Conserving Water in the Garden: Designing and Installing a

A.M. VanDerZanden

Water is quickly becoming oneof Oregon’s most critical naturalresources. As the state’s populationincreases and urban areas expand,water use and water rights arebecoming increasingly contentiousissues.

Typically, about 30 to 40 percentof urban water use is for outdooractivities. In addition to landscapemaintenance, outdoor water useincludes washing cars, driveways,and sidewalks, and filling swim-ming pools and children’s watertoys.

When installing a new landscape,there are several things you can doto reduce the amount of water itwill need in the future. Many ofthese suggestions are based on theconcept of “xeriscaping,” a termcoined in the 1980s to describewater-efficient landscaping. Keysteps to establishing a successfulwater-efficient landscape include:

• Start with a landscape plan.

• Improve your soil.

• Select appropriate plants.

• Get your plants off to a goodstart.

• Choose the most appropriateirrigation system.

• Water wisely.

• Mulch.

• Take care of your plants.

Ann Marie VanDerZanden, ExtensionMaster Gardener state coordinator,Oregon State University.

Conserving Water in the Garden

Designing and Installing a New Landscape

Research has shown that thesewater-saving guidelines can reducelandscape water use by 60 to 80percent.

Start with alandscape plan

A water-efficient landscapebegins with a plan. If you arefamiliar with the principles oflandscape design, you might wantto draw your own plan. Anotheroption is to hire a professional tohelp with this critical step. In anyevent, think about who will useyour landscape (adults, children,pets), how the landscape will beused (formal entertaining or infor-mally), and what existing elementsyou want to keep.

In your design, group plantsbased on the amount of water theyneed. This will prevent you fromoverwatering the drought-tolerantspecies and underwatering thosethat need more water.

If you include hard surfaces suchas patios or walkways, use perme-able materials that allow water tosoak into the soil. Examples includestone and gravel. Another option isto grade the site so that runoff iscaptured or redirected into thelandscape where plants can use it.

Improve your soilMost new residential sites have

very poor soil. During construction,most of the topsoil is removed, the

remaining soil is compacted byheavy equipment, and constructionrubble is buried. A soil test will tellyou whether nutrients are lacking.Dollar for dollar, soil improvementis the best investment you can maketo ensure healthy plants and waterconservation.

Organic matter such as compost,shredded bark, or peat adds nutri-ents, increases the soil’s ability toabsorb and store water, andincreases air spaces in the soil. As aresult, plant roots can penetrate thesoil more easily and grow moredeeply. In addition, water soaks intothe soil instead of running off thesurface.

For tree, shrub, and flower beds,till 2 to 4 inches of organic matterinto the entire planting area ratherthan amending individual plantingholes. This will create a betterenvironment for root growth.

Turfgrass grows well in most soiltypes and rarely requires additionalorganic matter. As long as theexisting soil is tilled to a depth of8 inches, turf should grow well. Toprevent runoff, make sure the finalgrade doesn’t slope steeply towarda road or sidewalk.

EC 1530 • May 2001$1.00

Archival copy. Information is out of date. For current information, see OSU Extension Catalog: https://catalog.extension.oregonstate.edu/em9125

2 • Conserving Water in the Garden

Select appropriateplants

Many sources list low-water-useor drought-tolerant plants, but thecriteria used in developing theselists vary greatly. The most impor-tant thing is to select trees, shrubs,groundcovers, and perennials thatare adapted to your region’s soiland climate.

A good idea is to look for plantsthat are native to your area. How-ever, just because a plant is nativedoes not necessarily mean it isdrought-tolerant. Likewise, manynonnative plants are well adapted toour region. In general, speciesnative to Mediterranean climatesare suitable for western Oregon. Ineastern and central Oregon, plantsnative to the high desert RockyMountain plateau make goodchoices.

Most turfgrass species used inOregon have similar water require-ments. Ecolawns are a low-wateralternative to traditional turf. Theycontain a mix of broadleaf plants(clover, English daisy, and yarrow)and grasses (generally perennialryegrass). Ecolawns provide manyof the benefits of traditional turf,including recreation, dust and noiseabatement, and temperature mod-eration, but require less irrigation.

Note: It is very difficult toestablish a new lawn during adrought. The soil needs to be kept

Automated sprinkler systems areespecially prone to encouragingwaste. Studies show that peoplewith automated undergroundirrigation systems use up to twice asmuch water as those wateringmanually with hoses and sprinklers.The convenience of an automatedsystem makes it easy to overwaterbecause you pay less attention toyour landscape.

Water wiselyPeople waste water; plants don’t.

