The obvious answer to drought stress on lawns is to apply water. Deep, infrequent watering to the depth of the root system is the ideal situation. This should be done when lawns show the first signs of drought stress, such as wilting, darkening color, and footprints remaining after walking across the lawn. A variety of factors, including budgets, site factors, and watering restrictions all might make this impossible. When an organic lawn care program is in place, the organic matter used to topdress the soil and the resulting improved soil structure will likely extend the greening period farther into the summer before the lawn goes dormant. This improved soil structure will also allow the grass plant to take full advantage of the moisture present and food uptake into the grass plant. Good soil structure will allow the lawn to return to active growth and recover quickly.
Dormancy is an effective drought defense for our cool-season lawns. Once cool-season turfgrasses have gone dormant (stopped active growth, turned off-color) it's best to leave them in that condition rather than watering heavily to cause the grass to green-up again. Breaking dormancy actually drains reserves within the plant, and if conditions remain dry and the weather is hot, the plant is not likely to replace those reserves. In a 'typical' summer, lawns go dormant and resume active growth when conditions improve. The downside of dormancy is the appearance of the lawn and the risk of problems arising on the inactive lawn, such as weed invasions.