement seems likely to be true.
Actually, faster-growing crops use much less soil moisture than
slower-growing ones. As early as 1882 it was determined that less
water is required to produce a pound of plant material when soil is
fertilized than when it is not fertilized. One experiment required
1,100 pounds of water to grow 1 pound of dry matter on infertile
soil, but only 575 pounds of water to produce a pound of dry matter
on rich land. Perhaps the single most important thing a water-wise
gardener can do is to increase the fertility of the soil, especially
the subsoil.
_Poor plant nutrition increases the water cost of every pound of dry
matter produced._
Using foliar fertilizers requires a little caution and forethought.
Spinach, beet, and chard leaves seem particularly sensitive to
foliars (and even to organic insecticides) and may be damaged by
even half-strength applications. And the cabbage family coats its
leaf surfaces with a waxy, moisture-retentive sealant that makes
sprays bead up and run off rather than stick and be absorbed. Mixing
foliar feed solutions with a little spreader/sticker, Safer's Soap,
or, if bugs are also a problem, with a liquid organic insecticide
like Red Arrow (a pyrethrum-rotenone mix), eliminates surface
tension and allows the fertilizer to have an effect on brassicas.
Sadly, in terms of nutrient balance, the poorest foliar sprays are
organic. That's because it is nearly impossible to get significant
quantities of phosphorus or calcium into solution using any
combination of fish emulsion and seaweed or liquid kelp. The most
useful possible organic foliar is 1/2 to 1 tablespoon each of fish
emulsion and liquid seaweed concentrate per gallon of water.
Foliar spraying and fertigation are two occasions when I am
comfortable supplementing my organic fertilizers with water-soluble
chemical fertilizers. The best and most expensive brand is
Rapid-Gro. Less costly concoctions such as Peters 20-20-20 or the
other "Grows," don't provide as complete trace mineral support or
use as many sources of nutrition. One thing fertilizer makers find
expensive to accomplish is concocting a mixture of soluble nutrients
that also contains calcium, a vital plant food. If you dissolve
calcium nitrate into a solution containing other soluble plant
nutrients, many of them will precipitate out because few calcium
compounds are soluble. Even Rapid-Gro doesn't attempt to supply
calcium. Recently I've discovered better-quality hydroponic nutrient
solutions that do use chemicals that provide soluble calcium. These
also make excellent foliar sprays. Brands of hydroponic nutrient
solutions seem to appear and vanish rapidly. I've had great luck
with Dyna-Gro 7-9-5. All these chemicals are mixed at about 1
tablespoon per gallon.
Vegetables That:
Like foliars
Asparagus Carrots Melons Squash
Beans Cauliflower Peas Tomatoes
Broccoli Brussels sprouts Cucumbers
Cabbage Eggplant Radishes
Kale Rutabagas Potatoes
Don't like foliars
Beets Leeks Onions Spinach
Chard Lettuce Peppers
Like fertigation
Brussels sprouts Kale Savoy cabbage
Cucumbers Melons Squash
Eggplant Peppers Tomatoes
Fertigation every two to four weeks is the best technique for
maximizing yield while minimizing water use. I usually make my first
fertigation late in June and continue periodically through early
September. I use six or seven plastic 5-gallon "drip system"
buckets, (see below) set one by each plant, and fill them all with a
hose each time I work in the garden. Doing 12 or 14 plants each time
I'm in the garden, it takes no special effort to rotate through them
all more or less every three weeks.
To make a drip bucket, drill a 3/16-inch hole through the side of a
4-to-6-gallon plastic bucket about 1/4-inch up from the bottom, or
in the bottom at the edge. The empty bucket is placed so that the
fertilized water drains out close to the stem of a plant. It is then
filled with liquid fertilizer solution. It takes 5 to 10 minutes for
5 gallons to pass through a small opening, and because of the slow
flow rate, water penetrates deeply into the subsoil without wetting
much of the surface. Each fertigation makes the plant grow very
rapidly for two to three weeks, more I suspect as a result of
improved nutrition than from added moisture. Exactly how and when to
fertigate each species is explained in Chapter 5.
Organic gardeners may fertigate with combinations of fish emulsion
and seaweed at the same dilution used for foliar spraying, or with
compost/manure tea. Determining the correct strength to make compost
tea is a matter of trial and error. I usually rely on weak Rapid-Gro
mixed at half the recommended dilution. The strength of the
fertilizer you need depends on how much and deeply you placed
nutrition in the subsoil.
