Glen has been telling me these facts for years -- especially about how to drive the roots of the grass deeper into the ground. Now Steve sent me this clip from Scotts Canada about lawn watering. I think I am going to go out and find a rain gauge. My internet research tells me they can be purchased anywhere from $7 to $250. I am going to begin with the economy model.
Lawns need at least 2.5 cm of water per week. Use a rain gauge to measure the rainfall during the week and make up the difference with a lawn sprinkler.
Water only once or twice a week, but water deeply to reach the roots. Frequent watering only wets the lawn’s surface and forces the roots to remain shallow. Deeper root systems help lawns survive stressful periods of heat and drought. Early in the morning is the ideal time to water for most lawns. There’s less wind, less hot sun, and your lawn has a full day to dry. Watering at night invites mildew and fungus.