Gardening Without Irrigation: or without much, anyway

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

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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.

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