Chapter 4
Water-Wise Gardening Year-Round
Early Spring: The Easiest Unwatered Garden
West of the Cascades, most crops started in February and March
require no special handling when irrigation is scarce. These include
peas, early lettuce, radishes, kohlrabi, early broccoli, and so
forth. However, some of these vegetables are harvested as late as
June, so to reduce their need for irrigation, space them wider than
usual. Spring vegetables also will exhaust most of the moisture from
the soil before maturing, making succession planting impossible
without first irrigating heavily. Early spring plantings are best
allocated one of two places in the garden plan: either in that part
of the garden that will be fully irrigated all summer or in a part
of a big garden that can affordably remain bare during the summer
and be used in October for receiving transplants of overwintering
crops. The garden plan and discussion in Chapter 6 illustrate these
ideas in detail.
Later in Spring: Sprouting Seeds Without Watering
For the first years that I experimented with dry gardening I went
overboard and attempted to grow food as though I had no running
water at all. The greatest difficulty caused by this self-imposed
handicap was sowing small-seeded species after the season warmed up.
Sprouting what we in the seed business call "big seed"--corn, beans,
peas, squash, cucumber, and melon--is relatively easy without
irrigation because these crops are planted deeply, where soil
moisture still resides long after the surface has dried out. And
even if it is so late in the season that the surface has become very
dry, a wide, shallow ditch made with a shovel will expose moist soil
several inches down. A furrow can be cut in the bottom of that damp
"valley" and big seeds germinated with little or no watering.
Tillage breaks capillary connections until the fluffy soil
resettles. This interruption is useful for preventing moisture loss
in summer, but the same phenomenon makes the surface dry out in a
flash. In recently tilled earth, successfully sprouting small seeds
in warm weather is dicey without frequent watering.
With a bit of forethought, the water-wise gardener can easily
reestablish capillarity below sprouting seeds so that moisture held
deeper in the soil rises to replace that lost from surface layers,
reducing or eliminating the need for watering. The principle here
can be easily demonstrated. In fact, there probably isn't any
gardener who has not seen the phenomenon at work without realizing
it. Every gardener has tilled the soil, gone out the next morning,
and noticed that his or her compacted footprints were moist while
the rest of the earth was dry and fluffy. Foot pressure restored
capillarity, and during the night, fresh moisture replaced what had
evaporated.
This simple technique helps start everything except carrots and
parsnips (which must have completely loose soil to develop
correctly). All the gardener must do is intentionally compress the
soil below the seeds and then cover the seeds with a mulch of loose,
dry soil. Sprouting seeds then rest atop damp soil exactly they lie
on a damp blotter in a germination laboratory's covered petri dish.
This dampness will not disappear before the sprouting seedling has
propelled a root several inches farther down and is putting a leaf
into the sunlight.
I've used several techniques to reestablish capillarity after
tilling. There's a wise old plastic push planter in my garage that
first compacts the tilled earth with its front wheel, cuts a furrow,
drops the seed, and then with its drag chain pulls loose soil over
the furrow. I've also pulled one wheel of a garden cart or pushed a
lightly loaded wheelbarrow down the row to press down a wheel track,
sprinkled seed on that compacted furrow, and then pulled loose soil
over it.
Handmade Footprints
Sometimes I sow large brassicas and cucurbits in clumps above a
fertilized, double-dug spot. First, in a space about 18 inches
square, I deeply dig in complete organic fertilizer. Then with my
fist I punch down a depression in the center of the fluffed-up
mound. Sometimes my fist goes in so easily that I have to replace a
little more soil and punch it down some more. The purpose is not to
make rammed earth or cement, but only to reestablish capillarity by
having firm soil under a shallow, fist-sized depression. Then a
pinch of seed is sprinkled atop this depression and covered with
fine earth. Even if several hot sunny days follow I get good
germination without watering. This same technique works excellently
on hills of squash, melon and cucumber as well, though these
large-seeded species must be planted quite a bit deeper.
Summer: How to Fluid Drill Seeds
Soaking seeds before sowing is another water-wise technique,
especially useful later in the season. At bedtime, place the seeds
in a half-pint mason jar, cover with a square of plastic window
screen held on with a strong rubber band, soak the seeds overnight,
and then drain them first thing in the morning. Gently rinse the
seeds with cool water two or three times daily until the root tips
begin to emerge. As soon as this sign appears, the seed must be
sown, because the newly emerging roots become increasingly subject
to breaking off as they develop and soon form tangled masses.
Presprouted seeds may be gently blended into some crumbly, moist
soil and this mixture gently sprinkled into a furrow and covered. If
the sprouts are particularly delicate or, as with carrots, you want
a very uniform stand, disperse the seeds in a starch gelatin and
imitate what commercial vegetable growers call fluid drilling.
Heat one pint of water to the boiling point. Dissolve in 2 to 3
tablespoons of ordinary cornstarch. Place the mixture in the
refrigerator to cool. Soon the liquid will become a soupy gel.
