The sight of yellow or straw-colored grass in early spring is a frequent concern for homeowners as the snow melts and temperatures rise. While this discoloration may appear alarming, it is not always a sign of permanent damage. The lawn’s appearance is often a result of natural biological processes or specific winter-related stresses. Understanding the difference between normal dormancy and actual injury is the first step toward successful spring green-up.
Understanding Natural Winter Dormancy
For most lawns in temperate climates, yellowing is not a sign of poor health but a protective, physiological shutdown known as winter dormancy. Cool-season grasses, such as Kentucky bluegrass, fescue, and perennial ryegrass, thrive in temperatures between 60°F and 75°F. When ambient temperatures drop and daylight hours shorten, the grass initiates a metabolic slowdown to conserve energy.
During this process, the chlorophyll pigment breaks down, resulting in the dull, tan, or golden hue visible in early spring. The grass blades appear lifeless, but the plant remains alive at the crown, the growing point just above the root system. This state of rest persists until the soil temperature consistently reaches about 45°F, signaling the grass to resume active growth.
Specific Causes of Winter-Related Yellowing
Discoloration that is patchy, matted, or localized near hard surfaces is often caused by specific problems requiring intervention, differentiating them from natural dormancy. These issues represent actual injury to the turf that occurred over the winter months. Proper diagnosis is necessary because the treatment for one issue will not resolve another.
Snow Mold
Snow mold is a fungal disease that appears as the snow melts, often leaving circular, straw-colored patches across the lawn. Gray snow mold (Typhula blight) creates matted spots that can be several inches to several feet wide, sometimes featuring small, dark structures called sclerotia.
Pink snow mold (Microdochium patch) is typically smaller but causes more severe damage because the fungus attacks the grass crown, not just the blades. Both types thrive under the insulation of a deep, persistent snow cover, especially when the ground was not frozen before the snow fell.
Salt or Chemical Damage
Yellowing or browning near driveways, sidewalks, and streets is most often caused by de-icing salts, particularly sodium chloride. The salt crystals dissolve and saturate the soil, creating a high-salinity environment. This environment hinders the grass’s ability to absorb water, effectively causing a drought condition.
The resulting yellowing or brown “burn” is a symptom of desiccation, or severe dehydration. This damage is usually concentrated in strips along the edges of the pavement where salt runoff is highest.
Winter Desiccation/Drought
When turf is exposed to dry, cold winds without the insulating layer of snow, it can suffer from winter desiccation. This problem occurs when the ground is frozen, preventing the roots from taking up water to replace moisture lost through transpiration.
The dry wind removes moisture from the exposed grass tissue, leading to a straw-like, brittle appearance. Elevated areas or exposed slopes are particularly susceptible to this form of injury.
Promoting Recovery and Green-Up
The transition from winter to spring requires specific actions to encourage the lawn to break dormancy and repair any damage. Initial cleanup is the first step for all lawns, regardless of the cause of the yellowing. Lightly raking the entire lawn helps break up matted patches and removes winter debris, which improves air circulation and allows sunlight to reach the soil.
For snow mold patches, gentle raking is important to lift the matted grass blades and encourage drying, which stops fungal growth. If pink snow mold damage is extensive, the affected areas may require a fungicide application or eventual overseeding. Delaying the first spring cut until the grass actively grows and setting the mower to a high height (around three inches) will promote deeper root development.
To support renewed growth, address soil health. A specialized spring lawn feeding with a balanced, low-nitrogen fertilizer supplies nutrients without forcing too much tender growth too early. Nitrogen and iron are important for chlorophyll production. For areas damaged by de-icing salt, flushing is the most effective solution, involving saturating the soil with water multiple times to leach the salt ions out of the root zone.