A GUIDE TO HIGH DESERT LANDSCAPING - University Of Arizona

WINDLANDSCAPING A NEW HOMEWINDThe population of the High Desert hasincreased dramatically over the last twentyyears. Many people have moved here from otherareas to enjoy cleaner air and a peaceful, lesshurried lifestyle. Climatic conditions in the HighDesert are harsher and more extreme than marineclimates, offering a landscaping challenge.New homes are often purchased on relativelylarge lots with little or no landscaping provided.This section is divided into Designing andInstalling Your Landscape and Designing andInstalling Your Irrigation System to assist withthese important issues.Designing and Installing Your LandscapeFirst, design your landscape on paper. Beginby listing the functions your landscape shouldprovide your family, such as play areas for smallchildren, entertainment areas and shade. Next,decide where these functional areas should belocated for maximum pleasure and use. Considerwind patterns, sunlight, accessibility, and othersite specific conditions when creating yourlandscape plan.Here are some useful facts to consider whendesigning your landscape:5 When selecting plants, consider functionfirst and foremost. Next, decide onacceptable maintenance levels. Groupplants according to irrigation needswhenever possible. Plants that are placed by themselves anddirectly exposed to the sky are morefrost-prone than those protected by shadefrom other plants, patios or otherstructures. Always select plants according to howtheir mature size and appearance fit intoyour design. Do not select plants basedon initial appearance in immature stagesof growth. In hot, dry, windy weather, shade-lovingplants, such as azaleas and begonias, losewater faster than they can absorb it. Keepthem in partial shade. Consider adding interest and color toyour landscape by rotating annualflowers in small “investment zones”near your house. Large growing trees should be planted atleast 20 feet from your house. This givestree roots adequate space to grow andprevents structural damage to your home.Also avoid planting trees closer than fivefeet from sidewalks and driveways.Once your family has agreed on an acceptable landscape design, specific plants may beselected. The Plant List at the back of this booklists many climatically adapted choices for theHigh Desert and includes color photos. Keep inmind that other suitable plants do not appear onthe list due to space limitations.

SOIL AMENDMENTSSoil amendments are sometimes beneficial tolandscape plantings. If used, they should be addedbefore planting, so plant roots are not disturbed.There are two types of soil amendments: nonchemical and chemical. Descriptions andrecommended uses follow:Use only decomposed products as soilamendments. Freshly cut turfgrass, green manureand similar products should be composted first. Arule of thumb is: if it's still recognizable, it's notready for use!Chemical Soil AmendmentsNon-chemical Soil AmendmentsExamples include decomposed products (eithercommercially prepared or from backyard compostpiles) such as compost, lawn clippings, and peatmoss. These soil amendments are mixed withlandscape soil to increase water-holding capacityand improve soil structure. Since they supply onlysmall amounts of nutrients, soil amendments shouldnot be thought of as fertilizers.While amendments are often useful, there arecases where you may be better off without them.Here are some general guidelines concerning nonchemical soil amendments:Most soils in the High Desert are sandy loams.As long as your soil is a consistent texture withoutlayers or hardpan, you do not need to amend it toconserve water or achieve adequate plant growth.This is particularly true in areas to be planted withturfgrass or trees. By properly schedulingirrigations, you can avoid water waste withoutadding amendments.Soil amendments are useful in vegetable andflower gardens, and in shrub plantings. Amendmentsshould be mixed thoroughly with original soil, atleast 40% by volume. Amended soil should be atleast 1 foot deep for gardens and at least 1-1/2 feetdeep for shrub plantings.Gypsum (CaSO4) is useful for reclaimingsoil with high levels of sodium. It will not correctproblems caused by layered soils. A simple testwill help determine whether your soil wouldbenefit from gypsum.Remove the bottom of two coffee cans. Replace the bottoms with window screen, placing apaper towel filter on top of each screen. Fill eachcan with one pint of soil, and allow it to dry. Addone tablespoon of gypsum to one coffee can,mixing it thoroughly into the soil. Set each coffeecan on an empty cup; fill each can with tap water.Collect drainage water until ½ pint or more iscollected from the gypsum-treated sample. If morethan twice as much water has drained from theamended soil, your solid contains excess sodium.Likely, a chemical amendment such as gypsumwill help reclaim the soil.Gypsum contains calcium which replaces thesodium. A sodium salt is formed in the processwhich must be leached from the soil. Gypsumshould be applied as deep as the ultimate rootingdepth of the species to be planted. A soil test willindicate how much gypsum is necessary.Soil AlkalinityMost High Desert soils are alkaline, with pH'sbetween 7.5 - 9.0. A soil test is useful to determine soilpH. Alkaline soils tie up necessary plant elements,such as phosphorus, manganese, zinc and iron. Even ifthese elements exist in the soil, they are not availableto your plants until the soil is neutralized. A pH of 7.0is neutral, although most plants grow well in pHsbetween 6.0 and 7.5.Ammonium sulfate is a popular and usefulfertilizer in the High Desert. It serves a dual purposeby providing both nitrogen and sulphur. The sulphurreduces pH. A soil test is useful to determine properrates of sulphur. If is usually necessary to applysulphur over a relatively long time period sincereducing alkalinity takes repeated sulphur applications.Never add only a few inches of soil amendment.This causes layering and reduces downwardmovement of water. It is better to not amend a soilthan to add only a shallow layer.6