Gently mix this cool starch gel with the sprouting seeds, making
sure the seeds are uniformly blended. Pour the mixture into a
1-quart plastic zipper bag and, scissors in hand, go out to the
garden. After a furrow--with capillarity restored--has been
prepared, cut a small hole in one lower corner of the plastic bag.
The hole size should be under 1/4 inch in diameter. Walk quickly
down the row, dribbling a mixture of gel and seeds into the furrow.
Then cover. You may have to experiment a few times with cooled gel
minus seeds until you divine the proper hole size, walking speed and
amount of gel needed per length of furrow. Not only will presprouted
seeds come up days sooner, and not only will the root be penetrating
moist soil long before the shoot emerges, but the stand of seedlings
will be very uniformly spaced and easier to thin. After fluid
drilling a few times you'll realize that one needs quite a bit less
seed per length of row than you previously thought.
Establishing the Fall and Winter Garden
West of the Cascades, germinating fall and winter crops in the heat
of summer is always difficult. Even when the entire garden is well
watered, midsummer sowings require daily attention and frequent
sprinkling; however, once they have germinated, keeping little
seedlings growing in an irrigated garden usually requires no more
water than the rest of the garden gets. But once hot weather comes,
establishing small seeds in the dry garden seems next to impossible
without regular watering. Should a lucky, perfectly timed, and
unusually heavy summer rainfall sprout your seeds, they still would
not grow well because the next few inches of soil would at best be
only slightly moist.
A related problem many backyard gardeners have with establishing the
winter and overwintered garden is finding enough space for both the
summer and winter crops. The nursery bed solves both these problems.
Instead of trying to irrigate the entire area that will eventually
be occupied by a winter or overwintered crop at maturity, the
seedlings are first grown in irrigated nurseries for transplanting
in autumn after the rains come back. Were I desperately short of
water I'd locate my nursery where it got only morning sun and sow a
week or 10 days earlier to compensate for the slower growth.
Vegetables to Start in a Nursery Bed
Variety Sowing date Transplanting date
Fall/winter lettuce mid-August early October
Leeks early April July
Overwintered onions early-mid August December/January
Spring cabbage mid-late August November/December
Spring cauliflower mid-August October/November 1st
Winter scallions mid-July mid-October
Seedlings in pots and trays are hard to keep moist and require daily
tending. Fortunately, growing transplants in little pots is not
necessary because in autumn, when they'll be set out, humidity is
high, temperatures are cool, the sun is weak, and transpiration
losses are minimal, so seedling transplants will tolerate
considerable root loss. My nursery is sown in rows about 8 inches
apart across a raised bed and thinned gradually to prevent crowding,
because crowded seedlings are hard to dig out without damage. When
the prediction of a few days of cloudy weather encourages
transplanting, the seedlings are lifted with a large, sharp knife.
If the fall rains are late and/or the crowded seedlings are getting
leggy, a relatively small amount of irrigation will moisten the
planting areas. Another light watering at transplanting time will
almost certainly establish the seedlings quite successfully. And,
finding room for these crops ceases to be a problem because fall
transplants can be set out as a succession crop following hot
weather vegetables such as squash, melons, cucumbers, tomatoes,
potatoes, and beans.
Vegetables that must be heavily irrigated
(These crops are not suitable for dry gardens.)
Bulb Onions (for fall harvest)
Celeriac
Celery
Chinese cabbage
Lettuce (summer and fall)
Radishes (summer and fall)
Scallions (for summer harvest)
Spinach (summer)
Chapter 5
How to Grow It with Less Irrigation: A--Z
First, a Word About Varieties
As recently as the 1930s, most American country folk still did not
have running water. With water being hand-pumped and carried in
buckets, and precious, their vegetable gardens had to be grown with
a minimum of irrigation. In the otherwise well-watered East, one
could routinely expect several consecutive weeks every summer
without rain. In some drought years a hot, rainless month or longer
could go by. So vegetable varieties were bred to grow through dry
spells without loss, and traditional American vegetable gardens were
designed to help them do so.
I began gardening in the early 1970s, just as the raised-bed method
was being popularized. The latest books and magazine articles all
agreed that raising vegetables in widely separated single rows was a
foolish imitation of commercial farming, that commercial vegetables
were arranged that way for ease of mechanical cultivation. Closely
planted raised beds requiring hand cultivation were alleged to be
far more productive and far more efficient users of irrigation
because water wasn't evaporating from bare soil.
I think this is more likely to be the truth: Old-fashioned gardens
used low plant densities to survive inevitable spells of
rainlessness. Looked at this way, widely separated vegetables in
widely separated rows may be considered the more efficient users of
water because they consume soil moisture that nature freely puts
there. Only after, and if, these reserves are significantly depleted
does the gardener have to irrigate. The end result is surprisingly
more abundant than a modern gardener educated on intensive,
raised-bed propaganda would think.
