Snow Mold on Lawns: Identification, Treatment & Prevention

Those straw-colored patches and matted rings after snowmelt? Snow mold — a cold-tolerant fungus that thrives under insulating snow cover.

How It Develops

Snow insulates the ground, keeping it unfrozen while air temps drop. Slow melt creates prolonged cool, humid conditions perfect for fungal growth. The fungus attacks leaf blades, rarely killing crowns.

Treatment

1. Dethatch thoroughly — thatch holds moisture against grass.
2. Monitor 2–3 weeks. If new growth emerges, cultural care suffices.
3. Dead areas: overseed with resistant varieties (Kentucky bluegrass, fine fescue).

Prevention for Next Year

• Mow until growth stops completely — tall canopy worsens snow mold.
• Fertilize in spring (not fall) so nitrogen is used up before winter.
• Dethatch late fall to reduce pre-winter buildup.