Gardening Without Irrigation: or without much, anyway

S >> Steve Solomon >> Gardening Without Irrigation: or without much, anyway

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_Varieties:_ For winter squash, all the vining winter varieties in
the C. maxima or C. pepo family seem acceptably adapted to dry
gardening. These include Buttercup, Hubbard, Delicious, Sweet Meat,
Delicata, Spaghetti, and Acorn. I wouldn't trust any of the newer
compact bush winter varieties so popular on raised beds. Despite
their reputation for drought tolerance C. mixta varieties (or cushaw
squash) were believed to be strictly hot desert or humid-tropical
varieties, unable to mature in our cool climate. However, Pepita
(PEA) is a mixta that is early enough and seems entirely unbothered
by a complete lack of irrigation. The enormous vine sets numerous
good keepers with mild-tasting, light yellow flesh.

Obviously, the compact bush summer squash varieties so popular these
days are not good candidates for withstanding long periods without
irrigation. The old heirlooms like Black Zucchini (ABL) (not Black
Beauty!) and warty Yellow Crookneck grow enormous, high-yielding
plants whose extent nearly rivals that of the largest winter squash.
They also grow a dense leaf cover, making the fruit a little harder
to find. These are the only American heirlooms still readily
available. Black Zucchini has become very raggedy; anyone growing it
should be prepared to plant several vines and accept that at least
one-third of them will throw rather off-type fruit. It needs the
work of a skilled plant breeder. Yellow Crookneck is still a fairly
"clean" variety offering good uniformity. Both have more flavor and
are less watery than the modern summer squash varieties. Yellow
Crookneck is especially rich, probably due to its thick, oily skin;
most gardeners who once grow the old Crookneck never again grow any
other kind. Another useful drought-tolerant variety is Gem,
sometimes called Rolet (TSC). It grows an extensive
winter-squash-like vine yielding grapefruit-size, excellent eating
summer squash.

Both Yellow Crookneck and Black Zucchini begin yielding several
weeks later than the modern hybrids. However, as the summer goes on
they will produce quite a bit more squash than new hybrid types. I
now grow five or six fully irrigated early hybrid plants like Seneca
Zucchini too. As soon as my picking bucket is being filled with
later-to-yield Crooknecks, I pull out the Senecas and use the now
empty irrigated space for fall crops.

Tomato

There's no point in elaborate methods--trellising, pruning, or
training--with dry-gardened tomato vines. Their root systems must be
allowed to control all the space they can without competition, so
allow the vines to sprawl as well. And pruning the leaf area of
indeterminates is counterproductive: to grow hugely, the roots need
food from a full complement of leaves.

_Sowing date:_ Set out transplants at the usual time. They might
also be jump started under cloches two to three weeks before the
last frost, to make better use of natural soil moisture.

_Spacing:_ Depends greatly on variety. The root system can occupy as
much space as the vines will cover and then some.

_Irrigation:_ Especially on determinate varieties, periodic
fertigation will greatly increase yield and size of fruit. The old
indeterminate sprawlers will produce through an entire summer
without any supplemental moisture, but yield even more in response
to irrigation.

_Variety:_ With or without irrigation or anywhere in between, when
growing tomatoes west of the Cascades, nothing is more important
than choosing the right variety. Not only does it have to be early
and able to set and ripen fruit when nights are cool, but to grow
through months without watering the plant must be highly
indeterminate. This makes a built-in conflict: most of the sprawly,
huge, old heirloom varieties are rather late to mature. But cherry
tomatoes are always far earlier than big slicers.

If I had to choose only one variety it would be the old heirloom
[Large] Red Cherry. A single plant is capable of covering a 9-to
10-foot-diameter circle if fertigated from mid-July through August.
The enormous yield of a single fertigated vine is overwhelming.

Red Cherry is a little acid and tart. Non-acid, indeterminate cherry
types like Sweetie, Sweet 100, and Sweet Millions are also workable
but not as aggressive as Red Cherry. I wouldn't depend on most bush
cherry tomato varieties. But our earliest cherry variety of all,
OSU's Gold Nugget, must grow a lot more root than top, for, with or
without supplemental water, Gold Nugget sets heavily and ripens
enormously until mid-August, when it peters out from overbearing
(not from moisture stress). Gold Nugget quits just about when the
later cherry or slicing tomatoes start ripening heavily.

