When a lawn loses its vibrant green color and turns straw-like brown, it has entered dormancy. Grass dormancy is a natural survival strategy where the plant intentionally slows or halts its growth and sacrifices its green leaf tissue to conserve energy and moisture. The plant redirects resources to protect the crown and root system, which are necessary for its eventual recovery. This temporary shutdown allows the turf to survive environmental stress that would otherwise cause permanent damage.
Seasonal Timing Based on Grass Type
The time a lawn goes dormant depends entirely on whether the grass is a cool-season or a warm-season variety. These two categories of turfgrass thrive during different temperature ranges, causing their active growth and dormant periods to occur in opposite seasons. Understanding your grass type is the first step in knowing when to expect the color change.
Cool-season grasses, which include varieties like Fescue and Kentucky Bluegrass, grow vigorously during the cooler temperatures of spring and fall. They enter dormancy during the high heat and drought of mid-summer, typically between July and August. They slow growth when soil temperatures rise, effectively taking a summer break to survive the heat.
Warm-season grasses, such as Bermuda and Zoysia, operate on the reverse schedule, performing best during the hottest months. Their dormancy is triggered by cold weather and occurs during late fall and winter, often beginning around November and lasting until March. When the first consistent frost arrives, these grasses lose their green pigment and turn a uniform tan color, remaining inactive until the soil warms up in the spring.
Environmental Conditions That Trigger Dormancy
While the calendar season provides a general timeframe, dormancy is ultimately triggered by specific environmental stresses. The most common trigger is a lack of moisture, where prolonged drought conditions force the plant to prioritize its root system over leaf growth. When the grass cannot take up enough water to sustain transpiration and photosynthesis, it shuts down its metabolism and turns brown to reduce water loss.
Temperature extremes also act as a switch for dormancy. Cool-season grasses enter heat-induced dormancy when air temperatures consistently exceed 85 degrees Fahrenheit, especially if coupled with dry soil. They can also enter a cold-induced dormancy if temperatures consistently drop below 56 degrees Fahrenheit, though this is less common than summer dormancy.
Warm-season grasses are driven into dormancy by the cold. Their growth significantly slows when temperatures fall below 74 degrees Fahrenheit and they enter full dormancy when temperatures remain consistently below 55 degrees Fahrenheit. The plant stops producing chlorophyll and uses stored energy reserves to protect its underground crown and rhizomes from freezing damage.
Identifying Whether Grass Is Dormant or Dead
A uniform, straw-brown lawn can be alarming, but distinguishing between dormant and dead grass is a simple process. Dormant grass exhibits a tan or light brown color across the entire lawn, maintaining a uniform appearance. Dead grass, however, often appears as irregular, gray, or brittle patches, indicating a localized problem like disease, insects, or chemical burn.
One reliable method is the “tug test,” which assesses the strength of the root system. Gently pull on a few blades of the brown grass; if the plant resists and stays firmly rooted, it is merely dormant, meaning the roots are still alive. If the grass pulls up easily with no resistance, almost like pulling a handful of loose hay, the plant has died.
A final check involves examining the crown, the base of the grass plant where the blades meet the roots. Carefully dig up a small section of turf and peel back the outer dead leaf layers. A healthy, dormant crown should be white, yellowish, or creamy and soft to the touch, indicating living tissue. If the crown is completely brown, shriveled, and crumbly, the grass is dead and cannot recover.
Lawn Care During the Dormant State
Maintenance practices must change drastically when turf enters dormancy to avoid causing harm to the fragile, resting plant. The most crucial adjustment is to minimize foot and vehicle traffic. Dormant grass blades and crowns are highly susceptible to physical injury, and heavy traffic can easily crush the living crown, creating permanent bare spots that will not recover until the grass is actively growing.
Watering should be minimal and focused only on survival, not on trying to force the grass to turn green. If dormancy is drought-induced, providing a light application of a half-inch of water every two to three weeks is sufficient to keep the crown hydrated and alive. Applying excessive water can deplete the plant’s stored energy reserves by encouraging a premature re-greening, which can be fatal if heat and drought stress immediately return.
Mowing should be suspended entirely while the grass is dormant because cutting the blades further stresses the plant. If the grass has been dormant for a prolonged period and some growth is visible, raise the mower deck to its highest setting. Avoid applying fertilizer during this period, as the dormant plant cannot absorb the nutrients and the fertilizer may promote weed growth or burn the turf.