Prepared by:
M. A. Powell, Extension Specialist
Horticultural Science
T. M. Disy
Information Specialist
Publication Number:AG-508-2
Last Electronic Revision: March 1996 (JWM)
This publication leads you through seven steps for planning and designing an attractive, useful, and water-efficient landscape, known as a xeriscape. As you plan each area of your landscape, consider several different arrangements. Ask yourself the following types of questions:
1. Start with a Base Map.
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. An example of a base map is shown in Figure 1. Accuracy in the base map helps determine if your site can accommodate all of your plans. It also helps in deciding on the quantity of construction materials and plants needed.
2. Analyze Site Characteristics.
Lay a sheet of tracing paper over the base map and label it "Site Analysis" (Figure 2). Use arrows to indicate the direction of the views you want to emphasize, undesirable views you want to screen, and 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, installing drainage tiles, 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. Undisturbed native plants do not require the additional water that new plants need for establishment. Because they are already adapted to the site, native plants may also be more water efficient than plants added to the landscape.
Note the orientation of the home to the sun to determine where to locate 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, and cultural practices that help conserve moisture.
3. Incorporate Shade into the Design.
Shade from trees or structures in the landscape keeps the landscape cooler, reduces water loss, and helps create a comfortable living environment. A shaded landscape may be 20oF cooler than a landscape in full sun.
The effects of shade on soil moisture are shown in Figure 3. As the figure shows, 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 as the tree acts like an umbrella, blocking 400 heat units. If the tree is growing in moist soil, it not only blocks heat but also dissipates heat by evaporative loss from the leaves. A moist soil surface also evaporates water and thereby consumes energy (heat) and reduces heat load further. This cooling effect reduces water loss in the area beneath the tree. Shade also prevents heat build-up in other hard landscape surfaces, such as brick or stucco walls, driveways, and gravel walks. Therefore, a moist landscape with trees feels cooler.
In addition to trees, structures like trellises, arbors, walls, and fences can provide shade. A vine or espalier on these structures improves their shading and cooling effects. Shading makes the landscape more water efficient, which is the main objective of xeriscape planning.
4. Plan Areas for Different Uses.
To begin your plan, place a piece of tracing paper over the base map and site analysis sheet. On this sheet indicate the public, private, and service areas of your landscape (Figure 4). Consider how these areas will be developed based on the space requirements for each activity.
The public area is the area that most visitors see, such as the entrance to the home. In a traditional landscape, this area usually receives the most care, including the most water. It is, however, possible to design this area 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 place and may also include a vegetable garden or fruit orchard. The landscape here needs to be functional, attractive, and durable; it should also be suitable for conservative water use.
The service area is the working or utility area of the landscape, an are a that is usually screened from view and may contain items such as garbage cans, outdoorequipment, air-conditioning units, or a dog house. In terms of routine maintenance, this area would be designed to require the least care and water.
5. Establish Water-Use Zones.
In addition to dividing the landscape into use areas, a xeriscape plan further divides the landscape into three water-use zones — high (regular watering), moderate (occasional watering), and low (natural rainfall). Several of these zones may be included within an individual landscape.
High-water-use zones are small, highly visible and highly maintained are as 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 show symptoms of moisture stress, such as wilting or changing color. Possible plants for this zone include azalea, dogwood, redbud, Japanese maple, and many herbaceous perennials. In the low-water-use zones, plants receive no water except natural rainfall.
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 North Carolina's woody ornamental trees and shrubs, turfgrasses, some herbaceous perennials, and even some annuals, like vinca and verbena, grow well in low-water-use zones.
Don't be alarmed by a slight loss of quality during extended dry periods . Some established plants literally shut down during drought and cease growing. Most turfgrasses go dormant and turn brown during drought, then bounce back with the first rain. Learning to accept this "less than perfect" appearance during dry periods is one of the most difficult parts of creating a water-conserving landscape.
One exception to the water-use 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 zones.
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, add another sheet of tracing paper over the base map and sketch your desired water-use zones (Figure 5). The landscape is beginning to take shape and you can visualize the form of the various beds.
6. 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, ground covers, and paving, the master plan begins to take shape (Figure 6).
In the landscape, just as in nature, smooth, flowing curves are best; tight curves or unnecessary bends can be maintenance problems. Avoid sharp angles that are difficult to maintain and irrigate. Remember that simplicity in the design will ensure easy maintenance and water-use efficiency.
7. Choose Plants that Fit the Design.
Once you achieve the style and overall effect you want, it is time to select plants to fill the assigned spaces. It is important to choose plants that complement and accent the good features of your 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. Plants grouped in large beds, informal balance, and free-flowing curves are popular and practical design concepts.
Place plants to ensure easy maintenance and efficient use of water. It is important to space plants far enough apart so that they can achieve their mature size without being crowded. Crowding not only increases your costs, but also results in long-term maintenance problems and increases the potential for water stress.
Surface Area (sq ft) Zone Before After Lowa 0 3,403 Moderateb 5,788 3,538 Highc 3,662 2,509 Total irrigated area 9,450 6,047 aLow = not irrigated; bModerate = irrigated occasionally; cHigh = irrigated regularly.
Select plants that have a size and form that conform to their location without having to be sheared or pruned frequently. 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 2 to 3 feet. Ground-cover-type plants fit particularly well in areas such as this. Modern trends in landscape design allow for a mixed grouping of plants with varied seasonal interest. Pay close attention to the expected size of the plants.
Renovation of an Existing Landscape for Improved Water Conservation
A typical landscape can be renovated for water conservation. The prerenovation landscape (Figure 7a) has foundation shrubs surrounding the house, a hedge along three sides, and some native trees around the rear of the property.
The redesign of the residence (Figure 7b) 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 makes a natural, mulched play area. Note how the wateruse zones changed during the redesign of the property and how the amount of turf area was reduced.
An economic comparison of the landscape shown in Figure 7 (before and after renovation) was made (Tables 1 and 2). Changes in water-use zones are expected to save over 29,000 gallons of water a year. This amounts to an annual savings of $67.00 on water, $46.00 on sewage, and $237.00 on landscape maintenance. Although the do-it-yourself landscape renovation cost $1,245.00 in plants and supplies, the annual savings brought a total return on investment within three years. A water-wise landscape not only saves water . . . it saves money!
The alteration of an existing landscape to conserve water does not have to be as elaborate as the one 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 from converting irrigated turf areas to ground covers or natural mulch areas. Often large amounts of water can be saved simply by changing management practices and watering habits without making any physical changes in the landscape. For each 1,000 square feet of landscaped area converted from an irrigated to a nonirrigated area, it is estimated that you can save at least $60.00 per year on annual water and sewage costs.
Before After Savings Water use (gal.) 81,437 51,723 29,714 Water cost $200.00 $133.00 $67.00 Sewage cost $141.00 $95.00 $46.00 Maintenance costs $660.00 $423.00 $237.00 Overall cost $1,001.00 $651.00 $350.00
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