Lawns should be watered as they need it, but how can you tell? You can tell at a glance if you know the signs.
As a lawn dries out, the foliage wilts--the blades of grass curl or fold. When this happens, there will be a subtle color change from rich green to a dull blue-green. A second clue is loss of "bounce." Walk across the lawn in the morning. If your footprints remain for more than a few seconds, the lawn isn't springing back and it's time for watering.
When you do water, water long enough to allow the water to soak in below the root zone. Shallow watering encourages shallow root growth, which means it will be subject to drought damage and require ever more frequent waterings. Shallow watering also allows weeds to establish at the surface.
It will take about an inch of water to penetrate 6 to 8 inches into the soil. Set out shallow cans in the sprinkler area to measure.
The best time to water is early in the morning. There is usually less wind, temperatures are moderate, and there is less chance for diseases to get established.
Watering in the afternoon is the worst from the point of view of water conservation. Up to half the water can evaporate in the air or on the ground during the hot part of the day.
Where there are water shortages, night watering and other restrictions often control the schedule. In these areas, do not apply nitrogen fertilizer, keep the grass taller than normal, and if you do get a shower, think about watering during the rain to reduce evaporation and penetrate 6 to 8 inches into the soil. Most passing showers do not provide the full inch of rain needed for deep watering.
You can improve your lawn's efficiency by removing thatch and aerating your lawn. Compacted soil and thatch prevent water penetration.
Soils rich in decomposed organic materials will do a better job of holding moisture. You can add it from the top down by spreading a 1/2-inch layer of peat moss on the lawn and working it down into the root area with a rake.
Photography by Sabin Gratz/National Gardening Association.