Snow mold closeup
The mycelium of snow mold has matted over top of this patch of grass.
George Weigel

If your lawn went into winter looking lush and green but comes out of it with gray or pink matted patches, you’re likely seeing snow mold at work. Snow mold is a common cold-weather lawn disease. It’s caused by several strains of fungi that produce long, stringy growths called mycelium – the matting that you see growing over your once-green grass blades.

The good news is that while snow mold might look bad now, it seldom kills grass. Once the weather warms and dries, the disease typically goes away, and healthy grass starts growing again.

Gray vs. pink snow mold

Lawn grasses can run into two main types of snow mold – gray snow mold and pink snow mold. Both are most active when the lawn is damp and temperatures are just above freezing

Gray snow mold is more common at the end of winters that have had extended snow cover. The matting is whitish-gray in color and often happens along driveways, sidewalks, and other areas where piled-up snow has kept the areas dark and damp the longest. Gray snow mold usually kills only the grass blades and not the underlying crowns that push out new blades once the weather warms.

Pink snow mold can form even without a snow cover and in severe cases can kill the underlying grass crowns and roots in addition to the blades. Its matting has a pink tint to it. In many cases, end-of-winter lawns have an intermingled mix of the two types.

Snow mold in a lawn

Patches of snow mold formed over this lawn after the snow melted in late winter. George Weigel

What to do about snow mold

The best way to deal with snow mold is to prevent it in the first place. Grass cut short (down to about two inches) at fall’s final mowing dries out quicker over winter than the keeled-over blades of longer grass, counteracting the damp conditions that snow mold prefers. Raking leaves and other debris off of the lawn heading into winter also helps.

At winter’s end, rake and remove snow-mold matting and dead grass. That helps warm and dry the soil and clear the way for new growth. As the weather warms, you should see new grass growth emerging within two weeks. An application of spring fertilizer, such as Greenview Fairway Formula Lawn Fertilizer or GreenView Lawn Food with GreenSmart, helps the lawn recover.

Fungicides are almost never needed or recommended for gray snow mold, but several common lawn fungicides are labeled to treat severe cases of pink snow mold that persist in a wet spring. If there’s no sign of new grass after two to three weeks of raking and warm weather, dead patches can be planted with new grass seed.