Other well-adapted early determinates such as Oregon Spring and
Santiam may disappoint you. Unless fertigated. they'll set and ripen
some fruit but may become stunted in midsummer. However, a single
indeterminate Fantastic Hybrid will cover a 6-to 7-foot-diameter
circle, and grow and ripen tomatoes until frost with only a minimum
of water. I think Stupice (ABL, TSC) and Early Cascade are also
quite workable (and earlier than Fantastic in Washington).

Chapter 6

My Own Garden Plan

This chapter illustrates and explains my own dry garden. Any garden
plan is a product of compromises and preferences; mine is not
intended to become yours. But, all modesty aside, this plan results
from 20 continuous years of serious vegetable gardening and some
small degree of regional wisdom.

My wife and I are what I dub "vegetablitarians." Not vegetarians, or
lacto-ovo vegetarians because we're not ideologues and eat meat on
rare, usually festive occasions in other peoples' houses. But over
80 percent of our calories are from vegetable, fruit, or cereal
sources and the remaining percentage is from fats or dairy foods.
The purpose of my garden is to provide at least half the actual
calories we eat year-round; most of the rest comes from home-baked
bread made with freshly ground whole grains. I put at least one very
large bowl of salad on the table every day, winter and summer. I
keep us in potatoes nine months a year and produce a year's supply
of onions or leeks. To break the dietary monotony of November to
April, I grow as wide an assortment of winter vegetables as possible
and put most produce departments to shame from June through
September, when the summer vegies are "on."

The garden plan may seem unusually large, but in accordance with
Solomon's First Law of Abundance, there's a great deal of
intentional waste. My garden produces two to three times the amount
of food needed during the year so moochers, poachers, guests, adult
daughters accompanied by partners, husbands, and children, mistakes,
poor yields, and failures of individual vegetables are
inconsequential. Besides, gardening is fun.

My garden is laid out in 125-foot-long rows and one equally long
raised bed. Each row grows only one or two types of vegetables. The
central focus of my water-wise garden is its irrigation system. Two
lines of low-angle sprinklers, only 4 feet apart, straddle an
intensively irrigated raised bed running down the center of the
garden. The sprinklers I use are Naans, a unique Israeli design that
emits very little water and throws at a very low angle (available
from TSC and some garden centers). Their maximum reach is about 18
feet; each sprinkler is about 12 feet from its neighbor. On the
garden plan, the sprinklers are indicated by a circle surrounding an
"X." Readers unfamiliar with sprinkler system design are advised to
study the irrigation chapter in Growing Vegetables West of the
Cascades.

On the far left side of the garden plan is a graphic representation
of the uneven application of water put down by this sprinkler
system. The 4-foot-wide raised bed gets lots of water, uniformly
distributed. Farther away, the amount applied decreases rapidly.
About half as much irrigation lands only 6 feet from the edge of the
raised bed as on the bed itself. Beyond that the amount tapers off
to insignificance. During summer's heat the farthest 6 feet is
barely moistened on top, but no water effectively penetrates the dry
surface. Crops are positioned according to their need for or ability
to benefit from supplementation. For convenient description I've
numbered those rows.

The Raised Bed

Crops demanding the most water are grown on the raised bed. These
include a succession of lettuce plantings designed to fill the
summer salad bowl, summer spinach, spring kohlrabi, my celery patch,
scallions, Chinese cabbages, radishes, and various nursery beds that
start overwintered crops for transplanting later. Perhaps the bed
seems too large just for salad greens. But one entire meal every day
consists largely of fresh, raw, high-protein green leaves; during
summer, looseleaf or semiheading lettuce is our salad item of
choice. And our individual salad bowls are larger than most families
of six might consider adequate to serve all of them together.

If water were severely rationed I could irrigate the raised bed with
hose and nozzle and dry garden the rest, but as it is, rows 1, 2, 7,
and 8 do get significant but lesser amounts from the sprinklers.
Most of the rows hold a single plant family needing similar
fertilization and handling or, for convenience, that are sown at the
same time.

Row 1

The row's center is about 3 feet from the edge of the raised bed. In
March I sow my very first salad greens down half this row--mostly
assorted leaf lettuce plus some spinach--and six closely spaced
early Seneca Hybrid zucchini plants. The greens are all cut by
mid-June; by mid-July my better-quality Yellow Crookneck squash come
on, so I pull the zucchini. Then I till that entire row,
refertilize, and sow half to rutabagas. The nursery bed of leek
seedlings has gotten large enough to transplant at this time, too.
These go into a trench dug into the other half of the row. The leeks
and rutabagas could be reasonably productive located farther from
the sprinklers, but no vegetables benefit more from abundant water
or are more important to a self-sufficient kitchen. Rutabagas break
the winter monotony of potatoes; leeks vitally improve winter
salads, and leeky soups are a household staple from November through
March.