Finding varieties still adapted to water-wise gardening is becoming
difficult. Most American vegetables are now bred for
irrigation-dependent California. Like raised-bed gardeners,
vegetable farmers have discovered that they can make a bigger profit
by growing smaller, quick-maturing plants in high-density spacings.
Most modern vegetables have been bred to suit this method. Many new
varieties can't forage and have become smaller, more determinate,
and faster to mature. Actually, the larger, more sprawling heirloom
varieties of the past were not a great deal less productive overall,
but only a little later to begin yielding.
Fortunately, enough of the old sorts still exist that a selective
and varietally aware home gardener can make do. Since I've become
water-wiser, I'm interested in finding and conserving heirlooms that
once supported large numbers of healthy Americans in relative
self-sufficiency. My earlier book, being a guide to what passes for
ordinary vegetable gardening these days, assumed the availability of
plenty of water. The varieties I recommended in [i]Growing
Vegetables West of the Cascades[i] were largely modern ones, and the
seed companies I praised most highly focused on top-quality
commercial varieties. But, looking at gardening through the filter
of limited irrigation, other, less modern varieties are often far
better adapted and other seed companies sometimes more likely
sources.
Seed Company Directory*
Abundant Life See Foundation: P.O. Box 772, Port Townsend, WA 98368
_(ABL)_
Johnny's Selected Seeds: Foss Hill Road, Albion, Maine 04910 _(JSS)_
Peace Seeds: 2345 SE Thompson Street, Corvallis, OR 97333 _(PEA)_
Ronninger's Seed Potatoes: P.O. Box 1838, Orting, WA 98360 _(RSP)_
Stokes Seeds Inc. Box 548, Buffalo, NY 14240 _(STK)_
Territorial Seed Company: P.O. Box 20, Cottage Grove, OR 97424
_(TSC)_
*Throughout the growing directions that follow in this chapter, the
reader will be referred to a specific company only for varieties
that are not widely available.
I have again come to appreciate the older style of vegetable--
sprawling, large framed, later maturing, longer yielding,
vigorously rooting. However, many of these old-timers have not seen
the attentions of a professional plant breeder for many years and
throw a fair percentage of bizarre, misshapen, nonproductive plants.
These "off types" can be compensated for by growing a somewhat
larger garden and allowing for some waste. Dr. Alan Kapuler, who
runs Peace Seeds, has brilliantly pointed out to me why heirloom
varieties are likely to be more nutritious. Propagated by centuries
of isolated homesteaders, heirlooms that survived did so because
these superior varieties helped the gardeners' better-nourished
babies pass through the gauntlet of childhood illnesses.
Plant Spacing: The Key to Water-Wise Gardening
Reduced plant density is the essence of dry gardening. The
recommended spacings in this section are those I have found workable
at Elkton, Oregon. My dry garden is generally laid out in single
rows, the row centers 4 feet apart. Some larger crops, like
potatoes, tomatoes, beans, and cucurbits (squash, cucumbers, and
melons) are allocated more elbow room. Those few requiring intensive
irrigation are grown on a raised bed, tightly spaced. I cannot
prescribe what would be the perfect, most efficient spacing for your
garden. Are your temperatures lower than mine and evaporation less?
Or is your weather hotter? Does your soil hold more, than less than,
or just as much available moisture as mine? Is it as deep and open
and moisture retentive?
To help you compare your site with mine, I give you the following
data. My homestead is only 25 miles inland and is always several
degrees cooler in summer than the Willamette Valley. Washingtonians
and British Columbians have cooler days and a greater likelihood of
significant summertime rain and so may plant a little closer
together. Inland gardeners farther south or in the Willamette Valley
may want to spread their plants out a little farther.
Living on 16 acres, I have virtually unlimited space to garden in.
The focus of my recent research has been to eliminate irrigation as
much as possible while maintaining food quality. Those with thinner
soil who are going to depend more on fertigation may plant closer,
how close depending on the amount of water available. More
irrigation will also give higher per-square-foot yields.
_Whatever your combination of conditions, your results can only be
determined by trial._ I'd suggest you become water-wise by testing a
range of spacings.
When to Plant
If you've already been growing an irrigated year-round garden, this
book's suggested planting dates may surprise you. And as with
spacing, sowing dates must also be wisely adjusted to your location.
The planting dates in this chapter are what I follow in my own
garden. It is impractical to include specific dates for all the
microclimatic areas of the maritime Northwest and for every
vegetable species. Readers are asked to make adjustments by
understanding their weather relative to mine.
Gardeners to the north of me and at higher elevations should make
their spring sowings a week or two later than the dates I use. In
the Garden Valley of Roseburg and south along I-5, start spring
plantings a week or two earlier. Along the southern Oregon coast and
in northern California, start three or four weeks sooner than I do.