MULCHING & FERTILIZERSRecommended planting procedures shouldalways be followed to help ensure long-termsuccess. Numerous general gardening booksoffer information on how to plant.MulchRight after planting, it is useful to applymulch to the top of soil around trees, shrubs andflowers. Mulch reduces soil evaporation, providesweed control and buffers soil temperature. Manymaterials are suitable, including fabric cloth(alone or beneath other products), rocks, gravel,wood chips and compost. High Desert winds mayblow mulch away. Use mulch under a rock layeror cover with landscape netting to reduce erosion.Mulches should be placed several inchesaway from tree trunks and should extend severalfeet outward. Remember to irrigate for a longenough time to allow the water to penetrate intothe soil through the mulch.FertilizersDo not fertilize at planting time! Wait untilplants are established. Then follow therecommendations in the maintenance section ofthis booklet.MAKE YOUR OWN COMPOSTInstead of sending organic materials to landfills,compost your yard clippings and use the mulchto improve your garden by adding organicmaterial to your soil, increasing its ability tohold water.Composting is the breakdown of organicmaterial by fungi and bacteria. The process ofcomposting builds heat, which destroys weedseed, insects and disease. In the High Desert,this normal heat build-up combined with hightemperatures can result in fire. Keep compostpiles away from structures.What can you compost? Good compost caninclude any organic material such as: grassclippings, weeds, tree leaves, livestock manures,hedge clippings, straw, and vegetable wastesfrom the kitchen.Wood chips will decompose very slowly whilesucculent material will break down relativelyquickly7Steps:1. Stack compost material four to six feet high.Keep in place with wire or wood.2. Turn the compost pile every month to even thedecomposing process.3. Moisten the pile as needed to keep as wet as asqueezed out sponge.4. Add a handful of high nitrogen fertilizer withevery large amount of organic matter added.5. Composting will be complete in six weeks to sixmonths, depending upon heat and the size of thematerials.6. Place the composted material on the soil surfacearound plants, or mix into new planting areasand backfill soils. It is especially good to use inflowerbeds, soil mixes, or with container plantsand vegetables.