Row 2: Semi-Drought Tolerant Brassicas

Row 2 gets about half the irrigation of row 1 and about one-third as
much as the raised bed, and so is wider, to give the roots more
room. One-third of the row grows savoy cabbage, the rest, Brussels
sprouts. These brassicas are spaced 4 feet apart and by summer's end
the lusty sprouts form a solid hedge 4 feet tall.

Row 3: Kale

Row 3 grows 125 feet of various kales sown in April. There's just
enough overspray to keep the plants from getting gnarly. I prefer
kale to not get very stunted, if only for aesthetics: on my soil,
one vanity fertigation about mid-July keeps this row looking
impressive all summer. Other gardens with poorer soil might need
more support. This much kale may seem an enormous oversupply, but
between salads and steaming greens with potatoes we manage to eat
almost all the tender small leaves it grows during winter.

Row 4: Root Crops

Mostly carrots, a few beets. No irrigation, no fertigation, none
needed. One hundred carrots weighing in at around 5 pounds each and
20-some beets of equal magnitude make our year's supply for salads,
soups, and a little juicing.

Row 5: Dry-Gardened Salads

This row holds a few crowns of French sorrel, a few feet of parsley.
Over a dozen giant kohlrabi are spring sown, but over half the row
grows endive. I give this row absolutely no water. Again, when
contemplating the amount of space it takes, keep in mind that this
endive and kohlrabi must help fill our salad bowls from October
through March.

Row 6: Peas, Overwintered Cauliflower, and All Solanaceae

Half the row grows early bush peas. Without overhead irrigation to
bother them, unpicked pods form seed that sprouts excellently the
next year. This half of the row is rotary tilled and fertilized
again after the pea vines come out. Then it stays bare through July
while capillarity somewhat recharges the soil. About August 1, I wet
the row's surface down with hose and fan nozzle and sow overwintered
cauliflower seed. To keep the cauliflower from stunting I must
lightly hand sprinkle the row's center twice weekly through late
September. Were water more restricted I could start my cauliflower
seedlings in a nursery bed and transplant them here in October.

The other half is home to the Solanaceae: tomato, pepper, and
eggplant. I give this row a little extra width because pea vines
run, and I fertigate my Solanaceae, preferring sprawly tomato
varieties that may cover an 8-foot-diameter circle. There's also a
couple of extra bare feet along the outside because the neighboring
grasses will deplete soil moisture along the edge of the garden.

Row 7: Water-Demanding Brassicas

Moving away from irrigation on the other side of the raised bed, I
grow a succession of hybrid broccoli varieties and late fall
cauliflower. The broccoli is sown several times, 20 row-feet each
sowing, done about April 15, June 1, and July 15. The late
cauliflower goes in about July 1. If necessary I could use much of
this row for quick crops that would be harvested before I wanted to
sow broccoli or cauliflower, but I don't need more room. The first
sowings of broccoli are pulled out early enough to permit succession
sowings of arugula or other late salad greens.

Row 8: The Trellis

Here I erect a 125-foot-long, 6-foot-tall net trellis for gourmet
delicacies like pole peas and pole beans. The bean vines block
almost all water that would to on beyond it and so this row gets
more irrigation than it otherwise might. The peas are harvested
early enough to permit a succession sowing of Purple Sprouting
broccoli in mid-July. Purple Sprouting needs a bit of sprinkling to
germinate in the heat of midsummer, but, being as vigorous as kale,
once up, it grows adequately on the overspray from the raised bed.
The beans would be overwhelmingly abundant if all were sown at one
time, so I plant them in two stages about three weeks apart. Still,
a great many beans go unpicked. These are allowed to form seed, are
harvested before they quite dry, and crisp under cover away from the
sprinklers. We get enough seed from this row for planting next year,
plus all the dry beans we care to eat during winter. Dry beans are
hard to digest and as we age we eat fewer and fewer of them. In
previous years I've grown entire rows of dry legume seeds at the
garden's edge.

Row 9: Cucurbits

This row is so wide because here are grown all the spreading
cucurbits. The pole beans in row 8 tend to prevent overspray; this
dryness is especially beneficial to humidity-sensitive melons,
serendipitously reducing their susceptability to powdery mildew
diseases. All cucurbits are fertigated every three weeks. The squash
will have fallen apart by the end of September, melons are pulled
out by mid-September. The area is then tilled and fertilized, making
space to transplant overwintered spring cabbages, other overwintered
brassicas, and winter scallions in October. These transplants are
dug from nurseries on the irrigated raised bed. I could also set
cold frames here and force tender salad greens all winter.

