What is a Xeriscape Design?

Developed in Denver, Colorado in response to water shortages, the xeriscape design method groups plants into three "water requirement zones" for more efficient irrigation. Xeriscapes are means a dry and lifeless -- in fact, a luxuriant oasis zone is included in the plan. Although this design has been promoted as a "no maintenance" landscape, the truth is that, like any other garden, it can be designed for low- or high-maintenance preferences.

The Main Features of the Xeriscape Design

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• Planning and design
• Use of mulch
• Soil preparation
• Appropriate turf

The Xeriscape Zones

A xeriscape garden is divided into three zones: the oasis zone, the transition zone, and the low-water zone.

Zone One: Oasis Zone

The oasis zone is planted closest to the house, usually in an area where people want to sit and enjoy the garden, such as the patio. The area is filled with lush plants that require reqular irrigation (usually once every 2-6 weeks), making this the coolest section of the garden. Potted plants, annual flowerbeds, vegetables and herbs, and a small lawn are all appropriate for a xeriscape oasis zone. This is also the ideal place for a water feature. To bring water to the thirty plants in this zone, drip irrigation is used.

Zone Two: Transition Zone

Beyond the oasis, farther from the house, is a transition zone of moderate water use. This zone will require less frequent irrigation and usually less maintenance. Here should be drought-resistant plants that require deep irrigation (usually once every 12-15 weeks). A drip irrigation system is used in combination with contours such as berms and swales that direct rainwater onto the plants.

Zone Three: Low-water Zone

Farthest from the house is a zone of low water consumption in which no artificial irrigation is needed except in occasional periods of prolonged drought. The idea is to use plants that can survive on rainfall alone. Preferably, native plants will be used. To help the plants along, berms and swales are created to direct rainwater.

Which Plant in Which Zone?

Determinig which plants are right for which zone really depends on the individual garden. Plants that thrive on zone two (transition) levels of irrigation in an open, rural area may need more water in an urban area. Heat from by pavement, concrete walls, and nearby houses may mean these plants now require zone one (oasis) levels of irrigation.

The most accurate way of placing plants into the proper xeriscape zone is to understand that particular plant's water requirements. You'll also need to know who long it takes your irrigation system to penetrate the soil to the depths of the plants' roots.

Agave parryii in the Arizona countryside might do well on rainfall alone and can be planted in zone three (low-water), whereas zinnias will most likely need water once every week or two for an hour using 1 gallon/hour (4 lt/hr ) drip irrigation system and should be placed in zone one (oasis).