Snow Mold in Illinois Lawns: Prevention and Spring Repair
Why gray and pink patches appear as snow melts on Lake County lawns, how to fix them, and the fall habits that prevent them.
Snow melts off in March and there they are: flat, matted, straw colored circles across the lawn, sometimes with a faint gray or pink cast. That is snow mold, and after a winter with long lasting snow cover it shows up on lawns all over Mundelein and Libertyville.
Two kinds, two outcomes
Gray snow mold is the common one. It works on the leaf blades but generally leaves the crown alive, so the lawn recovers on its own once conditions dry out. Pink snow mold, which has a pinkish cast at the edges of the patch, is the more serious of the two because it can attack crowns and roots and kill the turf outright.
Pink snow mold also does not require snow. It can develop in cold, wet weather any time from late fall through early spring, which is why you sometimes see it in a winter with little snow cover.
What to do in spring
Mostly, open it up and let it dry.
- 1Once the lawn has dried enough to walk on, rake the matted patches to separate the crushed blades and let air and sunlight reach the crowns.
- 2Give it two or three weeks of growing weather. Most gray snow mold areas green up on their own.
- 3Reseed the patches that stay bare, which are usually pink snow mold spots where the crowns died.
- 4Hold off on heavy nitrogen until the lawn is growing well, since early feeding can favor the fungus.
Prevention is a fall job
By the time you see snow mold there is nothing to prevent, so this is really about what you do in October and November.
- Keep mowing until growth stops, and take the last cut at about two and a half inches so blades do not fold over under snow.
- Get the leaves off before snow falls. A wet leaf mat under snow is the single biggest contributor.
- Avoid heavy nitrogen too late in fall, which leaves lush growth going into winter. The proper late fall application, made after growth stops, is fine.
- Do not pile plowed snow on the same section of lawn every storm, since deep piles stay frozen for weeks longer.
- Improve drainage in areas that stay soggy, because prolonged wet soil favors both types.
Fungicide is almost never worth it on a home lawn here. The exception is a property that suffers severe pink snow mold year after year, and even then the cultural fixes usually do more. If your lawn comes out of every winter looking beaten up, call or text 224-634-0673 or 224-200-8363 and we will look at what is driving it.
Frequently asked questions
- What causes snow mold on lawns?
- Fungi that stay active under prolonged snow cover on unfrozen ground, feeding on matted grass and leaf debris. Long lasting snow, tall grass going into winter, and leaves left on the lawn all increase the risk.
- Will grass recover from snow mold?
- Gray snow mold usually damages only the leaf blades, and the lawn recovers within a few weeks once you rake the patches open. Pink snow mold can kill crowns and roots, and those areas typically need reseeding.
- How do I prevent snow mold?
- Prevention happens in fall. Keep mowing until growth stops and take the last cut around two and a half inches, remove leaves before snow falls, avoid heavy late season nitrogen, and do not pile plowed snow on the same lawn area repeatedly.
- Should I use fungicide for snow mold?
- Rarely on a home lawn. Raking affected areas open and letting them dry resolves most cases. Preventive fungicide is reserved for properties with repeated severe pink snow mold damage, and even then cultural changes usually help more.
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Ruiz Landscaping serves Vernon Hills, Libertyville, Mundelein, Buffalo Grove, Lincolnshire, Long Grove and the rest of Vernon Hills's surrounding North Shore and Lake County communities.