With recent temperatures topping 100 degrees, non-irrigated turfgrasses are showing signs of heat and drought stress. The initial visual symptom looks like dark spots in the lawn. This is due to leaf curling. The symptoms are most pronounced during the heat of the day. Often the plant will re-hydrate overnight. At some point, if the turfgrass plant is not able to re-hydrate, the leaves will turn brown and result in thinning of the turfgrass. But, just because the turf turns brown does not mean it is dead. This is the plant’s protection mechanism.
It does not matter if the grass is tall fescue or zoysiagrass, the response is very similar. If allowed to go into summer dormancy, tall fescue can survive for an extended period of time despite its brown appearance. In one experiment conducted during last summer’s intense heat and drought, all of our tall fescue cultivars tested recovered after 40 days without any water and most survived 48 days without water. The grasses then grew back from their crown when watering resumed. This is why we suggest dormant lawns are watered every three to four weeks with about ½ inch of water to keep the turf crowns hydration.