Row 10: Unirrigated Potatoes

This single long row satisfies a potato-loving household all winter.
The quality of these dry-gardened tubers is so high that my wife
complains if she must buy a few new potatoes from the supermarket
after our supplies have become so sprouty and/or shriveled that
they're not tasty any longer.

Chapter 7

The Backyard

Water-Wise Gardener

I am an unusually fortunate gardener. After seven years of
struggling on one of the poorest growing sites in this region we now
live on 16 acres of mostly excellent, deep soil, on the floor of a
beautiful, coastal Oregon valley. My house and gardens are perched
safely above the 100-year flood line, there's a big, reliable well,
and if I ever want more than 20 gallons per minute in midsummer,
there's the virtually unlimited Umpqua River to draw from. Much like
a master skeet shooter who uses a .410 to make the sport more
interesting, I have chosen to dry garden.

Few are this lucky. These days the majority of North Americans live
an urban struggle. Their houses are as often perched on steep,
thinly soiled hills or gooey, difficult clay as on a tiny fragment
of what was once prime farmland. And never does the municipal
gardener have one vital liberty I do: to choose which one-sixth of
an acre in his 14-acre "back yard" he'll garden on this year.

I was a suburban backyard gardener for five years before deciding to
homestead. I've frequently recalled this experience while learning
to dry garden. What follows in this chapter are some strategies to
guide the urban in becoming more water-wise.

Water Conservation Is the Most Important First Step

After it rains or after sprinkler irrigation, water evaporates from
the surface until a desiccated earth mulch develops. Frequent light
watering increases this type of loss. Where lettuce, radishes, and
other shallow-rooting vegetables are growing, perhaps it is best to
accept this loss or spread a thin mulch to reduce it. But most
vegetables can feed deeper, so if wetting the surface can be
avoided, a lot of water can be saved. Even sprinkling longer and
less frequently helps accomplish that. Half the reason that drip
systems are more efficient is that the surface isn't dampened and
virtually all water goes deep into the earth. The other half is that
they avoiding evaporation that occurs while water sprays through the
air between the nozzle and the soil. Sprinkling at night or early in
the morning, when there is little or no wind, prevents almost all of
this type of loss.

To use drip irrigation it is not necessary to invest in pipes,
emitters, filters, pressure regulators, and so forth. I've already
explained how recycled plastic buckets or other large containers can
be improvised into very effective drip emitters. Besides, drip tube
systems are not trouble free: having the beds covered with fragile
pipes makes hoeing dicey, while every emitter must be periodically
checked against blockage.

When using any type of drip system it is especially important to
relate the amount of water applied to the depth of the soil to the
crops, root development. There's no sense adding more water than the
earth can hold. Calculating the optimum amount of water to apply
from a drip system requires applying substantial, practical
intelligence to evaluating the following factors: soil water-holding
capacity and accessible depth; how deep the root systems have
developed; how broadly the water spreads out below each emitter
(dispersion); rate of loss due to transpiration. All but one of
these factors--dispersion--are adequately discussed elsewhere in
_Gardening Without Irrigation._

A drip emitter on sandy soil moistens the earth nearly straight down
with little lateral dispersion; 1 foot below the surface the wet
area might only be 1 foot in diameter. Conversely, when you drip
moisture into a clay soil, though the surface may seem dry, 18
inches away from the emitter and just 3 inches down the earth may
become saturated with water, while a few inches deeper, significant
dispersion may reach out nearly 24 inches. On sandy soil, emitters
on 12-inch centers are hardly close enough together, while on clay,
30-or even 36-inch centers are sufficient.

Another important bit of data to enter into your arithmetic: 1 cubic
foot of water equals about 5 gallons. A 12-inch-diameter circle
equals 0.75 square feet (A = Pi x Radius squared), so 1 cubic foot
of water (5 gallons) dispersed from a single emitter will add
roughly 16 inches of moisture to sandy soil, greatly overwatering a
medium that can hold only an inch or so of available water per foot.
On heavy clay, a single emitter may wet a 4-foot-diameter circle, on
loams, anywhere in between, 5 gallons will cover a 4-foot-diameter
circle about 1 inch deep. So on deep, clay soil, 10 or even 15
gallons per application may be in order. What is the texture of your
soil, its water-holding capacity, and the dispersion of a drip into
it? Probably, it is somewhere in between sand and clay.

