Landscape Water Conservation: Principles of Xeriscape - New Mexico State University


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Landscape Water Conservation: Principles of Xeriscape - New Mexico State University

  1. 1. Landscape Water Cooperative Extension Service M EX IC O S TA N EWConservation College of Agriculture and TE Home Economics Y U N IV T E RSIPrinciples of XeriscapeGuide H-707Curtis W. Smith, Extension Horticulture Specialist This publication is scheduled to be updated and reissued 7/05. A surprising amount of water is used in the well adapted, mulches that suppress weeds andhome landscape. Studies have shown that as conserve water, and drip irrigation to make themuch as 70 percent of water from a municipal most use of water, these landscapes can havewater system can be attributed to residential use. color and fragrance with only monthly or sea-In addition to municipal water sources, a percent- sonal gardening chores. Gardeners who like toage of water from private sources or wells also spend time in the garden can design a xeriscapegoes to residential use. Of water used at homes, to be as labor intensive as a highly maintainedalmost half is used to maintain the landscape. traditional garden, but use much less water. There The problem is that while we live in New is a xeriscape for every gardener.Mexico, we have traditionally landscaped with Xeriscape is not a landscape style or gardenplants native to England, Japan, the East Coast of design. Xeriscape is a concept of water conserva-the United States, and other regions with much tion that may be applied to landscapes of anyhigher precipitation. To successfully grow these style, from traditional to English, Japanese,plants, we must supplement the natural precipita- Southwestern, and others. They may be formal ortion with our limited surface and groundwater. natural looking. The principles used to developThe use of plants with high water demands is not xeriscapes are good horticultural practices ap-our only landscaping option; fortunately, neither plied to our unique desert removing plants from the landscape. Our landscapes may remain beautiful and pro-ductive if we use water efficiently and if we uselandscape plants that require less water. A sec- SEVEN XERISCAPE PRINCIPLESondary benefit is that plants with low water re-quirements are frequently adapted to the alkaline 1- Planning and Designsoils characteristic of New Mexico and other dryregions. Landscapes using these water-efficient 2- Efficient Irrigationplants are often called xeriscapes. The concept of xeriscape was developed in 3- MulchDenver, Colorado, in response to water shortages.“Xeros” is a Greek word that means “dry.” 4- Soil PreparationXeriscape refers to a landscape that uses littlesupplemental water. It does not refer to a dry, 5- Appropriate Turfbarren landscape, nor is a xeriscape a “no mainte-nance” landscape. Like traditional landscapes, a 6- Water-Efficient Plant Materialxeriscape may be designed to minimize labor orto require frequent care. Many people appreciate 7- Appropriate Maintenancebeautiful landscapes, but have limited time tospend tending a garden. By using plants that are To find more resources for your business, home, or family, visit the College of Agriculture and Home Economics on the World Wide Web at
  2. 2. Xeriscape incorporates seven water- water-use zones have the greatest need for irriga- conserving principles: tion, but it is wise to plan irrigation even in the low-water-use zone to allow for new planting, 1) Planning and design. changes, and years of severe drought. 2) Efficient irrigation systems, properly The irrigation system—whether automatic, designed and maintained. manual, or hoses moved as needed—also is an 3) Use of mulch. integral part of landscape planning. It is the foun- 4) Soil preparation. dation around which the plantings are designed. 5) Appropriate turf. The water-use zones—low, moderate, and 6) Water-efficient plant material. oasis—should be separate from each other, and 7) Appropriate maintenance. each managed independently. With in-ground ir- rigation systems, each zone should be under a A good landscape and garden begins with a separate valve.good design. Water conservation in the garden The water should be applied as efficiently ascan be maximized if it is considered in the initial possible. Sprinkler systems are appropriate in ar-planning phase. Xeriscapes can be divided into eas of turf, but drip, bubbler, and micro-sprayzones with different water requirements. An “oa- systems or soaker hoses are more appropriate forsis,” a zone with the highest water use, is usually shrubs, trees, and annual and perennial plantings.where people spend more time. The patio area Efficient irrigation applies water where it isand perhaps the entry area are candidates for the needed, not where it will be wasted and benefitoasis. An oasis receives more water and, as a re- only weeds.sult, is cooler. This area also may require moremaintenance and usually will be the landscape’s Mulch provides a cover over the soil, reducingmost colorful area . evaporation, soil temperature, and erosion. It also Beyond the oasis is a transition zone of moder- limits weed growth and competition for waterate water use. The transition zone contains plants and nutrients. Landscape mulch materials vary inthat require less frequent irrigation and usually their suitability for various uses.requires less maintenance. Further away may be a Impermeable plastic mulch has a function inlow-water-use zone, which requires no supple- the landscape, but is very often misused. It maymental water or very infrequent irrigation during be used in areas where the soil must be kept dry,prolonged dry periods. Designing the landscape for example, next to a foundation where ter-with areas of differing water demands is called miticides have been applied and where you are“hydrozoning.” channeling harvested water from one area to an- “Found water” or “harvested water” that runs roofs and paving during storms can be used to