Is Your Lawn Suffering from Snow Mold?

As the last patches of snow melt away in early spring, you might notice something unsettling on your lawn: circular or irregular patches of matted, discolored grass that look gray, white, or pinkish. This is snow mold — a fungal disease that develops under snow cover during the winter months, and it is one of the most common lawn problems homeowners face after a long, snowy season.

What Is Snow Mold?

Snow mold is a cold-weather fungus that thrives in the dark, moist environment between snow cover and the ground. Unlike most lawn fungi that need warmth to grow, snow mold is most active at temperatures just above freezing — exactly the conditions found under a blanket of snow sitting on unfrozen or partially frozen ground.

There are two main types:

• Gray snow mold (Typhula blight) — the more common and less severe variety. It appears as circular patches ranging from a few inches to a couple of feet in diameter. The grass looks matted and grayish-white, and you may notice a web-like fungal growth on the blades. Gray snow mold damages the grass blades but typically does not kill the crown or root system, which means the lawn can recover on its own.
• Pink snow mold (Fusarium patch) — more destructive and harder to treat. Patches have a pinkish or salmon-colored tint, especially along the edges. Pink snow mold attacks the crown and roots of the grass plant, which can kill the turf entirely in affected areas. It does not even require snow cover — extended periods of cold, wet weather are enough to trigger it.

How to Treat Snow Mold This Spring

If you are seeing snow mold damage right now, here is what to do:

1. Rake the affected areas gently. Use a leaf rake or thatch rake to lift the matted grass and break up the fungal growth. This exposes the turf to sunlight and air circulation, which stops the fungus from spreading and helps the grass dry out.
2. Let it breathe. Avoid walking on or compacting the damaged areas. The grass needs airflow and warmth to begin recovering. In most cases of gray snow mold, the lawn will start filling in on its own within a few weeks as temperatures rise.
3. Reseed dead patches. If you are dealing with pink snow mold or large areas where the grass has been killed entirely, you will need to overseed once soil temperatures reach about 50 degrees Fahrenheit. Loosen the soil lightly, apply seed, and keep the area consistently moist until germination.
4. Hold off on fertilizer. Do not apply nitrogen fertilizer to snow-mold-damaged areas right away. High nitrogen levels can actually encourage fungal activity. Wait until the lawn is actively growing and has been mowed at least once or twice.

How to Prevent Snow Mold Next Year

Prevention is far easier than treatment. These steps in late fall will dramatically reduce your risk of snow mold the following spring:

• Keep mowing until the grass stops growing. Gradually lower your mowing height on the last few cuts of the season. Tall grass that folds over under snow creates the perfect environment for mold to develop. Aim for a final mowing height of about 2 to 2.5 inches.
• Rake up leaves and debris. Anything sitting on the lawn surface traps moisture and blocks airflow — both of which encourage fungal growth under snow. Clear all leaves, sticks, and garden debris before the first snowfall.
• Aerate in the fall. Core aeration reduces soil compaction and improves drainage, which helps prevent the waterlogged conditions snow mold needs to thrive.
• Fix low spots and drainage issues. Areas where water pools or snow accumulates in deep drifts are prime targets for snow mold. Fill low spots with topsoil and regrade any areas with poor drainage.
• Avoid late-fall nitrogen applications. Heavy nitrogen fertilizer applied late in the season promotes lush, tender growth that is more susceptible to fungal infection. Switch to a potassium-heavy winterizer fertilizer instead.
• Apply a preventive fungicide. For lawns with a history of recurring snow mold, a professional fungicide application in late fall — just before the first lasting snow — can provide a protective barrier through the winter.

When to Call a Professional

Mild gray snow mold usually resolves on its own with a good raking and some warm weather. But if you are seeing large areas of dead turf, recurring mold year after year, or patches that are not recovering by mid-spring, it may be time for professional help.

All Brothers Lawn Squad can assess the damage, reseed or renovate affected areas, and set up a fall prevention program so you do not face the same problem again. Reach out for a free estimate or call (765) 371-4186.