The sight of a brown, dormant lawn in winter often prompts homeowners to ask if the grass has died, or is merely resting. This color change is a natural survival strategy, not a sign of failure. Most grass is not dead, but has entered a state of suspended animation, patiently waiting for warmer temperatures to return.
The Difference Between Dormancy and Death
Dormancy is a protective, temporary state where a grass plant dramatically slows its metabolic activity to conserve energy and survive harsh environmental conditions. The trigger for winter dormancy is typically a combination of sustained cold temperatures and reduced sunlight. While the visible blades turn brown, the crown—a small, dense growing point located at or just below the soil surface—remains alive.
Actual plant death occurs when the crown tissue is destroyed, usually by extreme freezing, disease, or suffocation. Dormant grass will resist being pulled out during a gentle “tug test” because its root system is intact. Furthermore, an examination of the crown will often reveal a hint of green or white, confirming the grass is alive, while dead grass pulls out easily and has brittle, gray roots.
Biological Strategies for Winter Survival
To prepare for winter, grass initiates a process called cold acclimation, enhancing its freezing tolerance. The first element is the accumulation of soluble carbohydrates, such as sugars and fructans, in the crown and root tissues. These compounds function like a natural antifreeze, increasing the concentration of solutes within the cells to lower the freezing point of the water inside the plant.
Another element is the cessation of chlorophyll production, causing the grass to lose its green color. Since the metabolic rate is slowed, the plant stops producing the green pigment, diverting resources to storing energy instead of growth. The crown’s ability to resist freezing is further enhanced by reducing its moisture content, which helps prevent the formation of ice crystals that would rupture cell walls.
How Grass Type Affects Winter Behavior
The appearance of a winter lawn is heavily influenced by whether it is a cool-season or warm-season grass. Cool-season grasses, like Kentucky Bluegrass, Fescue, and Ryegrass, prefer temperatures between 50 and 80 degrees Fahrenheit and are adapted to colder climates. These grasses slow their growth and may even stay green through milder winters. They only enter a deeper dormancy when temperatures drop significantly below freezing for an extended period.
Warm-season grasses, including Bermuda, Zoysia, and St. Augustine, thrive in warmer climates, preferring temperatures between 80 and 95 degrees Fahrenheit. These varieties require a dormancy period when temperatures fall below 50 degrees Fahrenheit. They turn a uniform straw-brown color and remain that way throughout the winter.
Preparing Your Lawn for Winter
Preparation in the late fall maximizes the grass’s cold hardiness. The first is a final fertilizer application, often called a “winterizer,” which is absorbed by the roots and stored as carbohydrates in the crown for use during the winter and spring green-up. This late-season feeding is timed after the final mowing but before the ground freezes.
Adjusting the mowing height is important, as grass should be cut slightly shorter than usual, to about two to two-and-a-half inches, for the final cut. This height helps prevent the development of snow mold disease, which thrives under long grass blades matted down by snow. Removing fallen leaves and other debris is equally important, as they can block sunlight and trap moisture, encouraging disease and suffocating the dormant grass.