Otherwise, permeable weed barriers, bark,reduce the need for supplemental irrigation. Roof gravel, and other porous mulches are better be-runoff can be directed to the oasis or other areas, cause they allow water and oxygen to pass todrastically reducing the need for supplemental plant roots. Dust will eventually collect over theirrigation in the moderate- and low-water-use weed barrier fabrics and allow growth of somezones. Because water harvesting requires grading weeds, so it is not a perfect solution, but these po-to channel and detain runoff, it should be planned rous fabrics are useful for weed control when thewhen the landscape is designed. bark or gravel covering it is less than 3 to 4 inches thick, or annual weed potential is great. Irrigation is necessary in a xeric landscape, at Organic mulches keep the soil moist and re-least during the first few years while the plants’ flect less heat. They work well with plantsroot systems are developing. Following establish- adapted to cooler microclimates. Bark mulchment, irrigation may still be necessary depending should not be used on steep slopes or in drainageon the landscape design and plants’ needs. In ways because it washes away in heavy rains.New Mexico, many landscapes need irrigation Some plants native to very well drained soilsfor at least a portion of the planted area for the grow better in gravel mulches. Remember, rocklife of the garden. The oasis and the moderate- mulch becomes very hot in our climate and can Guide H-707 • Page 2
  3. 3. injure or limit growth of some plants. Ultimately, that needs less water such as buffalograss, bluethe mulch should be shaded by landscape plants grama, or bermuda grass. If the area is only forthat will provide environmental cooling. Using appearance, other ground cover plants may begravel mulch alone as a landscape element may more appropriate and may be irrigated more effi-result in increased home cooling bills and require ciently. Choose the best plants for each purposegreater weed control efforts. by carefully defining your needs and purposes before selecting specific plants. Soil preparation is an important part of suc-cessful xeriscaping and gardening. When done Plants that require less water are becomingprior to planting, soil testing can help determine more readily available in the nurseries. There arewhich plants are best adapted to the site and many very attractive plants for use in water-wisewhich amendments are appropriate for improving landscapes. While you may use many of your oldthe soil for the selected plants. In the oasis and favorites in the oasis zone, there is a wide varietymoderate-water-use zones, adding compost in- of colorful, fragrant, and beautiful plants for thecreases the soil’s water-holding capacity. In the less irrigated part of the landscape. Many havelow-water-use zone, soil preparation may only long blooming seasons and attractive leaves.consist of rototilling to loosen the soil and reduce Some provide autumn interest with colorful foli-the soil compaction associated with building con- age and fruit, while others offer winter intereststruction in planting areas. Loosening the soil im- with their fruit, seed stalks, and winter colorsproves root development and allows better infil- ranging from silver, to gray, to many differenttration of water and air needed by plants’ roots. green and brown shades.This is important in all water-use zones. How- Xeric plants depend on the formation of exten-ever, since soil disturbance promotes the germi- sive root systems to effectively gather water fornation of weed seeds, limit tilling to areas being proper growth. While they may look unimpres-planted. sive in nursery containers, they rapidly become beautiful plants in the landscape. One of the most controversial and misunder-stood of the xeriscape principles is the concept of Maintenance cannot be forgotten, even in aappropriate turf. Turfgrasses have a place in the xeriscape. While many gardeners find the timelandscape, even the xeriscape. Turf is easy to spent gardening very relaxing, people with lessmaintain, although it requires more frequent care time or other interests may prefer a landscape thatthan many other landscape plants. Turf provides a requires minimal time working in the garden. Theplay surface for children and pets. It is an impor- design will determine the required maintenance.tant element in cooling the local environment, Any garden will require some maintenance: prun-reducing erosion, and preventing glare from the ing, removing trash that has blown into the land-sun. Other ground cover plants can perform these scape, occasional weeding and pest management,functions—except providing a play area. Con- checking that the irrigation system is functioningsider where and how large a turf area is desired, properly, and adjusting automatic irrigation sys-how it will be used, and during which seasons it tems as the seasons change.will be used. You are then prepared to limit turfto useful spaces and determine which grasses will Xeriscaping offers a way to have beautiful, liv-best serve your needs. In northern New Mexico able landscapes without excess water use. It al-and higher elevations of the state, cool-season lows areas close to us to be cooler and hospitable,grasses are best for areas used extensively as play while investing less water on parts of the land-areas, especially if this use extends into the early scape in which we spend less time. Even lower-spring and late fall. Fescue or a fescue-bluegrass water-use areas can be very attractive if the sevenmixture is appropriate for these areas. xeriscape principles are employed. Using If the use is light or mostly in the warmer xeriscape makes our landscapes more compatiblemonths and in southern New Mexico, use a grass with our New Mexico environment. Guide H-707 • Page 3
  4. 4. New Mexico State University is an equal opportunity/affirmative action employer and educator. NMSU and the U.S. Department of Agriculturecooperating.Reprinted July 2000 Las Cruces, NM 5C Guide H-707 • Page 4