Fall comes earlier to the north of me and to higher-elevation
gardens; end-of-season growth rates there also slow more profoundly
than they do at Elkton. Summers are cooler along the coast; that has
the same effect of slowing late-summer growth. Items started after
midsummer should be given one or two extra growing weeks by coastal,
high-elevation, and northern gardeners. Gardeners to the south
should sow their late crops a week or two later than I do; along the
south Oregon coast and in northern California, two to four weeks
later than I do.
Arugula (Rocket)
The tender, peppery little leaves make winter salads much more
interesting.
_Sowing date:_ I delay sowing until late August or early September
so my crowded patch of arugula lasts all winter and doesn't make
seed until March. Pregerminated seeds emerge fast and strong.
Sprouted in early October, arugula still may reach eating size in
midwinter.
_Spacing:_ Thinly seed a row into any vacant niche. The seedlings
will be insignificantly small until late summer.
_Irrigation:_ If the seedlings suffer a bit from moisture stress
they'll catch up rapidly when the fall rains begin.
_Varieties: _None.
Beans of All Sorts
Heirloom pole beans once climbed over considerable competition while
vigorously struggling for water, nutrition, and light. Modern bush
varieties tend to have puny root systems.
_Sowing date:_ Mid-April is the usual time on the Umpqua, elsewhere,
sow after the danger of frost is over and soil stays over 60[de]F.
If the earth is getting dry by this date, soak the seed overnight
before sowing and furrow down to moist soil. However, do not cover
the seeds more than 2 inches.
_Spacing:_ Twelve to 16 inches apart at final thinning. Allow about
2[f]1/2 to 3 feet on either side of the trellis to avoid root
competition from other plants.
_Irrigation:_ If part of the garden is sprinkler irrigated, space
beans a little tighter and locate the bean trellis toward the outer
reach of the sprinkler's throw. Due to its height, the trellis tends
to intercept quite a bit of water and dumps it at the base. You can
also use the bucket-drip method and fertigate the beans, giving
about 25 gallons per 10 row-feet once or twice during the summer.
Pole beans can make a meaningful yield without any irrigation; under
severe moisture stress they will survive, but bear little.
_Varieties:_ Any of the pole types seem to do fine. Runner beans
seem to prefer cooler locations but are every bit as drought
tolerant as ordinary snap beans. My current favorites are Kentucky
Wonder White Seeded, Fortrex (TSC, JSS), and Musica (TSC).
The older heirloom dry beans were mostly pole types. They are
reasonably productive if allowed to sprawl on the ground without
support. Their unirrigated seed yield is lower, but the seed is
still plump, tastes great, and sprouts well. Compared to unirrigated
Black Coco (TSC), which is my most productive and best-tasting bush
cultivar, Kentucky Wonder Brown Seeded (sometimes called Old
Homestead) (STK, PEA, ABL) yields about 50 percent more seed and
keeps on growing for weeks after Coco has quit. Do not bother to
fertigate untrellised pole beans grown for dry seed. With the threat
of September moisture always looming over dry bean plots, we need to
encourage vines to quit setting and dry down. Peace Seeds and
Abundant Life offer long lists of heirloom vining dry bean
varieties.
Serious self-sufficiency buffs seeking to produced their own legume
supply should also consider the fava, garbanzo bean, and Alaska pea.
Many favas can be overwintered: sow in October, sprout on fall
rains, grow over the winter, and dry down in June with the soil.
Garbanzos are grown like mildly frost-tolerant peas. Alaska peas are
the type used for pea soup. They're spring sown and grown like
ordinary shelling peas. Avoid overhead irrigation while seeds are
drying down.
Beets
Beets will root far deeper and wider than most people realize--in
uncompacted, nonacid soils. Double or triple dig the subsoil
directly below the seed row.
_Sowing date:_ Early April at Elkton, late March farther south, and
as late as April 30 in British Columbia. Beet seed germinates easily
in moist, cool soil. A single sowing may be harvested from June
through early March the next year. If properly thinned, good
varieties remain tender.
_Spacing:_ A single row will gradually exhaust subsoil moisture from
an area 4 feet wide. When the seedlings are 2 to 3 inches tall, thin
carefully to about 1 inch apart. When the edible part is radish
size, thin to 2 inches apart and eat the thinings, tops and all.
When they've grown to golfball size, thin to 4 inches apart, thin
again. When they reach the size of large lemons, thin to 1 foot
apart. Given this much room and deep, open soil, the beets will
continue to grow through the entire summer. Hill up some soil over
the huge roots early in November to protect them from freezing.
_Irrigation:_ Probably not necessary with over 4 feet of deep, open
soil.
