Water conservation in the landscape can be enhanced with proper design. When we think of design we usually think about budget, needs of the family, personal plant preferences, style of the home, and maintenance. But one of the most important factors is water requirements of the plant material .
A water conserving landscape groups plants with similar water requirements together. The principles of a water efficient landscape are also the principals that provide the best growing conditions for plant material. Dr. Doug Welsh says in his book, Xeriscape Gardening , "You won't mix roses with cacti, moisture loving perennials with rock garden flowers or willows with sagebrush for the simple reason that the water that must be lavished on the one will be wasted on, or may even kill or seriously injure, the other." By zoning plants, you can have a few moisture-loving plants in your landscape, and still conserve water.
The maximum number of zones you can reasonably use in the average home landscape is three. We call them the mini-oasis, the transition zone, and the natural zone.
The "Mini-Oasis" is usually next to the home and close to such areas as the entryway, patio or deck, and the pool area. Here higher water use plants are placed adjacent to outdoor living areas where they can be appreciated, provide a cooling effect, and can receive regular watering. This is where you typically find ground covers and annual flowers.
The "Transition Zone" should be planted with material that requires only occasional watering. This area would be ideal for perennial flowers, tender woody shrubs, vines, and turf areas, and is usually placed farther from the house.
The "Natural Zone" is usually the perimeter of the landscape and in low activity areas. The material here requires little watering and should be able to thrive on natural rainfall most of the year. In this area you usually find the tougher woody shrubs, vines, and trees.
You can also identify "microclimates" within your landscape. Microclimates are created by areas of moisture, sun, shade, air movement, and heat. For example, reflected light from south and west facing structures creates high temperatures which increases the loss of water from nearby plantings. This may create a mini-desert in your yard, even though the area is close to the house in what you might consider an "oasis zone." Deciduous shade trees and groundcovers strategically planted in these exposures reduce temperatures in summer, yet allow sunlight to enter in the winter.
Sloping northern exposures are best planted to tolerate very low water conditions caused by rapid runoff, sun, and wind. A shady north exposure provides a protected environment that requires less water.
Moist micro-climates are sometimes created in the usually hot west or southern yard by irrigation and other water runoff, drainage swales, or areas surrounding gutter basins. Water-loving plants can be grown in these microclimates.
Several microclimates exist within every landscape. As plants grow and provide shade or screen, microclimates change accordingly.
Some areas just aren't plant-friendly. Those are the places for "hardscapes" - decorative elements such as decks, patios, mulched areas, or other types of attractive non-living material.
You don't have to be starting from scratch to plant a water efficient landscape. Using the principles outlined above, you can gradually change a high water use landscape to a WaterWise one by making a master plan and changing out plant material over several years. Over time, you will find the variety and challenge of combining plant material into zones creates a more exciting and variety filled landscape than the traditional designs that use more water.