By Sharon Omahen
University of Georgia

Recent Georgia rains have cut down on one landscaping chore: irrigating the lawn. But when it's time to turn on your system again, experts urge you to use it wisely.

"Irrigation supplements rainfall, and most years in Georgia, even in summer, it isn't needed every day," said Rose Mary Seymour, an Extension Service water specialist with the University of Georgia College of Agricultural and Environmental Sciences.

Too much, too often

Seymour said homeowners with irrigation systems often water too much and hurt their plants and grasses.

"Plants that are stressed by excess water are more susceptible to disease and pest infestations," she said. "When used wisely, a home irrigation system can be a useful landscape tool."

If your system is automated, it should have either a timer or a controller.

"To efficiently irrigate, you need to know how to adjust, reset and program your system's controller," Seymour said. "The controller is a combination of a clock and calendar and instructions that you provide. Together, these components turn valves on and off in your irrigation system."

To set the system, check the instruction manual for your controller and a controller chart, a drawing of your landscape showing areas covered by each irrigation zone. Each zone is controlled by the corresponding station number.

Consult your manual

The manual explains the options for managing the system.

What if you can't find your instruction manual?

"Any manufacturer or their local distributor can supply a set of instructions," Seymour said. "Just call and request a copy."

Be sure to have your system's model number and name handy. Another easy way to get a manual is to visit the manufacturer's Web site. Most firms offer their newer instruction manuals on the Web.

If you don't have a controller chart, you can make one, Seymour said. Just sketch the landscape and the irrigated area.

Set the controller to run each station and draw an outline on your landscape sketch of the areas each station irrigates. Then label each station with the appropriate controller number on the drawing.

"It's also good to note what types of plants are in each zone," she said, "so you can adjust each station's run time for the plants' needs."

Rain sensors worth extra cost

If your system doesn't have a rain sensor, add one.

"A rain sensor detects rainfall and prevents the system from irrigating when it's raining," Seymour said. "This is add-on equipment, but they're inexpensive and usually pay for themselves in water savings in one or two years."

You can buy a rain sensor and install it yourself or have an irrigation contractor put it in. Either way, put it where it's not covered by building eaves and doesn't collect irrigation water. It may be best to attach it to the roof edge where there are no interfering trees.

Rain sensors are mandatory on any automated system installed in 16 counties around Atlanta after Jan. 1, 2005. "Even if it's not mandatory in your area," Seymour said, "it's the easiest way to reduce water waste from automated irrigation systems."

Whether you use an automated or manual system or just water with a garden hose, follow your county's or city's watering schedule.

"Be aware of the current outdoor watering restrictions in your community and use them as a guide," Seymour said. "But don't just water because it's your day to water. Water based on your plants' needs."

Turf grass needs water just as it begins to wilt. Signs include a change to a dull, grayish or bluish green and leaves that begin to fold.

Annual flowers have shallow root zones, so they usually need to be watered more often than perennial flowers, which have deeper roots.

Trees and shrubs have even deeper, more extensive roots. They can get to water far underground. Most can survive a long time without rainfall.