DESIGNING AND INSTALLING YOURIRRIGATION SYSTEMOnce you have designed your landscape butbefore you plant, you should design and install anirrigation system. It should be based on the typeand location of your landscape plants. You candesign and install the system yourself, or hire anexpert. This decision depends on your expertiseand the time you have to devote to the project.This section is intended to give an overviewof irrigation approaches for High Desert gardens.Nuts and bolts information on how to install yourown irrigation system can be obtained by askingfor free irrigation publications from any of thewater agencies that sponsored this publication(check the inside back cover for how to contactthem), or talk to your local nursery, irrigationspecialist or landscape professional.Irrigation components should be based onyour landscape needs and the capabilities of yourhome plumbing system. The following are threethings you should do initially, whether you designand install the system yourself or hire aprofessional:1.2.3.Draw your landscape plan on graphpaper. Include all trees, shrubs, turfgrassand groundcover areas, as well ashardscapes. Mark the location of theservice line to your home.Use a pressure gauge to determine thestatic water pressure. Do this at theoutside faucet when no water is runninginside or outside. Take several readingsthroughout the day and use the lowest fordesigning your system.Determine the size of the service linerunning from the street to your house andrecord the size of your water meter.Here are some design and installation tips: Divide areas to be irrigated into squaresand rectangles whenever possible. Install sprinklers in corners first. Then,install around the perimeter and finally inthe center as needed for full coverage. Space sprinkler heads for head-to-headcoverage. Select sprinkler types (impulse, closedcase rotors, spray heads and bubblers)according to size and use of area. Irrigate shrubs, trees and flower bedswith drip systems whenever possible. Select sprinkler heads according toavailable pressure. If your static waterpressure is less than 40 psi, use plasticheads rather than brass. Several circuits are necessary due towater pressure and volume limitations.Each circuit is controlled by one valve.Group control valves together in aconvenient location for easy access. Consider installing an automatic timer.Select a timer that is compatible withyour irrigation scheduling needs.8

RELANDSCAPING FOR THE HIGH DESERTThe aim of this booklet is to guide HighDesert residents toward beautiful landscapes thatare water-efficient and appropriate for the HighDesert environment. But many people buyexisting homes and inherit gardens planned byothers. Also many homeowners may havegardens that they developed before they fullyrealized the importance of water awareness.In some cases, existing landscapes may beinappropriate for the High Desert, may be highwater use or may not fit your family's needs. Ifso, there can be many benefits to relandscaping.These include: Decreasing the maintenance time foryour landscape.Matching the landscape to your desireduses for it.Lowering costs for both water andindoor energy use.Developing a more natural and pleasinglandscape.Doing your part to conserve HighDesert water resources.KEYS TO YOUR GARDEN MAKEOVER 1.2. 3.9Decreasing your water use.Inspect and repair your irrigation system.Develop an appropriate watering schedule forexisting plantings.Evaluate your needs. Will they be met byrelandscaping? If so, develop plans that include: Planting new materials, including turf tomeet only functional needs. Placing trees and shrubs for summershade and winter sun.Installing hardscape patios or decks forrecreational uses. Developing plant zones and using dripirrigation where possible.Replacing labor-intensive plants withlow-water-use shrubs and groundcovers. Using mulches to help soil retain water.

A 3-YEAR GUIDE FOR RELANDSCAPINGYear OneMany typical home gardens have large areasof lawn bordered by a few shrubs, with ascattering of two or three trees planted in thelawn. Begin by identifying your goals. Turfgrassshould be kept to areas where it is needed for playor recreation. Hardscapes such as covered patiosand decking provide a good surface for outdoorrecreation. Shrubs and groundcovers arebeautiful, low maintenance alternatives to lawnareas. Trees can provide shade in summer andhelp keep homes cool. Create intimate, privateareas using paths, open areas and garden furnitureplaced under shady trees.1. Decide which elements you want toinclude in your garden.2. Make a plan that shows lawn, plantingsand hardscape. Remember, when yourethink your landscape, considerfunction first and foremost. Group plantsaccording to irrigation needs wheneverpossible.3. Plan your irrigation system so that itmeets the needs of your newlandscape.Year Two1. Begin by installing all hardscape areas.This will prevent you from disturbingyour plantings with construction.Hardscapes require no water and canresult in dramatic water savings for yourlandscape.2. Renovate your existing irrigation systemto accommodate your new plan. Replaceportions of your spray sprinkler systemwith a drip irrigation system for trees andshrubs. Drip irrigation is the most waterefficient, is healthiest for plants andreduces run off and erosion.3. Plant deciduous trees on the south andwest sides of buildings to provide summershade but allow winter sun. Evergreentrees and shrubs placed on the north sideof your home or business help retainwinter warmth.Year Three1. Adjust irrigation for new plantings.2. Add more shade trees, areas of mulch,and lawn furniture for private areas.3. Add groundcover for extra color.4. Add shrubs for beauty and a morenatural looking landscape.10

