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





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