_Varieties:_ I've done best with Early Wonder Tall Top; when large,
it develops a thick, protective skin and retains excellent eating
quality. Winterkeepers, normally sown in midsummer with irrigation,
tend to bolt prematurely when sown in April.
Broccoli: Italian Style
Italian-style broccoli needs abundant moisture to be tender and make
large flowers. Given enough elbow room, many varieties can endure
long periods of moisture stress, but the smaller, woody,
slow-developing florets won't be great eating. Without any
irrigation, spring-sown broccoli may still be enjoyed in early
summer and Purple Sprouting in March/April after overwintering.
_Sowing date:_Without any irrigation at all, mid-March through early
April. With fertigation, also mid-April through mid-May. This later
sowing will allow cutting through summer.
_Spacing:_ Brocoli tastes better when big plants grow big, sweet
heads. Allow a 4-foot-wide row. Space early sowings about 3 feet
apart in the row; later sowings slated to mature during summer's
heat can use 4 feet. On a fist-sized spot compacted to restore
capillarity, sow a little pinch of seed atop a well-and deeply
fertilized, double-dug patch of earth. Thin gradually to the best
single plant by the time three or four true leaves have developed.
_Irrigation:_ After mid-June, 4 to 5 gallons of drip bucket liquid
fertilizer every two to three weeks makes an enormous difference.
You'll be surprised at the size of the heads and the quality of side
shoots. A fertigated May sowing will be exhausted by October. Take a
chance: a heavy side-dressing of strong compost or complete organic
fertilizer when the rains return may trigger a massive spurt of new,
larger heads from buds located below the soil's surface.
_Varieties:_ Many hybrids have weak roots. I'd avoid anything that
was "held up on a tall stalk" for mechanical harvest or was
"compact" or that "didn't have many side-shoots". Go for larger
size. Territorial's hybrid blend yields big heads for over a month
followed by abundant side shoots. Old, open-pollinated types like
Italian Sprouting Calabrese, DeCicco, or Waltham 29 are highly
variable, bushy, with rather coarse, large-beaded flowers,
second-rate flavor and many, many side shoots. Irrigating gardeners
who can start new plants every four weeks from May through July may
prefer hybrids. Dry gardeners who will want to cut side shoots for
as long as possible during summer from large, well-established
plants may prefer crude, open-pollinated varieties. Try both.
Broccoli: Purple Sprouting and Other Overwintering Types
_Spacing:_ Grow like broccoli, 3 to 4 feet apart.
_Sowing date:_ It is easiest to sow in April or early May, minimally
fertigate a somewhat gnarly plant through the summer, push it for
size in fall and winter, and then harvest it next March. With too
early a start in spring, some premature flowering may occur in
autumn; still, massive blooming will resume again in spring.
Overwintering green Italian types such as ML423 (TSC) will flower in
fall if sown before late June. These sorts are better started in a
nursery bed around August 1 and like overwintered cauliflower,
transplanted about 2 feet apart when fall rains return, then, pushed
for growth with extra fertilizer in fall and winter.
With nearly a whole year to grow before blooming, Purple Sprouting
eventually reaches 4 to 5 feet in height and 3 to 4 feet in
diameter, and yields hugely.
_Irrigation:_ It is not essential to heavily fertigate Purple
Sprouting, though you may G-R-O-W enormous plants for their beauty.
Quality or quantity of spring harvest won't drop one bit if the
plants become a little stunted and gnarly in summer, as long as you
fertilize late in September to spur rapid growth during fall and
winter.
Root System Vigor in the Cabbage Family
Wild cabbage is a weed and grows like one, able to successfully
compete for water against grasses and other herbs. Remove all
competition with a hoe, and allow this weed to totally control all
the moisture and nutrients in all the earth its roots can occupy,
and it grows hugely and lushly. Just for fun, I once G-R-E-W one,
with tillage, hoeing, and spring fertilization but no irrigation; it
ended up 5 feet tall and 6 feet in diameter.
As this highly moldable family is inbred and shaped into more and
more exaggerated forms, it weakens and loses the ability to forage.
Kale retains the most wild aggressiveness, Chinese cabbage perhaps
the least. Here, in approximately correct order, is shown the
declining root vigor and general adaptation to moisture stress of
cabbage family vegetables. The table shows the most vigorous at the
top, declining as it goes down.
Adapted to dry gardening Not vigorous enough
Kale Italian broccoli (some varieties)
Brussels sprouts (late types) Cabbage (regular market types)
Late savoy cabbage Brussels sprouts (early types)
Giant "field-type" kohlrabi Small "market-garden" kohlrabi
Mid-season savoy cabbage Cauliflower (regular, annual)
Rutabaga Turnips and radishes
Italian Broccoli (some varieties) Chinese cabbage
Brussels Sprouts
_Sowing date:_ If the plants are a foot tall before the soil starts
drying down, their roots will be over a foot deep; the plants will
then grow hugely with a bit of fertigation. At Elkton I dry garden
Brussels sprouts by sowing late April to early May. Started this
soon, even late-maturing varieties may begin forming sprouts by
September. Though premature bottom sprouts will "blow up" and become
aphid damaged, more, higher-quality sprouts will continue to form
farther up the stalk during autumn and winter.
