Water-Conserving Landscaping Involves More Than Plant Selection

6/20/2001   BOZEMAN -- Drought is just an exaggeration of what Montanans see most years -- dry conditions.

            But every time we have a severe drought, "people become more interested in alternatives to a turfgrass yard, since turfgrass is the most water-intensive landscape you can have," says Dick Pohl, Montana State University's landscape architect. Pohl teaches in MSU's Plant Sciences and Plant Pathology Department as well as designing campus landscapes. He has had an interest in native plants and designing drought-tolerant landscaping for many years.

           Drought-tolerant landscape design is more formally called "xeriscaping," from the word "xeric" that means adapted to an extremely dry habitat. Such landscaping can dramatically cut water use in a yard, but many people focus only on selecting drought-tolerant plants.

            "You can accomplish more in terms of reducing water usage if you start a bit more broadly," says Pohl.

            Part of that beginning is making sure that you make available the water that flows nearby, including catching available rain runoff, terracing or grading to reduce runoff and adding organic matter to the soil so it can hold more water. As you select sites for plants, consider how the slope of your land will channel water to your moisture-loving plants. At MSU, sections Pohl has designed include areas fed by water running from parking lots. A home approach could use the water dispersed from down-spouts or funneled from a walkway. It doesn't take a ditch to funnel water. A slight lowering of the ground compared to the surrounding area is enough to give run-off a specific direction.

            "Adding organic matter is one of the most frequently missed options, and it's very important," says Pohl. Soil with higher organic matter holds more water. Both sand and clay soils have little organic matter. A good organic soil is so important for efficient water storage that people building a new home on a site with poor soil should consider amending the soil with compost or other organic matter at the outset. It's a lot easier for the builder or landscaper to plow organic matter into the soil than it will be for you to take a shovel or tiller to it later.

            Whatever your soil is like, make sure you use the organic matter you grow. A mulching mower and organic fertilizers can help. Watering properly to degrade the mulch and feed a healthy organic cycle is another necessary step.

            In selecting plants, remember that low-mowed turf grass requires more water than any other landscape, says Pohl. But selecting plants isn't a simple or isolated part of the process.

            "When people decide to change some of their landscape from turf grass, often they think that simply selecting plants labeled 'native' to Montana is all they have to do. But we have water-loving plants in Montana, too. You need to look at what kind of environment the plant comes from before making a choice."

            If you decide to use some plants with low water needs and others with greater water needs, group them accordingly: dry tolerant plants together and water loving plants together, watering each section according to its needs.

            Also consider how shade minimizes evaporation, says Pohl.

            Just as plants shaded by a large tree may require less water, so taller grasses shade the ground more than shorter grasses. Setting your mower to a higher cutting length can help grass use less water.

            Planting some areas in bunch grasses and letting them grow without mowing can add a variety of textures and colors to the yard while minimizing water use. Among the warm season bunch grasses native to Montana are buffalograss, blue grama grass and sheep fescue.

            For flower, vegetable and shrubbery beds, be sure to mulch heavily to reduce water loss through evaporation.

            When you do water, use the more efficient low-volume watering devices, like soakers and drip irrigation systems.

            "Propelling water up into the air wastes about 75 percent of it, depending on how windy it is," says Pohl.

            In landscaping to conserve water, people should also consider some non-native species.

            "There are many non-native plants that are very desirable for use in low water consuming landscapes," says Pohl. "Plants such as Russian olive, sea-buckthorn and several species of juniper that come to us from Asia are not only very drought tolerant but are also salt tolerant where problem soils may create difficult growing conditions. Natives help to perpetuate the local conditions, but new introductions from other parts of the world can claim an important role in conserving water."

            Following is a list of less common native plants. For a list of some of the more common options, you may want to order MSU Extension Bulletin 323 "Trees and Shrubs in Montana," a $4 publication that lists many common trees and shrubs. To order the Extension bulletin, contact your local county Extension Service office or MSU Extension Publications, PO Box 172040, Bozeman, MT 59717; credit card orders phone (406) 994-3273. In some cases, companies that specialize in agricultural crop seeds also have access to native species that are commonly used to revegetate disturbed landscapes like roadside and power-line corridors. Some free gardening publications are on the web at: http://www.montana.edu/wwwpb/pubs/hort.html

  White spirea, seen above right, is a dry-loving native Montana shrub that grows to about three-foot tall.

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Send questions or comments to Carol Flaherty, MSU Communications Services, Bozeman, MT 59717 or email Flaherty at carolf@montana.edu.

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