Outdoor water uses, primarily for landscaping, consume an estimated eight billion gallons per day in the US, perhaps as much as one-third of all water use.168 "Xeriscaping" is a well-used term for water-conserving landscaping, the prefix denoting dry. Another term might be "natural landscaping." The essential feature of xeriscaping is to employ regionally appropriate plants and planting techniques (such as mulching) that reduce or eliminate water use except from normal precipitation in the area. If you've ever seen sprinklers on in the midst of a rainstorm, or broad expanses of green lawn highlighting a public building or major office complex in the desert, you'll know something is amiss in our understanding of how to minimize the environmental impacts of landscaping practices. Fortunately, xeriscaping is a major movement today among landscape architects.
Where I live in Tucson, I would be shocked to see a green lawn in front of a new home in a development. In the Tucson area, single family residents use 30 to 50 percent of their water outdoors for landscape watering, swimming pools, spas, evaporative cooling and other such uses.168 The reality of living in a desert has finally caught the popular imagination; as a result, people plant a lot of cactus, mesquite and Palo Verde trees, varieties of succulents and desert wildflowers, living with the seasonality of the dry landscape.
Planting native and adapted species, a typical practice of xeriscaping, has the added advantage of providing food, habitat and shelter for many local birds, insects and small mammals that have evolved in the region. Most state extension services provide information on plant selection for xeriscaping, and most landscape architects know this approach. The harder part is to find someone expert enough in local native plants to introduce and keep them growing in a xeriscaped environment.
Technically, for green buildings xeriscaping can be accompanied by temporary irrigation for the first year, until plants are established. Many practitioners also group plants with similar water requirements, especially in larger areas where different amounts of rainwater can be directed into swales, ponds and waterways. Outside of areas with mild temperatures and abundant rainfall, you will not see much turf in a xeriscape.
The first step in evaluating a xeriscape design is to really know the site: sun, wind, rain, existing vegetation, topography, orientation (south-facing or north-facing, for example) and soils. Plants need to be chosen carefully for their water requirements, shade and sun tolerance, food and shelter value to native wildlife. Group plants in ways that make sense in their natural environment. For example, in the desert young saguaro cacti often grow in the shade of older trees such as mesquite. Put in some mulch and a simple watering system the first year to get the plants established, then let nature take its course.
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