Lawn dormancy is a natural survival mechanism that turfgrass uses to endure periods of environmental stress, most commonly in the summer due to heat and drought. This temporary state allows the grass plant to conserve energy and moisture by shutting down active growth. While the above-ground blades turn brown and appear lifeless, the plant’s crown and root system remain alive beneath the soil surface until more favorable growing conditions return.
The Triggers and Timing of Summer Dormancy
The timing of summer dormancy depends largely on the type of grass in your lawn, which is categorized into cool-season and warm-season varieties. Cool-season grasses, including Kentucky bluegrass, fine fescue, and perennial ryegrass, are most susceptible to summer dormancy. The primary trigger for these varieties is a combination of prolonged lack of rainfall and consistently high air temperatures.
Cool-season turfgrasses enter dormancy when air temperatures remain consistently above 85°F to 90°F, especially when coupled with soil moisture depletion over three to four weeks. The plant sacrifices its green leaf tissue to protect the grass crown. This metabolic slowdown drastically reduces the plant’s water needs, helping it survive until cooler temperatures and rain return. Warm-season grasses, such as Bermuda and Zoysia, thrive in the heat and are highly resistant to summer dormancy; they typically enter dormancy in the winter when temperatures fall below 55°F.
How to Distinguish Dormant Grass from Dead Grass
A brown lawn does not automatically mean the grass is dead, but it requires testing to determine if it is dormant. The simplest method is the “tug test,” which assesses the health of the root system. Gently pull a small handful of the brown grass blades; if the grass resists and remains anchored firmly in the soil, the roots are still alive. If the grass pulls out easily, roots and all, the turf is likely dead because the root system has failed.
A second indicator is the examination of the grass crown. Dormant grass still has a viable crown that appears pale white or yellowish-cream, indicating life and the potential for new growth. A dead plant, however, will have a crown that is brown, brittle, or shriveled, showing no signs of life. The color of the blades also offers a clue: dormant grass usually turns a uniform tan or straw color across the entire lawn. Dead grass often appears in irregular, gray, or patchy sections caused by other issues like disease or grubs.
Managing the Lawn During Dormancy
Once you have confirmed that your lawn is dormant, proper management is focused on survival, not revival. The goal is to protect the living crown and roots until the weather conditions naturally shift. Minimize all activity on the lawn because foot traffic and mowing stress the vulnerable plant tissue. The pressure from walking or driving tires can easily damage or kill the grass crowns, leaving permanent tracks and bare spots.
Fertilization should be suspended entirely, as a dormant plant is not actively growing and cannot properly utilize the nutrients. Applying fertilizer without sufficient water can burn the grass and cause further damage. The most important action is providing “survival watering” to keep the crowns from completely drying out. This minimal irrigation involves applying about a half-inch of water every two to three weeks to wet the top few inches of the soil. This small amount provides enough moisture to keep the plant alive until seasonal conditions allow for a full recovery.