Water as infrequently as possible.
Thoroughly water when you do water so moisture soaks
down to the roots. Exceptions to this general rule would
be for newly seeded lawns where the surface needs to
stay moist, newly sodded lawns that have not yet rooted
into the soil, or when summer patch disease is a problem
(see Lawn Diseases). Otherwise, avoid frequent watering
that promote shallower root systems and weeds (e.g.,
crabgrass).
Water early if possible. Given a choice,
water early in the day when lawns are normally wet from
dew. Avoid midday due to evaporation, and at night due
to potential increased chances of some diseases. The
exception to this guide is when you are in extremely hot
weather and nighttime temperatures don't go below 68
degrees. Then it is better to water in the late
afternoon or early evening, providing you don't have
watering-time restrictions. Late in the day reduces the
amount of evaporation that takes place during the very
hot day, allowing more water to reach the root zone.
Spread the water uniformly across the
lawn. Sprinklers vary in distribution patterns, and
require spray overlap for uniform coverage. Placing
coffee cans or similar straight-sided containers on the
lawn can help measure water application rates. Avoid
flooding areas, or missing other spots. On heavy clay
soils and slopes, watch for excessive runoff; it may be
necessary to apply the water in several applications to
allow for adequate penetration.
Water conservation. To help conserve
water, mow your lawn at a higher than normal height,
avoid applying an excess of nitrogen as warm weather
approaches, limit traffic over the lawn, improve turf
rooting, control thatch and soil compaction, and avoid
pesticide use on drought stressed lawns.