How to Treat Snow Mold in a lawn
What Is Snow Mold?
There are two types of snow mold that can cause damage to lawns: Gray snow mold and Pink snow mold. Both types become active during extended periods of snow cover, developing on top of the lawn between the grass and the snow. Snow mold typically occurs after a winter with prolonged snow cover where the snow does not fully melt for several weeks.
Once the snow finally melts, you may notice patchy or blotchy areas covered with a cottony webbing on top of the grass. This is snow mold, which will die quickly when exposed to warmer temperatures and sunlight. While snow mold does not damage the lawn itself, if it is left on the grass, it can block sunlight from reaching the grass blades, inhibiting the production of chlorophyll. Unfortunately, any resulting damage to the lawn may not become apparent until a few months later, when certain areas fail to green up properly.
Gray snow mold, also known as Typhula blight, is active in lawns at temperatures just above freezing. It appears as circular patches (6 to 12 inches in diameter) with a moldy appearance when the fungus is actively growing, which can be seen immediately after the snow melts. Under severe conditions, these smaller patches may merge to form larger, matted areas that appear dead. As the lawn begins to dry out, the fungal growth slows, and the patches can take on a light tan appearance, eventually fading to light gray or white.
Contrary to popular belief, late-season fertilization (often referred to as “fall” or “winterizer” fertilization) neither encourages snow mold nor increases its severity. In fact, applying fall fertilization can promote more rapid healing and recovery in lawns affected by snow mold damage.
Gray snow mold can be seen after the snow melts in a lawn. This is seen after the lawn has had a long period of snow coverage.
Why Chemical Treatments for Snow Mold are Unnecessary
Snow mold quickly dies when exposed to sunlight or when the area dries out. The activity of gray snow mold ceases when the surface dries or the temperature rises above 45°F. In contrast, pink snow mold can remain active during wet weather in the fall and spring, as long as temperatures are between 32°F and 60°F. While gray snow mold is common in Colorado, pink snow mold is rarely found in lawns across the state.
Symptoms of snow mold damage may appear in the lawn long after the mold is no longer active. Homeowners typically notice snow mold damage as circular, straw-colored patches surrounded by green grass. The affected areas often have a matted appearance and exhibit discoloration.
How to Prevent Snow Mold from Causing Damage to a Lawn?
The damage caused by snow mold is usually not severe. If the snow mold is minor, the affected areas will take longer to green up compared to the rest of the lawn. When the snow melts and the snow mold dies, it sits on top of the grass, blocking sunlight from reaching the turf, which prevents it from producing chlorophyll.
To treat and prevent snow mold damage, homeowners should gently rake the affected areas with a leaf rake. This raking breaks up the snow mold, allowing sunlight to reach the grass. The lawn should begin to green up within a few weeks after the snow mold has been disturbed or removed.
In severe cases, snow mold can cause significant damage, but this typically occurs if the mold is not broken up or removed. If left on the lawn for too long, the grass may die. In instances where permanent damage occurs, using a top seeding package may be necessary to repair the lawn. Fungicide applications are generally ineffective, as they do not prevent damage to the grass. Breaking up the snow mold is the only effective method for preventing harm to the lawn.
Damage from snow mold is most likely to occur on the north side of properties or in areas that do not receive much direct sunlight. While it is possible for snow mold to develop in very snowy and cold winters, south-facing slopes usually do not suffer from this issue.
Contact a Lawn Care Expert
Is your lawn damaged from snow mold? Do you need help repairing your turf?
Contact Organo-Lawn
Boulder (303) 499-2000
Fort Collins (970) 225-9425
What Does Snow Mold Look Like?
This is what snow mold looks like when it is still alive and growing.
This is grey snow mold in a lawn. It looks like cotton and has a sticky feel to the touch.
This is very fresh snow mold. This will die very quickly after exposure to sun and air.
The snow mold damaged all the areas where the grass is not green. There is some small green grass growing between the snow mold damaged areas.
Gray snow mold damage on grass a few weeks after the snow mold died.
This is a close up of what snow mold looks like on grass a few weeks after it has died.
This is a very common look of what snow mold damage looks like. Snow mold damage is not usually noticed until sometime in April.
Snow mold damage is not usually noticed by the homeowner until a few weeks after the lawn green up in the spring.
All the brown spots in the lawn are where the grey snow mold was covering the grass. The snow mold stops sunlight from reaching the grass.
Snow Mold Treatment FAQS
How to Fix a Lawn that was Damaged by Snow Mold?
To prevent and treat snow mold damage, homeowners should gently rake the affected areas of the lawn. This helps to break up the snow mold that is sitting on top of the grass, allowing sunlight to reach the turf and promoting healthy growth. The mold itself does not damage the grass directly but can prevent the grass from producing chlorophyll by blocking sunlight.
Raking with a leaf rake is typically sufficient to break up the mold. This action encourages the lawn to recover by allowing the grass to receive the necessary sunlight. If snow mold is minor, the affected areas will often green up more slowly than the rest of the lawn, but with proper care, the grass will eventually recover. Early detection and raking are key to minimizing the impact of snow mold on your lawn’s health.