I can't specify what is optimum in any particular situation. Each
gardener must consider his own unique factors and make his own
estimation. All I can do is stress again that the essence of
water-wise gardening is water conservation.

Optimizing Space: Planning the Water-Wise Backyard Garden

Intensive gardening is a strategy holding that yield per square foot
is the supreme goal; it succeeds by optimizing as many growth
factors as possible. So a raised bed is loosened very deeply without
concern for the amount of labor, while fertility and moisture are
supplied virtually without limit. Intensive gardening makes sense
when land is very costly and the worth of the food grown is judged
against organic produce at retail--and when water and nutrients are
inexpensive and/or available in unlimited amounts.

When water use is reduced, yield inevitably drops proportionately.
The backyard water-wise gardener, then, must logically ask which
vegetable species will give him enough food or more economic value
with limited space and water. Taking maritime Northwest rainfall
patterns into consideration, here's my best estimation:

Water-Wise Efficiency of Vegetable Crops

(in terms of backyard usage of space and moisture)

EFFICIENT ENOUGH

Early spring-sown crops: peas, broccoli, lettuce, radishes, savoy
cabbage, kohlrabi

Overwintered crops: onions, broccoli cauliflower,
cabbage, favas beans

Endive Kale

Garden sorrel

Indeterminate tomatoes

Giant kohlrabi

Parsley--leaf and root

heirloom summer squash (sprawly)

Pole beans

Herbs: marjoram, thyme, dill, cilantro, fennel, oregano

Root crops: carrots, beets, parsnips

MARGINAL

Brussels sprouts (late)

Potatoes

Determinate tomatoes

Rutabagas

Eggplant

Leeks

Leeks

Savoy cabbage (late)

Peppers, small fruited

INEFFICIENT

Beans, bush snap

Peppers, bell

Broccoli, summer

Radishes

Cauliflower

Scallions, bulb onions

Celery

Sweet corn

Lettuce

Turnips

Have fun planning your own water-wise garden!

More Reading

About the Interlibrary Loan Service

Agricultural books, especially older ones, are not usually available
at local libraries. But most municipal libraries and all
universities offer access to an on-line database listing the
holdings of other cooperating libraries throughout the United
States. Almost any book published in this century will be promptly
mailed to the requesting library. Anyone who is serious about
learning by reading should discover how easy and inexpensive (or
free) it is to use the Interlibrary Loan Service.

Carter, Vernon Gill, and Tom, Dale. _Topsoil and Civilization._

Norman, Okla.: University of Oklahoma Press, 1974.

The history of civilization's destruction of one ecosystem after
another by plowing and deforestation, and its grave implications for
our country's long-term survival.

Cleveland, David A., and Daniela Soleri. _Food from Dryland Gardens:
An Ecological, Nutritional and Social Approach to Small-Scale
Household Food Production. _Tucson: Center for People, Food and
Environment, 1991.

World-conscious survey of low-tech food production in semiarid
regions.

Faulkner, Edward H._ Plowman's Folly._ Norman, Okla.: University of
Oklahoma Press, 1943.

This book created quite a controversy in the 1940s. Faulkner
stresses the vital importance of capillarity. He explains how
conventional plowing stops this moisture flow.

Foth, Henry D. _Fundamentals of Soil Science. _Eighth Edition. New
York: John Wylie & Sons, 1990.

A thorough yet readable basic soil science text at a level
comfortable for university non-science majors.

Hamaker, John. D. _The Survival of Civilization._ Annotated by
Donald A. Weaver. Michigan/California: Hamaker-Weaver Publishers,
1982.

Hamaker contradicts our current preoccupation with global warming
and makes a believable case that a new epoch of planetary glaciation
is coming, caused by an increase in greenhouse gas. The book is also
a guide to soil enrichment with rock powders.

Nabhan, Gary. _The Desert Smells like Rain: A Naturalist in Papago
Indian Country. _San Francisco: North Point Press, 1962.

Describes regionally useful Native American dry-gardening techniques

Russell, Sir E. John. _Soil Conditions and Plant Growth. _Eighth
Edition. New York: Longmans, Green & Co., 1950.

Probably the finest, most human soil science text ever written.
Russell avoids unnecessary mathematics and obscure terminology. I do
not recommend the recent in-print edition, revised and enlarged by a
committee.

Smith, J. Russell. Tree Crops: a Permanent Agriculture. New York:
Harcourt, Brace and Company, 1929.

Smith's visionary solution to upland erosion is growing unirrigated
tree crops that produce cereal-like foods and nuts. Should sit on
the "family bible shelf" of every permaculturalist.

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