Bermuda grass is a popular warm-season turfgrass across the southern United States known for its durability and resilience. Understanding its growth cycle is fundamental for proper lawn care and maintenance planning. The timing of this spring reawakening dictates when to apply pre-emergent herbicides and begin the season’s fertilization program. Since Bermuda grass thrives in high temperatures, its growth is entirely dependent on environmental signals that confirm the end of the cold season has truly arrived.
The Role of Dormancy and Spring Transition
During the colder months, Bermuda grass enters a state known as dormancy, a physiological shutdown that allows the plant to survive freezing conditions. This process is triggered when soil temperatures drop consistently below 55°F, causing the turf to cease active growth and lose its green color. The visual change to a tan or straw-like brown is a natural result of the plant degrading its chlorophyll, the pigment necessary for photosynthesis.
While the visible leaf tissue is no longer active, the plant is not dead; it is simply conserving resources. Energy reserves, primarily carbohydrates, are stored below the soil surface in the plant’s underground stems (rhizomes) and above-ground runners (stolons). This energy storage is the fuel source the grass relies on to initiate the rapid growth and “green-up” process once favorable conditions return. The success of the spring transition is directly linked to the health and energy stored in these protected underground structures.
Critical Temperature Thresholds for Activation
The mechanism that triggers Bermuda grass to exit dormancy and resume active growth is directly tied to sustained soil warmth rather than brief, warm air temperatures. For the plant to begin greening up, the soil temperature, measured at a four-inch depth, must consistently reach and remain at or above 60°F. The threshold for robust, sustained growth initiation is even higher, typically requiring the soil to be around 65°F.
This temperature requirement explains why a few sunny days in late winter are often insufficient to prompt a full green-up; the air may be warm, but the soil deep beneath the surface still retains the winter chill. The most reliable signal for the turf to fully transition out of dormancy requires both the soil temperature to be around 65°F and the nighttime air temperatures to remain above 60°F for several consecutive days. When these conditions are met, the stored energy is mobilized, and new green shoots emerge from the rhizomes and stolons, signaling the start of the growing season.
How Geography Affects Spring Green-Up
The timing of the spring green-up for Bermuda grass is highly variable and is dictated by the regional climate and how quickly the soil warms to the necessary 65°F threshold. In the Deep South, where winter conditions are milder, this critical soil temperature is often reached earlier in the year. Lawns in this region may begin to show signs of greening as early as late March or the beginning of April.
Moving north into the Transition Zone, which experiences more pronounced winter cold, the process is significantly delayed. In these areas, soil temperatures may not consistently reach the 65°F mark until late April or even mid-May, pushing back the turf’s emergence from dormancy. This difference in timing requires homeowners to monitor local soil temperatures rather than relying on a fixed calendar date for maintenance practices.