Watering Lawns

Though lawns do need lots of water, many gardeners are too generous, often providing twice the amount the lawn really needs. Over watering does more than just waste water. It leaches fertilizer and natural soil nutrients from the root zone; it creates perpetually wet conditions that can encourage disease. And a heavily watered lawn grows faster and requires more mowing.

In general, warm-season grasses require less moisture than cool-season types; the tall fescues are among the least needy of the cool-season sorts. On average, however, most of grasses need 1 to 2 inches of water per week (except when rainfall makes up the difference). To encourage roots to grow deep, it's best to water infrequently, adding the 1 to 2 inches all at one go. If you simply sprinkle on a little water each day, the roots will stay near the surface. If there is then a prolonged dry spell or if you forget to water, the root system won't be able to draw enough water from deeper in the soil to survive.

After watering, wait until the top inch or two of soil has dried before watering again. To check, probe the soil with a thick piece of wire or a long screwdriver: it will move easily through moist soil but stop when it reaches firmer, dry soil. You can also use a soil sampling tube. An even faster way to tell if a lawn needs watering is simply to walk across it. If your footprints remain for several minutes, it's time to water (a well-watered lawn springs right back).

Water early in the day, when there's less moisture loss due to heat evaporation and wind is less likely to blow water away. If you need to water later in the day, do so well before dusk, so the grass will dry before nightfall; grass that stays damp for long periods is typically more susceptible to disease.

Most lawns are watered by sprinklers--either the hose-end sort or those that are part of a fixed system.