Water the roots
It's better for the overall health of your lawn and pocketbook to water your grass deeply and less frequently. Apply at least 2.5 cm (1 inch) of water to the area. You can measure the amount by placing a container such as a pie pan on the lawn during watering.
Grass growing near large trees may need more frequent watering, as tree roots may use much of the soil water. Watering for short periods of time and more frequently promotes shallow root growth and leaves your grass susceptible to drought conditions – and it uses more water!
Too much of a good thing
More water is not always better for your lawn. Excessive watering can lead to poor growing conditions and potential disease problems.
Water only when your lawn is showing signs of wilt. Early morning is the ideal time for watering. This minimizes water lost through evaporation and wind.
In extended dry periods, a lawn may wilt, turn brown and become dormant. A healthy lawn can survive several weeks in a dormant state and will green up again with regular moisture conditions.
Source: Lawn Maintenance brochure, Health Canada, 2002.