Xeriscape Gardening

The word "Xeriscape," was coined by the Denver Water Department in 1981 to help make water conserving landscaping an easily recognized concept. The word is a combination of "landscape" and the Greek word "xeros," which means "dry."

According to the Denver Water Department's web site, xeriscape is a method of landscaping that promotes water conservation. Rather than a specific "look" or a limited group of plants, Xeriscape is a combination of seven basic landscaping principles. These principles are explained below in the order a landscape planner or property owner would consider to install the best landscape. Each principle must be considered during the planning and design phase, but the sequence of installation is also very important in assuring a successful Xeriscape.

The seven principles of Xeriscape are:

1. Planning and Design
Trying to create a landscape without a plan is like trying to build a home without blueprints. A plan provides direction and guidance and will ensure that water-conserving techniques are coordinated and implemented in the landscape.

The first step is to look at your existing landscape and create a "base plan." This is a to-scale diagram showing the major elements of your landscape - your house, driveway, sidewalk, deck or patio, existing trees, etc.

To measure your landscape, you'll need a 50 foot or longer tape measure, and a helpful relative/friend. You will need to measure from the property lines to your house, as well as all the exterior walls of your house. You will also need to measure other impervious surfaces, such as sidewalks, decks and driveways. If there are existing trees, shrubs, etc. that you wish to keep, you'll need to measure to place them accurately in your plan. Once you've recorded all the measurements, you'll have to transfer them to graph paper. Most designers prefer to work with plans drawn to a 1:10 or 1:8 scale. This means that every 10 (or 8) feet of actual measure equals 1 inch on your plan. So if your property is 50 feet wide by 100 feet long and you're using a 1:10 scale, your plan would be 5 inches by 10 inches.

Once you've drawn your property lines on the graph paper, you need to fill in the details, including the house outline, sidewalks, driveways, etc. You also need to show direction on your plan by drawing an arrow indicating North. This will help your designer select plants appropriate for specific exposures. Some of the other things you should include on your base plan are:

  • the location of spigots, downspouts and external electrical outlets.
  • fences, walls and other structures
  • existing lawn, garden, shrub masses and flower beds \
  • trees (both yours and your neighbors, if they shade part of your yard)
  • slopes

Once you've completed a base plan of your existing landscape, you need to think about how you want to use your new Xeriscape. Examples of uses can include a place to let the dog romp; an inviting approach to your front entrance; the selection of a tree to block an unsightly view; the placement of a vegetable garden and so on.

The final step is to develop a "planting plan," indicating what types of plants should go where in your yard.

2. Soil Improvements
Front Range soils tend to fall into one of two categories: sand and clay. Clay soil is dense, slow to absorb and release water. If water is applied to clay soil too quickly, it either pools on the surface or runs off. Over watering heavy clay soil can actually drown plants.
On the other hand, sandy soil can't hold water. Unless irrigated frequently, plants in sandy soils tend to dry out.

To enable your soil to better absorb water and allow for deeper roots, you may need to add a soil amendment before you plant. For most soils, adding 1 to 2 inches of organic matter such as compost or well-aged manure to your soil can be beneficial. Rototill the organic matter into the soil at least 6 inches deep.

(Note: if you are landscaping with native plants, soil amendments may not be necessary, as they prefer soil that is not too rich. For many of these plants, the only soil preparation necessary is to loosen the soil.)

3. Efficient Irrigation
A Xeriscape can be irrigated efficiently by hand or with an automatic sprinkler system. If you're installing a sprinkler system, it's a good idea to plan this at the same time you design the landscape. Zone turf areas separately from other plantings and use the irrigation method that waters the plants in each area most efficiently. For grass, low-pressure, low-angle sprinklers irrigate best. Drip, spray or bubbler emitters are most efficient for watering trees, shrubs, flowers and groundcovers.

If you water by hand, try to avoid oscillating sprinklers and other sprinklers that throw water high in the air or put out a fine mist. The most efficient sprinklers put out big drops and keep them close to the ground. Water deeply and infrequently to develop deep roots. The best time to water is between 9 p.m. and 9 a.m. to reduce water loss due to evaporation. If you have an automatic sprinkling system, adjust your controller regularly to meet seasonal needs and weather conditions. Also, install a rain shut off device.

4. Zoning of Plants
Different areas in your yard get different amounts of light, wind and moisture. To minimize water waste, group together plants with similar light and water requirements, and place them in an area in your yard which matches these requirements. A good rule of thumb is to put high water-use plantings in low lying drainage areas, near downspouts, or in the shade of other plants. It's also helpful to put higher water-use plants where it is easy to water.

Dry, sunny areas or areas far from a hose are great places for the many low water-use plants that grow well in our climate. Planting a variety of plants with different heights, color and textures creates interest and beauty. By grouping your plants appropriately, you minimize water waste while ensuring that your plants will flourish in the right environment.

5. Mulches
Mulching is essential for gardening along the Front Range. Mulch helps keep plants roots cool, prevents soil from crusting, minimizes evaporation and reduces weed growth. Mulches also give beds a finished look and increase the visual appeal of your garden.

Organic mulches, such as bark chips, pole peelings or wood grindings, should be applied at least 4 inches deep. Because they decompose over time, they're an excellent choice for new beds. As plants mature and spread, they'll cover the mulched areas.

Inorganic mulches include rocks and gravel, and should be applied at least 2 inches deep. They rarely need replacement and are good in windy spots. However, they should not be placed next to the house on the sunny south or west sides, because they tend to retain and radiate heat. Mulch may be applied directly to the soil surface or placed over a landscape fabric. (Note: Do not use black plastic because it prevents air and water from reaching to the plant roots.)

6. Turf Alternatives
Traditionally, the landscape of choice along the Front Range has been a carpet of bluegrass turf. Bluegrass is lush and hardy, but in our semi-arid climate it requires a substantial amount of supplemental watering.

One way to reduce watering requirements is to reduce the amount of bluegrass turf in your landscape. Native or low water use plantings, patios, decks or mulches can beautify your landscape while saving water. Choosing a lower water using turf also serves the same purpose. Such choices can include buffalograss, blue grama grass, turf type tall fescue and fine fescues.

7. Appropriate Maintenance
Preserve the beauty of your Xeriscape with regular maintenance. The first year or two, your new landscape will probably require a fair amount of weeding, but as plants mature they will crowd out the weeds, significantly reducing your maintenance time.

In addition to weeding, your Xeriscape will need proper irrigation, pruning, fertilizing and pest control. Maintenance time for a new garden is similar to a traditional landscape, but it decreases over time. In addition to weeding, proper irrigation, pruning, fertilizing and pest control will keep your landscape beautiful and water thrifty.

For more information, visit Denver Water's Xeriscape demonstration garden at its Administration Building, 1600 West 12th Avenue, Denver, and its web site at www.water.denver.co.gov.