Bermuda grass is a warm-season turf species widely used across the southern United States, prized for its durability and resilience in high heat. This vigorous grass enters a state of dormancy during the colder months as a natural, protective survival strategy. Instead of dying, the plant temporarily halts its above-ground growth and conserves energy. This seasonal change ensures it can return to vibrant growth when warm temperatures return.
The Environmental Triggers That Cause Dormancy
The primary signal for Bermuda grass to begin its winter rest is a sustained drop in soil temperature. When soil temperatures fall consistently below about 55°F, the grass’s metabolic activity slows significantly, prompting the onset of dormancy.
A decreasing photoperiod, or the shortening of daylight hours in late autumn, also contributes to this shift. Reduced sunlight signals that the active growing season is ending and resources must be conserved. This combination of cooler temperatures and reduced light intensity triggers the plant to stop producing chlorophyll, which is responsible for its green color.
The plant’s energy is then strategically pulled back from the leaf blades and stored within protected underground structures, specifically the rhizomes and stolons. These parts hold the stored carbohydrates and nutrients necessary to fuel new growth in the spring. By pulling energy into the base, the grass protects its growing points from potential damage caused by frost and freezing temperatures.
Visual Indicators and Seasonal Timeline
The most obvious visual indicator that Bermuda grass has entered dormancy is a shift in color from green to a straw-like brown or tan. This tan appearance is not a sign of death, but the visible result of the plant ceasing growth and chlorophyll production. The entire lawn takes on this uniform, dormant color once colder conditions set in.
The seasonal timeline for this transition typically begins in the late fall or early winter, depending on the region. The grass remains in this resting phase throughout the coldest parts of the year, with top growth stopping completely. Bermuda grass exits dormancy and begins to green up again when soil temperatures consistently exceed 65°F, usually occurring in the early to late spring.
Essential Winter Management for Dormant Bermuda Grass
Mowing and Watering
Proper management during the dormant phase ensures the grass survives winter and achieves a healthy green-up in spring. The first adjustment is significantly reducing or entirely stopping mowing, since the grass is no longer actively growing. It is beneficial to set the final mowing height in the fall slightly higher than the summer height, which provides insulation to the protected crowns.
Infrequent watering is still necessary to prevent the root system from drying out completely, a condition known as desiccation. If natural rainfall is scarce, providing approximately one inch of water every four weeks is a guideline to maintain root health. Sandy soils or areas prone to high winds may require slightly more frequent, light irrigation.
Overseeding
For homeowners who want a green lawn through the winter, overseeding the dormant Bermuda grass with a cool-season variety, most commonly perennial ryegrass, is an option. This process requires careful timing in the fall when nighttime temperatures drop into the mid-50s, allowing the ryegrass to establish before the first hard frost. Overseeding, however, means sacrificing the ability to apply pre-emergent herbicides, which are typically used during this period.
Weed Control
The dormant state is an ideal time to apply pre-emergent herbicides to control the germination of winter annual weeds. These treatments create a chemical barrier in the soil that stops weed seeds from sprouting without harming the established, dormant turf. The fall application is often timed when soil temperatures drop below 70°F, targeting common winter weeds like annual bluegrass and chickweed. Applying pre-emergent herbicides during dormancy helps the Bermuda grass face less competition when it emerges in the spring.