The water use rates of cool season turfgrasses during the summer period will often exceed the rate which natural rainfall returns water back into the soil. Once the soil moisture reserves are nearly depleted, the turfgrass will begin to wilt. Wilt is a sign of water stress and is usually most evident during mid to late afternoon periods. A period of continual water stress that limits or prevents the growth of plants is termed drought. Once drought conditions develop, the lawn will stop all growth and development and proceed into dormancy.
Dormancy is characterized by the development of brown turfgrass.
The turfgrass is not dead but instead in a condition to preserve the vital parts of the plant. By becoming dormant, turfgrasses reduce water usage and can concentrate the limited amount of available moisture into the crown, rhizomes and roots. This dormant condition will allow the turfgrass plant to survive adverse conditions for extended periods until soil moisture reserves are replenished. The length of time lawn grasses can survive in a dormant condition is contingent on a number of factors including soil moisture levels, daytime temperatures, condition of the turfgrass at the onset of dormancy, etc. In general, turfgrasses can be expected to survive in a dormant condition for up to 4 to 5 weeks with limited damage if temperatures are at or below normal.