MAINTAINING AN ESTABLISHED LANDSCAPEWhether you recently purchased a pre-ownedhome or have lived in the same home for manyyears, the following recommended landscapemaintenance practices are essential for plant healthand water conservation.Many recommended practices that favor planthealth also conserve water. The following is anoverview of these practices. TREES Keep turfgrass and other vegetation at least20 inches from tree trunks. This promotesfaster tree growth and reduces competitionfor water. Do not routinely fertilize landscape trees.Over-fertilization (particularly nitrogen) canresult in excessive growth, requiringadditional water. Fertilize if nutrientdeficiencies appear. Apply mulch around trees, but keep itseveral inches away from tree trunks. Mulchreduces soil evaporation, buffers soiltemperature and reduces weeds. Rememberto apply water long enough to soak throughthe mulch layer into the roots. 11Avoid soil compaction around trees, whichresults in poor water infiltration and runoff.Control weeds around trees. They competefor water.Irrigate trees separately from surroundingvegetation whenever possible. Drip systems(which include mini-sprinklers) are excellentfor this purpose. Consider using a waterbudget as outlined on page 13.Irrigate trees based on seasonal waterdemand. Preliminary research indicates thatmany species do well on about the sameamount of water as warm season turfgrasses,or even less.Prune trees when necessary. Removedead and diseased wood, crossed limbs,suckers and weak vertical growth.Pruning stimulates additional shootgrowth, increasing the water requirement.SHRUBS Do not routinely fertilize shrubs.Overfertilization (particularly nitrogen) canresult in excessive growth, requiringadditional water. Fertilize if nutrientdeficiencies appear.Apply mulch around shrubs.Avoid soil compaction around shrubs.Control weeds around shrubs.Irrigate shrubs separately from surroundingvegetation whenever possible. Dripsystems work well for this purpose.Most shrubs are water-efficient onceestablished. Consider using a water budgetmethod (see page 13). Irrigate based onseasonal water demand.

MAINTAINING YOURIRRIGATION SYSTEMGROUNDCOVERS Do not routinely fertilize groundcovers.Fertilize once annually if nutrient deficienciesappear. Avoid soil compaction.Control weeds.Irrigate groundcovers based on seasonal waterdemand. Consider using a water budgetmethod (see page 13). Preliminary researchindicates that many species do well whenreceiving about the same amount of water aswarm-season turfgrass.TURFGRASSES Remove thatch if over one-half inch thick.Control weeds.Fertilize moderately, applying low end ofrecommended rates. If conditions dictate,stop fertilizing altogether, except forpotassium, which promotes droughtresistance. Aerate as necessary to avoid soilcompaction. Follow the lawn watering guide on page 13.Maintaining an effective irrigation system canprevent more water waste than any other landscapepractice. Yet, it is often the most overlookedmethod of conserving water.Take time to examine your irrigation system atleast once each month. Check for: Broken sprinkler headsSunken sprinkler headsUnmatched sprinkler headsNon-vertical sprinkler headsClogged drip emittersIf brown spots occur in turfgrass areas, conducta “can test” to check for spray uniformity, asdescribed in the “Lawn Watering Guide.”Often brown spots occur because trees orshrubs were added after the initial sprinkler systemwas designed and installed. In this case, add extraheads if the existing heads cannot be adjustedaccordingly.Brown spots may also be caused by femaledogs, disease or insects. These problems can beidentified by a professional consultant.12

1.2.3.4.5.6.7.13Determine the water-holding capacity ofyour soil. As discussed earlier, most HighDesert soils are sandy loam by definition.Both hold between 1 to 2 inches of waterper foot of soil. For setting your waterbudget, use the low end: Each foot of soilholds 1 inch of water.Consider the ultimate rooting depth ofshrubs and trees: Allow 1-1/2 feet ofwater per shrub and 3 feet per tree.To determine the total water budget pertree, multiply 1 inch of water-holdingcapacity per each foot of soil depth: 1inch of water/foot x 3 feet 3 inches ofwater.To determine the total water budg

Beautiful, successful, water-efficient landscaping in the High Desert is the result of thoughtful attention and proper information. "A Guide to High Desert Landscaping" provides accurate and prac-tical information to help local residents conserve water while creating an attractive and useful landscape.