| (Find out more at a Water Efficient Workshop)
About Water Efficient Landscapes
As you plan each area, consider several different arrangements. For example, is a fence, wall or hedge more appropriate for screening and/or security? How much space is needed for active recreation, a vegetable garden or for patio entertaining? Only after these decisions are made should you begin thinking about what plants to use.
A base map is a plan of the property drawn to scale on graph paper showing the location of the house, its orientation to the sun, other structures on the site, unusual features such as stone outcroppings and existing vegetation. Accuracy in the base map will help you determine if your site will accommodate all of your plans. Later it will help to determine the quantity of any construction materials and plants needed.
Catalog Site Characteristics
Next, lay a sheet of tracing paper over the base map and label it "Site Analysis." Use arrows to indicate the direction of desirable views you want to emphasize and undesirable views you want to screen. Use arrows to indicate the drainage patterns of the property, including any low spots or eroded areas. Make plans to correct potential drainage problems before planting. This may require regrading, bringing in additional soil, building retaining walls or shaping terraces. Any changes in the existing landscape should be subtle so that the natural character of the landscape is retained.
Incorporate as many of the natural elements of the site into the design as possible, such as existing trees and shrubs. Undisturbed native plants will not require water for re-establishment and may be more water efficient than new plantings. Note the orientation of the home (i.e., north, south, east, west). This will help determine where to put plants best suited for sun or shade. Areas exposed to direct afternoon sun are likely to dry out more rapidly than those in the shade. In these locations, your plan should include drought-tolerant plants, some method of providing supplemental water or cultural practices that will help conserve moisture.
Incorporate Shade Into the Design
Shade from trees or structures in the landscape keeps the landscape cooler and reduces water loss while creating a comfortable living environment. A shaded landscape can be as much as 20°F cooler than one in the full sun.
A person standing in an open parking lot is bombarded with 1,000 heat units from the sun and another 1,000 heat units reflected from the paved surface. Walking beneath a shade tree provides immediate relief from the sun because the tree acts like an umbrella, blocking light and heat (passive shade). If the tree is growing in moist soil, it will not only block heat but will also dissipate heat by evaporative loss from the leaves (active shade). A moist soil surface also evaporates heat and reduces heat load further. Therefore, a moist landscape with trees can contain one-fourth as much heat as a parking lot in full sun and one-half as much heat as a bone-dry landscape.
In addition to paved areas, shade prevents heat buildup from other hardscape surfaces, such as brick or stucco walls and gravel walks. Whenever possible, try to shade these surfaces. Just as we perspire and lose moisture through our pores, plants transpire and lose moisture through their leaves. A mature oak tree, for example, can dissipate as much heat as four home central air conditioners running 24 hours per day. This evaporative water loss from leaves has a cooling effect on the environment and reduces water loss. Therefore, effective shading makes the landscape more water-efficient, the main objective of water efficient landscape planning.
Effective shade management in a water efficeint type landscape involves using shade to block sunlight from striking the soil surface, to intercept, scatter and reflect radiant energy to protect paved surfaces or masonry structures from direct sunlight. Effective shade management also involves managing wind currents that influence heat flow in the landscape. In addition to trees, structures like trellises, arbors, walls or fences can provide shade. A vine or espalier on these structures improves their shading and cooling effect. See "Durable Plants" for a suggested list of vines.
Plan for Different Use Areas
To begin your plan, overlay the base map and site analysis sheet with another piece of tracing paper. On this sheet indicate the public, private and service areas of your landscape. Consider how these areas will be developed based on space requirements for each activity. The public area is the highly visible area that most visitors see, such as the entry to the home. In a traditional landscape, this area typically receives the most care, including the most water. Therefore, the careful design of this area is important for water conservation. This area can be designed to require minimal water and maintenance without sacrificing quality or appearance. The private area of the landscape, usually the backyard, is where most outdoor activity occurs. It is generally the family gathering area. It may also include a vegetable garden or fruit orchard. The landscape in this area needs to be functional, attractive and durable, but it also should be designed to require less water than the public area of the landscape. The service area is the working or utility area of the landscape, an area usually screened from view and containing such items as garbage cans, outdoor equipment, air-conditioning units or a doghouse. In terms of routine maintenance, this area would be designed to require the least care and water of the three areas.
