The sudden shift from a vibrant green lawn to a dull, brown expanse during winter often leads homeowners to believe their grass is dead. This color change is typically a natural defense mechanism that allows the turf to survive harsh conditions. Understanding the difference between this normal seasonal shutdown and actual winter damage is the first step in ensuring your lawn returns to a healthy green color when spring arrives.
The Most Common Culprit: Winter Dormancy
The most frequent reason a lawn turns uniformly brown is a biological process called dormancy, essentially a state of rest or suspended animation. This protective survival mechanism is triggered when soil temperatures consistently drop below approximately 50°F. The grass plant, particularly cool-season varieties like Kentucky bluegrass and fescue, conserves energy by halting active growth and reducing its metabolic functions.
During this period, the grass blade stops producing chlorophyll, the green pigment necessary for photosynthesis. The plant actively draws nutrients and energy back into its crown and root system, which remain alive and healthy beneath the soil surface. This cessation of chlorophyll production is what reveals the underlying brown and tan hues in the grass blades.
While cool-season grasses enter dormancy due to cold, warm-season grasses like Bermuda or Zoysia grass typically turn brown once the first frost hits.
When Brown Grass Signals a Problem
While dormancy is usually harmless, not all winter browning is normal, and localized brown patches often indicate damage or disease. One common cause is winter desiccation, which is extreme dryness that occurs when the plant loses more water through its leaves than its frozen roots can absorb from the soil. This damage is often seen on elevated or exposed areas where the turf is subjected to drying cold winds without the insulation of snow cover.
Another damaging cause is snow mold, a fungal disease that appears as matted, circular patches of discolored grass, ranging from a few inches to several feet in diameter, as the snow melts. Gray snow mold usually only damages the grass blades and is characterized by a white-to-gray web-like growth. The more damaging pink snow mold can kill the plant’s crown and roots, and it may appear with a pinkish cast at the edge of the patch when wet.
Browning along walkways and driveways often points to salt or chemical burn from de-icing products. Salt draws moisture out of the grass blades and roots, dehydrating the plant and creating toxic concentrations in the soil. This damage typically appears as straw-colored patches that are sharply defined by the areas where the salt-laden snow or runoff accumulated.
Irregular, winding trails of dead grass that become visible after the snow recedes are symptomatic of vole damage. Voles, or meadow mice, create runways under the snow, feeding on the grass blades to survive the winter, though they generally leave the plant’s crown and roots intact.
Ensuring Spring Recovery
To help your lawn recover, minimize foot traffic while the ground is frozen or saturated. Walking on frozen turf can snap the brittle grass blades and damage the plant’s crown, leading to noticeable brown spots in the spring.
For areas affected by snow mold, lightly raking the matted grass is beneficial once the snow is gone and the soil is thawed. This action breaks up the fungal mat, improves air circulation, and allows the soil to dry out, promoting new growth. In areas damaged by salt, a deep watering, or “flushing,” of the affected soil with fresh water once temperatures allow will help wash away the excess salt concentration.
Once the soil temperature warms and the grass shows signs of active growth, a balanced, slow-release fertilizer can be applied. This spring fertilization provides the necessary nutrients to fuel the growth spurt and helps the grass recover from any winter stress, ensuring a quicker return to a healthy green color.