In Extreme Hot Weather, When and How Often Should You Water Your Lawn?

Dormancy Option

• Although you may worry about the state of your grass in hot weather, you can choose not to water it and allow the grass to go dormant. Although grass may appear brown and dead during dormancy, its roots are still alive. Warm-season grasses survive heat more easily than cool-season grasses, but even cool-season grasses tolerate four to six weeks of hot weather without water. If you allow your grass to go dormant, stick to your decision not to water rather than watering occasionally because inconsistent watering is hard on grass. After six weeks, give dormant grass 1 to 1 1/2 inches of water once per week and its green color will begin to return.

Timing

• It is best to water your lawn between 5 and 9 a.m.. If you water during the heat of the afternoon, water evaporation will cause your lawn to receive less moisture. If you water in the evening, water may stay on the grass overnight and make it more susceptible than normal to diseases.

Frequency

• Rather than making a schedule in which you water the lawn every several days, observe the grass for signs that it needs water. One indication is wilt, when footprints and mower marks are still visible 30 minutes after the lawn has been walked on or mowed. Another indication is that the grass turns bluish gray. Water the lawn if you notice either sign, and wait to water the grass again until you notice wilt's symptom.

Amount

• Although water the lawn frequently for short periods in hot weather may be tempting, it will diminish the grass' lushness and weaken its roots, preventing the grass from surviving drought conditions. Instead, give cool-season grasses 1 to 1 1/2 inches of water each week in a long watering session. Warm-season grasses need only 70 to 80 percent of that water amount. In order to get a sense of how long to water, place three or four baking pans at various points in your yard during watering. After 30 minutes, measure how many inches of water accumulated in the pans. Multiply the pans' average depth by two, and the result is the number of inches of water the grass receives per hour. That method makes it simple to determine how long it takes your sprinkler system to apply 1 inch of water.

Considerations

• If your yard has clay soil, then water may accumulate easily on the grass rather than be absorbed into the soil. In that case, water for a shorter period of time, wait until the water has been absorbed and then water again until reach the proper amount of water.

  If you are less concerned about keeping your grass green and more concerned with simply keeping it alive during a drought, then apply as little as 1/4 to 1/2 inch of water every two to four weeks to keep the grass roots alive. During that time, however, keep foot traffic off the lawn.