Lawns need water not only during the hot, dry summer, but also in the spring and fall. When your grass begins to wilt, water thoroughly with one inch of water. This deep watering encourages grass roots to grow straight down, making your lawn less susceptible to disease and heat stress.

Here's an easy way to measure how much water your lawn is getting: set empty coffee cans on the grass where they can catch water from your sprinkler. Check them periodically, and when one inch of water has collected, turn off the sprinkler. Make a note of how long it took for that one inch to accumulate and remember it for next time.

The best time of day to water is in the early morning when evaporation rates are low and grass can dry completely. If you water in the evenings, the grass doesn't have enough time to dry, and excess moisture makes the lawn susceptible to disease.