Landscape water loss typicallyoccurs in two ways:

• Water is applied too rapidly andruns off the soil surface ratherthan soaking into the soil.

• Water is applied to bare soilsurfaces and evaporates.

Applying the right amount ofwater, at the right time, and in theright way is the most importantthing you can do to conserve water.

Watering new trees, shrubs,and groundcovers

If it doesn’t rain, most trees,shrubs, and groundcovers benefitfrom a once-a-month thoroughwatering during the growingseason. The majority of tree andshrub feeder roots (those that takeup water and nutrients from thesoil) are in the top 12 inches of soiland extend as much as one and ahalf times past the canopy diameter(Figure 1). To be most effective,apply water in this area. Saturatethe area to a depth of 8 to 10 inches.Figure 2 shows how long this willtake with various soil types.

You can use a drip system withindividual emitters or a soaker hoselaid throughout the area. Anotheroption is a garden hose with a slowstream of water. For larger trees andshrubs, you will need to move thehose around in order to get goodcoverage. This technique might takeseveral hours for large trees.

moist as the grass germinates, andthe new lawn will need wateralmost daily at first. It’s much betterto wait until the rainy season oruntil you have adequate watersupplies for irrigation.

Get your plants off to agood start

Choose healthy plants and plantthem correctly to get your water-wise garden off to a good start.Consult a nursery, your countyExtension office, or reference booksfor planting instructions. All plantsrequire supplemental water andsome extra attention during thefirst, and possibly the second,growing season. See “Waterwisely” at right for more informa-tion.

Choose the mostappropriate irrigationsystem

Wise watering involves applyingwater slowly, deeply, infrequently,and directly to the root system. As aresult, water soaks into the soilrather than running off the surfaceor evaporating. The type of water-ing system you choose can make abig difference in how efficientlyyou water.

Tree, shrub, and flower beds, aswell as vegetable gardens, are mosteffectively irrigated with drip ortrickle systems. Some drip systemshave individual emitters spacedalong a hose. Soaker hoses, on theother hand, slowly release wateralong their entire length. Anotheroption is a garden hose with a slowstream of water.

Sprinklers are much less efficientbecause they lose water to evapora-tion and apply water to areas whereit is not needed. In some cases,however, sprinklers might be theonly alternative.


New Landscapes • 3

Watering young lawnsHow much and how often are the

two biggest questions associatedwith watering newly establishedlawns. Newer lawns are less able towithstand drought than well estab-lished lawns. To maintain a lush,green lawn, apply 1 to 11⁄2 inches ofwater during the dry season. Formost soil types, you should waterone to three times per week in orderto apply the right amount of waterand avoid runoff from applying toomuch water too quickly.

Water infrequentlyand deeply

By thoroughly soaking the rootzone, you will encourage roots todevelop deep in the soil, wheremoisture is held for a long time.These deep roots will help the plantendure drought better. Frequent,shallow watering encourages plantsto develop shallow root systems,which make them susceptible toeven moderate water shortages.

As the growing seasonprogresses and your plants developdeep roots, you can graduallylengthen the time betweenwaterings.

Maintain wateringequipment

To maximize efficiency, keepequipment in good shape. This is

especially important with automaticsprinkler systems. Repair or replacebroken or damaged nozzles orheads, ensure that the timingmechanism and rainfall shutoffs areworking, and make sure you knowhow much water is being applied.Check your system weekly andadjust the days and run times asneeded to avoid overwatering.

Water at nightor in early morning

Less water is lost to evaporationearly and late in the day whentemperatures are lower, humidity ishigher, and the air is calmer. Thedisadvantage of watering before orafter daylight is that you won’t seeyour system operate, so you will notknow if you are overwatering orunderwatering unless you checkyour plants and soil periodically.

MulchWater is lost when it evaporates

from exposed soil. Applying a 3- to5-inch layer of mulch to tree, shrub,

and flower beds can significantlyreduce water evaporation. Varioustypes of mulch are available,including organic mulches (woodchips, shredded bark, compost) orinorganic types (lava rock, riverrock, landscape fabrics). In additionto reducing water evaporation,mulch can suppress weed growth,prevent soil compaction, andmoderate soil temperatures.

Take care of your plantsNo landscape is maintenance-

free. In order to enjoy the benefitsfrom the hard work you put intodesigning and installing your water-wise landscape, you must care for itproperly.

PruningNew trees and shrubs generally

need minimal pruning just toremove diseased or broken limbs.

MowingNew lawns need regular mowing

(once a week during the growingseason if necessary) to maximizeturf density and prevent excessevaporation from the soil surface.See Table 1 for proper mowingheights for various types of grass.Mow at the upper end of the rangeto encourage maximum rootdevelopment, which will slightlyimprove drought tolerance. (SeeTable 1, page 4).

