The appearance of a large, brown lawn during winter can be alarming for any homeowner, suggesting the grass has died. This widespread color change is a natural survival mechanism for certain types of turf. The presence of a straw-colored, dormant lawn is not a sign of death but rather an indication of the specific grass variety planted. This seasonal transformation depends entirely on the species of grass and its biological response to colder temperatures.
The Difference Between Warm-Season and Cool-Season Grasses
The primary factor determining a lawn’s winter color is its classification as either a warm-season or a cool-season grass. These two categories are defined by the temperature ranges in which they achieve their best growth. Warm-season grasses thrive in temperatures generally between 80°F and 95°F, making them suited for warmer climates like the Southern United States.
Cool-season grasses prefer milder conditions, with optimal growth occurring when temperatures are between 60°F and 75°F. These grasses, common in northern climates, maintain their green color throughout the winter months because they are adapted to continue basic metabolic processes in the cold. Warm-season grasses must enter a deep state of dormancy when temperatures drop below a certain threshold, leading directly to visible browning.
Warm-Season Grasses That Go Dormant
The grass varieties that turn brown in the winter are exclusively warm-season types, utilizing dormancy as a defense against freezing conditions. The trigger for this color change is typically when the soil temperature consistently drops below 50°F to 65°F. Once this threshold is reached, the grass stops active growth and begins to conserve stored energy.
The most common warm-season grasses that exhibit this trait include Bermuda Grass, Zoysia Grass, St. Augustine Grass, and Centipede Grass. These turf types shed their summer green and take on a uniform tan or straw-like appearance throughout the cold season. Although they look inactive, the living parts of the plant remain safely insulated near the soil surface, ready to regrow when conditions warm up.
The Biological Process of Winter Dormancy
Dormancy is a protective, reversible state that allows warm-season grass to survive the cold until favorable conditions return. The process involves a dramatic slowing of the plant’s metabolic activity, effectively putting it into hibernation. During this period, the grass stops producing chlorophyll, the green pigment responsible for capturing sunlight and driving photosynthesis.
The plant redirects essential nutrients and carbohydrates away from the exposed leaf blades into the protected root system and the crown (the base of the plant). As chlorophyll breaks down and is no longer replaced, the green color fades, leaving behind the brown or tan color of the dried plant tissue. This survival strategy differentiates dormancy from actual winter kill or freeze damage, which is irreversible death of the plant tissue.
Winter Care and Recovery for Dormant Lawns
Caring for a dormant warm-season lawn focuses on minimizing stress to protect the living crown and root systems beneath the brown blades. It is important to reduce foot traffic and vehicle movement across the lawn, especially when the grass is frozen, as this can damage the plant’s growth points. Although dormant, the grass still requires small amounts of moisture to prevent desiccation, so light watering during extended periods of dry, windy weather is beneficial.
Homeowners should avoid applying nitrogen fertilizer during the winter, as this nutrient encourages new growth when the grass is attempting to rest and conserve energy. The grass naturally emerges from dormancy, known as spring green-up, when soil temperatures consistently rise above the necessary threshold. This signals the plant to resume active growth and ensures the lawn returns to its vibrant green color.