Montana State University

Northern Gardening Tips: Water conservation in the landscape

June 15, 2007 -- By Cheryl Moore-Gough MSU Extension Horticulturist

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Water conservation is always important, even with much of the state receiving good rainfall this spring. After years of drought, it will take more than one wet spring to fill the soil. This column is one of two that will deal with water conservation.

Having a nicely landscaped yard while conserving water is more than choosing drought tolerant plant species, although that helps too. Xeriscaping, which is a term trademarked by Denver Water, is the wise use of water through water-efficient landscaping. Its principles are based on common sense and thoughtful planning. The word comes from the Greek Xeros, which means 'dry,' which certainly fits much of Montana most of the time.

To start developing a xeriscape or water-efficient landscape, you need to design and organize it with irrigation in mind. Many folks think irrigation means a high pressure sprinkler system, but while that may be the ticket for high water use areas like lawns, that's not always the best way to water. Drip irrigation, soaker hoses and bubblers use much less water and may be used to irrigate individual plants, avoiding watering the areas between the plants.

A water-efficient landscape groups plants together based on their watering needs. Plants with moderate watering needs, such as those needing water once per week, should be planted together and watered using drip or trickle systems. Plants with low watering needs, such as those needing only an occasional shot with a hose, also should be grouped together.

Using more water than your plants need is not only wasteful, with excess running over hot cement or onto nearby weeds, but isn't best for the plants. High pressure water often results in runoff and wasted water. A slow, gentle stream will soak in more deeply than a hard, fast shot. Low pressure sprinkler systems like drip emitters, bubblers and soakers deliver small amounts of water exactly where needed.

Whether xeriscaping or maintaining a traditional landscape, pay attention to the time of day and the weather when you water. It's most efficient to water in the early morning when temperatures are rising. The roots will stay moist and leaf blades will dry more quickly than when watered in the night, reducing your chance of disease. Modify your watering practices according to plants' needs, season and the weather. If you have an automatic lawn watering system, consider installing a rain sensor that will turn your system off in the rain. And speaking of rain, collect or channel rainwater for use in the garden. That water is free! Avoid watering during hot, windy periods, particularly with sprinklers that throw fine mist into the air. Much of that water never reaches your plants due to rapid evaporation.

Low-mowed Kentucky bluegrass lawns require more water than any other plant in your landscape. If you set your mower higher, the grass uses less water. In addition, the roots will grow more deeply in response to the additional blade growth, and the blades of grass will transpire water into the air more slowly.

Another xeriscaping possibility is to reduce the area of turf grass in your landscape. If you remove the sod, incorporate organic matter into the top six inches of soil, and cover the area with a landscape cloth and mulch, you have an attractive start to a perennial bed that you can water with drip irrigation. (I'll have more about mulches in the column after this one.)

Often overlooked as a potential xeriscaping tool is a flagstone pathway. Such paths are an attractive addition to yards, giving a nice walkway and also leading the eye to a focal point further into the garden, such as a nice specimen tree or bush. You can use creeping thyme to fill in between flagstones. There are several different species of thyme, so be careful when you purchase your plants. Common or garden thyme (Thymus vulgaris) would not be a good choice between flagstones, but woolly thyme, (Thymus pseudolanuginosus) or mother of thyme (Thymus serpyllum) would.

I've also seen some yards where folks have converted almost an entire small yard into a series of multi-level entertainment decks, complete with beautiful potted plants, table and barbeque, eliminating the mowing and watering of grass completely. Now THAT's livin!

Next time: The use of mulches and wise choices for plant materials.

: Cheryl Moore-Gough (406) 994-6523 or hort@montana.edu