C O N S E R V I N G W A T E R I N T H E G A R D E N

EM 8375 • Reprinted July 1992

Growing a Vegetable GardenR.A. McNeilan

Even in times of a water shortage,you can grow a vegetable garden ifyou use special water-efficientpractices. You might also considersome of these practices if your area’swater is normally in short supply orexpensive—or both.

Flat is bestFor efficient water conservation,

prepare a soil surface for maximumwater penetration. This meansplanting in a flat surface instead ofany combination of raised mounds,beds, or ditches.

The “hill” referred to on a seedpacket usually means a grouping ofseeds rather than a raised area. Araised area, once it has dried, is verydifficult to wet again. Water runsaway from the root zone of the plantand is wasted.

Using fertilizersManaging soil tilth to include

additional organic matter willpromote water penetration andretention. Organic material caninclude plant residue from gardenplants, leaves, straw, manure,sawdust, bark, etc. Apply theseadditions annually.

Adequate fertility levels will helpproduce crops that require limitedwater. A fertilizer such as 5-10-10 atthe rate of 1/2 to 3/4 cup per 10 feetof row will supply this fertility.Placing fertilizer in a band 2 inchesbelow and 2 inches to the side of theseed will provide maximum effi-ciency. (The crop will get a betterstart, and weeds between the rowswon’t get as much encouragement.)Excess fertilizer can cause burning ofthe roots if soil moisture is low.

Omit some vegetables?Consider omitting certain vege-

tables when water is in short supply:• Poor-yield crops for space and

water used: sweet corn, soybeans,peas.

• Poorly adapted crops in cool areas:okra, sweet potatoes, watermelons.

• Crops susceptible to severe attacksby insects or diseases, and difficultto count on for good production ofedible vegetables: Brussels sprouts,turnips, and those vegetablesattacked by curly-top in easternOregon.

Cultivating and weedingA number of good gardening

practices will help in conservationefforts. For example, don’t plant insoils that are too cold—seeds won’tgrow satisfactorily, and water will notbe properly absorbed.

From the start, weed control is veryimportant in your garden. Weedswaste water, and they compete withvegetable plants for nutrients andsunlight. For maximum water use,maintain excellent weed control inyour garden.

Cultivation of the soil should beshallow. Deep tillage or hoeing notonly damages plant roots but alsoallows moisture to evaporate. Veryshallow rototilling, or weed controlwith a scuffle or push hoe, will bemore appropriate. (A scraping actionwith the scuffle hoe is best.)

Plastic mulchesWarm-season crops like tomatoes,

peppers, and melons benefit from aplastic mulch. This type of mulch willgreatly conserve moisture and help

speed maturity. Place a 2- to 21/2-footstrip along the row with its edgesburied with soil. Plant the transplantor seed through an X-cut in theplastic at the desired location.

Black plastic will prevent weedgrowth, conserve soil moisture, andwarm the soil for faster crop matur-ity. Clear plastic also conservesmoisture and will warm the soil morethan black plastic. However, weedsmay grow under clear plastic—soblack is preferable for most garden-ing situations west of the Cascades.

Once the soil has warmed, youcould use organic mulches like grassclippings or straw to conservemoisture and control weeds. Becausethese materials shade the ground(and thus reduce soil temperatures),plants may grow more slowly if youapply the mulch to the garden beforethe soil warms. You can use newspa-pers, but they’re somewhat unsightly.

When you’re deciding whether touse organic mulches, remember thatmany straws and hays can be asource of weed contamination for thegarden. Bark and sawdust are weed-free materials.

Using water wiselyRoot zones. When you use water,

try to concentrate it in the plants’ rootzone. The less water you applybetween the rows where roots can’tuse it, the less water you lose toevaporation. In addition, water froma sprinkler won’t all reach the soilsurface because of evaporation—a

Ray A. McNeilan, Extension agent (homeand urban horticulture), MultnomahCounty, Oregon State University.

loss of up to 25%. Several techniqueswill help place the water in the rootzone where it’s needed:1. For crops like squashes and cucumbers that are grown in a group, bury a juice or coffee can with the bottom at root level. Punch holes in the bottom of the can, so the water you pour in it

will reach the roots with a mini-mum of loss.

2. You can irrigate individual plantslike tomatoes, peppers, andeggplants in the same manner,using a slightly smaller can.Punch the holes in the can onlyon the side next to the plant.

3. A “trickle” or “drip” irrigationsystem permits water to ooze

from a continuous soaker, or it emits water at a given location.

You can buy kits with variouscomponents to supply water in

this fashion at garden stores.Canvas soakers, or inverted

sprinkler hoses near the plants,perform the same function. (These

types of delivery can save you many gallons of water.)

Sprinkler irrigation. If you usethis system, minimize water lossesby:1. using a sprinkler that will cover the garden only, not the surround ing area;2. watering early in the morning

when air is cool, wind is low, andwater pressure is better on munici-pal systems; or

3. using a rate of application thatpermits all water to soak in and

not run off the garden area.

Soak the soil. When you water,thoroughly soak the soil to a depth of6 to 8 inches and do it less frequently.Depending on stage of growth andtemperatures, a 5- to 7-day intervalmay be enough.

Try closer rows. A smaller areagardened more intensively willproduce more vegetables in relationto water usage. You can grow quite afew vegetables much closer togetherthan traditional 2 1/2- to 3-foot rows.You can place radishes, onions, beets,carrots, etc., in rows as close as 1 footapart. This way, you make better useof the water you apply in the rootzone. In addition, a shaded soil losesless water by evaporation to theatmosphere.

Plant vegetables and flowerstogether. You could plant vegetablesin some flower beds and borders. Thewatering schedule for the food crops

Extension Service, Oregon State University,Corvallis, O.E. Smith, director. This publica-tion was produced and distributed infurtherance of the Acts of Congress of May 8and June 30, 1914. Extension work is acooperative program of Oregon State Univer-sity, the U.S. Department of Agriculture, andOregon counties.

Oregon State University Extension Serviceoffers educational programs, activities, andmaterial—without regard to race, color,national origin, sex, age, or disability—asrequired by Title VI of the Civil Rights Act of1964, Title IX of the Education Amendments of1972, and Section 504 of the Rehabilitation Actof 1973. Oregon State University ExtensionService is an Equal Opportunity Employer.

will be adequate for the perennialshrubs. Red cabbage, rhubarb, chard,leaf lettuce, and compact tomatoesare decorative as well as usefulplants.

Container planting of vegetableswill use more water than in-groundgardening. Containers dry muchfaster than garden beds and rows.

Use waste water? Some peoplehave advocated using bath water onplants. Present health regulations,however, prohibit use of watercontaining soaps or detergents.

Note: Check with your healthdepartment before you use any wastewater. Some areas have regulationsprohibiting surface application ofwaste water.

Here’s help. You can find addi-tional water conservation ideas ingardening books such as Ortho’sWeather-Wise Gardening (Westernedition) and Gardening Shortcuts,available at most garden supplystores.