_Spacing: _Make each spot about 4 feet apart.
_Irrigation:_ Without any added moisture, the plants will become
stunted but will survive all summer. Side-dressing manure or
fertilizer late in September (or sooner if the rains come sooner)
will provoke very rapid autumn growth and a surprisingly large yield
from plants that looked stress out in August. If increasingly larger
amounts of fertigation can be provided every two to three weeks, the
lush Brussels sprouts plants can become 4 feet in diameter and 4
feet tall by October and yield enormously.
_Varieties: _Use late European hybrid types. At Elkton, where
winters are a little milder than in the Willamette, Lunet (TSC) has
the finest eating qualities. Were I farther north I'd grow hardier
types like Stabolite (TSC) or Fortress (TSC). Early types are not
suitable to growing with insufficient irrigation or frequent
spraying to fight off aphids.
Cabbage
Forget those delicate, green supermarket cabbages unless you have
unlimited amounts of water. But easiest-to-grow savoy types will do
surprisingly well with surprisingly little support. Besides, savoys
are the best salad material.
_Sowing date:_ I suggest three sowing times: the first, a succession
of early, midseason, and late savoys made in mid-March for harvest
during summer; the second, late and very late varieties started late
April to early May for harvest during fall and winter; the last, a
nursery bed of overwintered sorts sown late in August.
_Spacing:_ Early-maturing savoy varieties are naturally smaller and
may not experience much hot weather before heading up--these may be
separated by about 30 inches. The later ones are large plants and
should be given 4 feet of space or 16 square feet of growing room.
Sow and grow them like broccoli. Transplant overwintered cabbages
from nursery beds late in October, spaced about 3 feet apart; these
thrive where the squash grew.
_Irrigation:_ The more fertigation you can supply, the larger and
more luxuriant the plants and the bigger the heads. But even small,
somewhat moisture-stressed savoys make very edible heads. In terms
of increased yield for water expended, it is well worth it to
provide late varieties with a few gallons of fertigation about
mid-June, and a bucketful in mid-July and mid-August.
_Varieties:_ Japanese hybrid savoys make tender eating but may not
withstand winter. European savoys are hardier, coarser,
thicker-leaved, and harder chewing. For the first sowing I suggest a
succession of Japanese varieties including Salarite or Savoy
Princess for earlies; Savoy Queen, King, or Savoy Ace for midsummer;
and Savonarch (TSC) for late August/early September harvests.
They're all great varieties. For the second sowing I grow Savonarch
(TSC) for September[-]November cutting and a very late European
hybrid type like Wivoy (TSC) for winter. Small-framed January King
lacks sufficient root vigor. Springtime (TSC) and FEM218 (TSC) are
the only overwintered cabbages available.
Carrots
Dry-gardening carrots requires patiently waiting until the weather
stabilizes before tilling and sowing. To avoid even a little bit of
soil compaction, I try to sprout the seed without irrigation but
always fear that hot weather will frustrate my efforts. So I till
and plant too soon. And then heavy rain comes and compacts my
perfectly fluffed-up soil. But the looser and finer the earth
remains during their first six growing weeks, the more perfectly the
roots will develop.
_Sowing date:_ April at Elkton.
_Spacing: _Allocate 4 feet of width to a single row of carrot seed.
When the seedlings are about 2 inches tall, thin to 1 inch apart.
Then thin every other carrot when the roots are [f]3/8 to [f]1/2
inch in diameter and eat the thinnings. A few weeks later, when the
carrots are about 3/4 to 1 inch in diameter, make a final thinning
to 1 foot apart.
_Irrigation:_ Not necessary. Foliar feeding every few weeks will
make much larger roots. Without any help they should grow to several
pounds each.
_Varieties:_ Choosing the right variety is very important. Nantes
and other delicate, juicy types lack enough fiber to hold together
when they get very large. These split prematurely. I've had my best
results with Danvers types. I'd also try Royal Chantenay (PEA),
Fakkel Mix (TSC), Stokes "Processor" types, and Topweight (ABL). Be
prepared to experiment with variety. The roots will not be quite as
tender as heavily watered Nantes types but are a lot better than
you'd think. Huge carrots are excellent in soups and we cheerfully
grate them into salads. Something about accumulating sunshine all
summer makes the roots incredibly sweet.