It usually is not necessary todethatch or aerate a new lawn untilits second year. (See EC 1018,Removing Thatch and AeratingLawns, for more information.)Dethatching and aerating estab-lished turf will help it develop adeeper root system and make itbetter able to withstand drought.

FertilizingProper fertilizing can conserve

water. During a water shortage,reduce or eliminate fertilization oftrees and shrubs. As a result, theFigure 1.—The feeder roots extend to

11⁄2 times the diameter of the canopy.

main feederroot zone

dripline

Figure 2.—Infiltration rates for sandyloam and clay loam soil. Silt loam soilabsorbs water at a rate between thesetwo extremes.

Sandy loam Clay loam

1 in

2 in

3 in

4 in

5 in

6 in

2 hours

4 hours

6 hours

8 hours

10 hours

12 hours

4 hours

8 hours

12 hours

16 hours

20 hours

24 hours


plants will grow more slowly anduse less water.

Fertilize your lawn in April tomaximize root development andenhance general plant vigor. Apply1 to 11⁄2 lb N/1,000 sq ft. If severedrought develops, avoid fertilizingduring summer. Fertilize in the fallat a rate of 11⁄2 to 2 lb N/1,000 sq ftto help turf recover rapidly andminimize weed encroachment.

For more informationDeer-resistant Ornamental Plants,

EC 1438. 75¢

Gardening with Composts, Mulches,and Row Covers, EC 1247. $1.00

Maintaining a Healthy Lawn inWestern Oregon, EC 1521. $1.50

Plant Materials for Landscaping: AList of Plants for the PacificNorthwest, PNW 500. $2.50

Removing Thatch and Aerating Lawns,EC 1018. No charge.

Selecting, Planting, and Caring for aNew Tree, EC 1438. $2.00

Southwestern Oregon Tree SelectionGuide for Coos, Curry, Douglas,Jackson, and Josephine Counties,EC 1505. $5.50

Sustainable Gardening: The Oregon-Washington Master GardenerHandbook, EM 8742. $20.00

11⁄2 to 2 inches 1⁄2 to 1 inch*

Table 1.—Mowing height

• Perennial ryegrass• Fine fescue• Tall fescue• Kentucky bluegrass

• Bentgrasses (alone or in amixture)

• Annual bluegrass• Roughstalk bluegrass

*Although the optimum height is 1⁄2 to 1 inch, acceptable turf can be maintained atheights up to 11⁄2 inch. With a mowing height over 2 inches, the turf quality dropsdramatically.

We offer discounts on orders of 100or more copies of a single title. Pleasecall 541-737-2513 for price quotes.

You may order up to six no-chargepublications without charge. If yourequest seven or more no-chargepublications, include 25 cents for eachpublication beyond six.

Available from countyoffices of the OSUExtension ServiceThere may be a charge for photocopy-

ing these publications.

Conserving Water in the Garden:Caring for an Established Land-scape.

Conserving Water in the Garden:Growing a Vegetable Garden.

El Riego en Los Huertos y Jardines(Watering Vegetable and FlowerGardens), EM 8765-S.

World Wide WebYou can access our Publications and

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To order copies of the abovepublications, or additional copies ofthis publication, send the complete titleand series number, along with a checkor money order for the amount listed,to: Publication Orders, Extension &Station Communications, Oregon StateUniversity, 422 Kerr Administration,Corvallis, OR 97331-2119 (Fax: 541-737-0817).

© 2001 Oregon State University. This publication may be photocopied or reprinted in its entirety for noncommercial purposes.

Produced and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Extension work is a cooperative program ofOregon State University, the U.S. Department of Agriculture, and Oregon counties. Oregon State University Extension Service offerseducational programs, activities, and materials—without regard to race, color, religion, sex, sexual orientation, national origin, age,marital status, disability, and disabled veteran or Vietnam-era veteran status. Oregon State University Extension Service is an EqualOpportunity Employer.

Published May 2001.

SummaryWith a little planning and work, it’s easy to save water in your

landscape. Keep these tips in mind:

• Select plants that are adapted to your growing region.

• Group plants according to water use.

• Know your soil type and improve its water-holding capacity.

• Mulch.

• Select an efficient watering system.

• Understand how and when to water.

• Keep your irrigation system in top working order.

Drought cycles will continue to occur, and Oregon’sincreasing population will strain already limited water supplies evenmore. Planning now for the future of your landscape is an importantand environmentally sound decision to make.

Using water wisely benefits everyone!


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Conserving Water in the Garden: Designing and Installing a