Establish Water-use Zones
In addition to dividing the landscape into use areas, a Water Efficient Landscape plan further divides the landscape into three water-use zones: high (regular watering), moderate (occasional watering) and low (natural rainfall). An individual landscape may include several of these zones. High water-use zones are small, highly visible areas and highly maintained areas of the landscape, such as the public area and the area around the patio where plants are watered regularly in the absence of rainfall. In the moderate water-use zones, established plants are watered only when they turn a gray-green color, wilt or show other symptoms of moisture stress. Possible plants for this zone include azalea, dogwood, redbud, Japanese maple and many herbaceous perennials.
In the low water-use zones, plants are watered by natural rainfall and would not be irrigated. For greatest water conservation, design as much of your landscape as possible into low water-use zones. Most people are surprised to learn that the majority of our woody ornamental trees and shrubs, turfgrasses, some herbaceous perennials and even some annuals, like vinca and verbena, grow well in low water-use zones where they are not irrigated once they are established. Expect a slight loss of quality during extended dry periods, but don't be alarmed.
Some plants will literally shut down during drought and cease growing. Bermuda grass will go dormant and turn brown during drought, then bounce back with the first rains. Learning to accept this "less than perfect" appearance during dry periods is one of the most difficult obstacles to overcome in a water-conserving landscape. One exception to the water zone rule is newly planted ornamental plants and turfgrasses. These plants require regular irrigation during the establishment period (8 to 10 weeks after planting), regardless of their intended water-use zone. To maximize water savings, concentrate seasonal color beds in areas of the landscape where they can be watered and maintained. Avoid scattering a number of small color beds throughout the landscape.
Now, a new overlay of tracing paper to the base map and sketch your desired water-use zones. The landscape is beginning to take shape and you can visualize the form of the various beds, but construction materials and plants have not yet been identified.
Develop a Master Plan
Once you have settled on a design scheme and a water management arrangement, give form and definition to the various spaces in your plan. With the identification of planting spaces as well as edging materials, groundcovers and paving, the master plan begins to take form. This is a plan showing the final product of your efforts. Straight lines or smooth flowing curves are best -- tight curves or unnecessary bends can be maintenance problems. Use right angles and avoid acute angles that are difficult to maintain and irrigate. Remember that simplicity in the design will ensure easy maintenance and water-use efficiency.
Fit Plants to the Design
Once you achieve the style and overall effect you desire, select plants to fill the assigned spaces. Select plants that complement and accent the good features of the architecture and construction materials rather than overpower them. Group plantings to conform to the shape of plant beds. Avoid rigid formal, geometric plantings as much as possible. A good approach for most residences is to place the larger plants at the corners with some height at the entrance and low plantings in between. Such arrangements focus attention on the entrance. For a pleasing visual effect, use odd number groupings (1, 3, 5) when possible. Use bands of low-growing plants or ground covers to tie together and unify groups of taller shrubs. Place plants at the proper spacing in the landscape to ensure easy maintenance and more efficient use of water.
Select plants that have a size and form that conform to their location without having to be sheared or frequently pruned to keep them in bounds. Plants, like people, grow in all shapes and sizes. If left unpruned, some plants will be tall and thin; others will stay short and spreading. Some will be irregular with open branching; others will be compact with dense foliage. Choose plants with the same shape and ultimate size as the space you want to fill. For example, to plant an area in front of low windows, 2 feet above the ground, select spreading low-growing shrubs with an anticipated height of not more than 2 feet.
Renovation of an Existing Landscape for Improved Water Conservation
The before view illustrates a rather dull landscape with foundation shrubs ringing the house, a hedge along three sides and some native trees along the rear of the property. The redesign of the residence shows expansion of the shrub beds in the public and private areas of the landscape to provide seasonal interest, variety and reduced maintenance. Shade-tolerant ground covers are used under the existing trees on the left side of the front and right rear of the property. A large area in the left rear of the property was made a natural mulch play area for children.
Additional examples of water efficient renovations are shown in "Commercially Designed Water Efficient-type Landscapes: Before and After Renovation." The alteration of an existing landscape to conserve water does not have to be as elaborate as that shown. In many instances, it may be as simple as relocating a few shrubs or flowering trees to more environmentally suitable locations on the property or improving the shape of plant beds to simplify irrigation. Considerable savings can result by converting irrigated areas to ground covers or natural mulch areas. Simply changing management practices and watering habits without making any physical changes in the landscape often can save large amounts of water. For each 1,000 square feet of landscaped area converted from an irrigated to a nonirrigated area, you can save an estimated minimum of $60 per year on water and sewage costs.
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