Cauliflower
Ordinary varieties cannot forage for moisture. Worse, moisture
stress at any time during the growth cycle prevents proper formation
of curds. The only important cauliflowers suitable for dry gardening
are overwintered types. I call them important because they're easy
to grow and they'll feed the family during April and early May, when
other garden fare is very scarce.
_Sowing date:_ To acquire enough size to survive cold weather,
overwintered cauliflower must be started on a nursery bed during the
difficult heat of early August. Except south of Yoncalla, delaying
sowing until September makes very small seedlings that may not be
hardy enough and likely won't yield much in April unless winter is
very mild, encouraging unusual growth.
_Spacing:_ In October, transplant about 2 feet apart in rows 3 to 4
feet apart.
_Irrigation:_ If you have more water available, fertilize and till
up some dusty, dry soil, wet down the row, direct-seed like broccoli
(but closer together), and periodically irrigate until fall. If you
only moisten a narrow band of soil close to the seedlings it won't
take much water. Cauliflower grows especially well in the row that
held bush peas.
_Varieties:_ The best are the very pricy Armado series sold by
Territorial.
Chard
This vegetable is basically a beet with succulent leaves and thick
stalks instead of edible, sweet roots. It is just as drought
tolerant as a beet, and in dry gardening, chard is sown, spaced, and
grown just like a beet. But if you want voluminous leaf production
during summer, you may want to fertigate it occasionally.
_Varieties:_ The red chards are not suitable for starting early in
the season; they have a strong tendency to bolt prematurely if sown
during that part of the year when daylength is increasing.
Corn
Broadcast complete organic fertilizer or strong compost shallowly
over the corn patch till midwinter, or as early in spring as the
earth can be worked without making too many clods. Corn will
germinate in pretty rough soil. High levels of nutrients in the
subsoil are more important than a fine seedbed.
_Sowing date:_ About the time frost danger ends. Being large seed,
corn can be set deep, where soil moisture still exists even after
conditions have warmed up. Germination without irrigation should be
no problem.
_Spacing_: The farther south, the farther apart. Entirely without
irrigation, I've had fine results spacing individual corn plants 3
feet apart in rows 3 feet apart, or 9 square feet per each plant.
Were I around Puget Sound or in B.C. I'd try 2 feet apart in rows 30
inches apart. Gary Nabhan describes Papago gardeners in Arizona
growing individual cornstalks 10 feet apart. Grown on wide spacings,
corn tends to tiller (put up multiple stalks, each making one or two
ears). For most urban and suburban gardeners, space is too valuable
to allocate 9 square feet for producing one or at best three or four
ears.
_Irrigation:_ With normal sprinkler irrigation, corn may be spaced 8
inches apart in rows 30 inches apart, still yielding one or two ears
per stalk.
_Varieties: _Were I a devoted sweetcorn eater without enough
irrigation, I'd be buying a few dozen freshly picked ears from the
back of a pickup truck parked on a corner during local harvest
season. Were I a devoted corn grower without any irrigation, I'd be
experimenting with various types of field corn instead of sweet
corn. Were I a self-sufficiency buff trying a ernestly to produce
all my own cereal, I'd accept that the maritime Northwest is a
region where survivalists will eat wheat, rye, millet, and other
small grains.
Many varieties of field corn are nearly as sweet as ordinary sweet
corn, but grain varieties become starchy and tough within hours of
harvest. Eaten promptly, "pig" corn is every bit as tasty as
Jubilee. I've had the best dry-garden results with Northstine Dent
(JSS) and Garland Flint (JSS). Hookers Sweet Indian (TSC) has a weak
root system.
Successfully Starting Cucurbits From Seed
With cucurbits, germination depends on high-enough soil temperature
and not too much moisture. Squash are the most chill and moisture
tolerant, melons the least. Here's a failure-proof and simple
technique that ensures you'll plant at exactly the right time.
Cucumbers, squash, and melons are traditionally sown atop a deeply
dug, fertilized spot that usually looks like a little mound after it
is worked and is commonly called a hill. About two weeks before the
last anticipated frost date in your area, plant five or six squash
seeds about 2 inches deep in a clump in the very center of that
hill. Then, a week later, plant another clump at 12 o'clock. In
another week, plant another clump at 3 o'clock, and continue doing
this until one of the sowings sprouts. Probably the first try won't
come up, but the hill will certainly germinate several clumps of
seedlings. If weather conditions turn poor, a later-to-sprout group
may outgrow those that came up earlier. Thin gradually to the best
single plant by the time the vines are running.
When the first squash seeds appear it is time to begin sowing
cucumbers, starting a new batch each week until one emerges. When
the cucumbers first germinate, it's time to try melons.
Approaching cucurbits this way ensures that you'll get the earliest
possible germination while being protected against the probability
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