When temperatures fall consistently below a certain point, the grass does not perish; instead, it initiates a natural, protective process called winter dormancy. This state is the plant’s survival mechanism, allowing it to conserve energy and resources until favorable growing conditions return. The visual change from vibrant green to a straw-brown color is a normal and expected part of its yearly cycle.
Understanding Bermuda Grass Dormancy
The shift into dormancy is primarily triggered by cooling soil temperatures and shorter daylight hours in the late fall. Bermuda grass growth slows dramatically once soil temperatures drop below 60°F, eventually stopping active growth when temperatures consistently fall into the 50–55°F range. This temperature threshold signals the plant to prepare for the cold season by stopping the production of chlorophyll, the green pigment responsible for photosynthesis.
The loss of chlorophyll is what causes the grass blades to turn tan or brown. During this phase, the plant systematically redirects its stored carbohydrates and energy reserves to its protected, underground structures, specifically the rhizomes and stolons. These robust, horizontal stems remain alive and insulated beneath the soil surface, ensuring the plant’s core survival throughout the winter.
Fall Preparation for Winter Survival
Proactive measures in the late fall are essential for strengthening the grass before it enters its dormant state. Final fertilization should be designed to enhance cold tolerance and root hardiness. This application should feature a high ratio of potassium (the third number in the NPK fertilizer analysis) while significantly reducing nitrogen input.
Potassium helps condition the plant’s cell walls to withstand cold stress and aids in water regulation. An ideal winterizer blend might have an NPK ratio, such as 5-10-30 or a similar high-potassium formula, applied roughly four to six weeks before the first expected hard frost. Applying a high-nitrogen fertilizer late in the season is discouraged because it can stimulate tender new growth susceptible to freeze damage.
Mowing adjustments are also necessary to prepare the turf for dormancy and reduce the risk of winter diseases. Gradually lowering the cutting height to about 1 to 1.5 inches helps remove excess leaf tissue that could otherwise mat down and promote fungal issues like snow mold. Although the grass requires less moisture during this time, a final, deep watering before the ground freezes solid helps hydrate the root zone and prevent desiccation throughout the winter.
The Spring Awakening Process
The transition out of dormancy begins when the soil warms up again in the spring, signaling the rhizomes to send up new shoots. Bermuda grass actively resumes growth and begins to “green up” when soil temperatures at the four-inch depth consistently reach 65°F. This usually correlates with consistent daytime air temperatures climbing into the 70s.
A key practice at this time is spring scalping, which involves mowing the turf at the lowest setting, typically down to three-quarters to one inch, to remove the layer of dead, brown winter growth. This action allows sunlight to penetrate the soil, accelerating the warming process and encouraging faster green-up. It is important to bag and remove these clippings to prevent a thick thatch layer from accumulating.
The first application of nitrogen fertilizer should be timed to coincide with the start of active new growth to fuel its vigorous spring expansion. If brown patches persist, gently tug on the runners: firm, white underground rhizomes mean the plant is struggling but alive, while shriveled, dry runners indicate winter stress. Addressing bare spots early with patching or overseeding ensures a thick lawn for the coming season.