Heat and moisture stresses placed on both cool-season and warm-season grasses will force them into a dormant stage. Just because they are brown does not mean they are dead. Normally, cool-season grass (tall fescue and ryegrass) will rebound in the fall when temperatures cool and rain is more abundant. Warm-season grasses will rebound in the spring after periods of adequate rainfall and when temperatures warm to optimal growing conditions. A prolonged drought period could do permanent damage to lawns without supplemental and deep watering. Watering for longer intervals, less frequently will encourage deeper root systems and be less stressful to the plant.
Dormant lawns should receive at least an inch of water every two or three weeks during the summer to prevent complete turf loss. Grasses may not show a noticeable greening, but the amount of irrigation should be sufficient to hydrate the lower plant portions and increase the recovery once adequate moisture is available.
Some species of turf possess deeper root systems which allow them greater access to soil water during drought conditions. In addition, some species require less water than others. Tall fescue has better drought tolerance than Kentucky bluegrass and generally requires little or no irrigation except during extended drought.