Fall & Winter
Snow mold on Minnesota lawns last spring: what to change this fall
Snow mold hit many Minnesota lawns last spring. Learn the fall changes that reduce it: final mowing height, leaf handling, and fertilizer timing.
Wet Leaves Under the First Snow Are How Snow Mold Gets Started
Snow mold doesn't start with snow. It starts with matted leaves and long wet grass going into winter. Why fall cleanup is the best snow mold prevention a homeowner has.
Jack · golf course superintendent·2 min read·October 5, 2026
Every spring, someone finds gray or pinkish circles in the lawn as the snow melts and asks what happened. Most of the time, the answer goes back to October: a lawn that went into winter long, wet, and covered in leaves.
What snow mold needs
Snow mold is a group of fungi that grow in cold, wet conditions, just above freezing. They don't need warmth. They need moisture and cover.
- Gray snow mold usually needs a long stretch of snow cover, often 40 to 60 days or more.
- Pink snow mold doesn't need snow at all. Cool, wet weather is enough.
Why leaves make it worse
A layer of wet leaves on the grass does what snow does: it traps moisture, blocks air and keeps the grass blades wet for weeks. Put snow on top of that, and you've built a perfect home for snow mold.
Long grass does the same thing. Tall blades flop over and mat down under snow.
What to do this fall
- Get the leaves off, or mulch them fine. Run the mower over light leaf cover until the pieces are small and fall between the blades. Heavy cover needs raking or bagging. See mulching leaves into the lawn.
- Keep mowing until the grass stops growing. Then give it a final cut a bit shorter than usual. See when to stop mowing for the season.
- Go easy on late nitrogen. A big dose of fast-release nitrogen right before winter gives you soft, lush grass under the snow, which snow mold loves. See late-fall fertilizer.
- Don't pile snow in the same spot all winter if you can help it. Big piles from the driveway take the longest to melt.
If you get it anyway
Most home lawns recover from snow mold on their own. In spring, rake the matted patches lightly so air gets in, and the grass usually grows back as it warms. See snow mold prevention and recovery.
On golf courses, we spray preventive fungicide on greens because they're cut so short. On a home lawn, good fall cleanup does most of the work.
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