Is it necessary to water an established lawn during hot, dry weather?

FAQ
Question: 

Is it necessary to water an established lawn during hot, dry weather?

Answer: 

Gardeners have two basic options when confronted with hot, dry weather.  One option is to do nothing and allow the grass to go dormant.  The alternative is to water the turfgrass during dry weather to maintain a green, actively growing lawn. 

Cool-season grasses, such as Kentucky bluegrass, can survive long periods of dry weather.  In dry weather, the shoots of the turfgrass plants stop growing and the plants go dormant.  Dormancy is a natural survival mechanism for turfgrass.  While the leaves have turned brown and died, the turfgrass roots and crowns remain alive.  Generally, Kentucky bluegrass can remain dormant for 4 to 6 weeks without suffering significant damage. 

Cool-season grasses are at risk of dying if dormant for more than 6 weeks.  To insure survival of dormant grass, it’s best to water lawns that have been dormant for 6 weeks.  Apply 1 to 1½ inches of water in a single application.  Water again 7 days later.  The grass should begin to green up after the second application.