The Strange Lawn Disease That Shows Up After Snow Melts

As winter winds down and your lawn starts to poke through the snow, you may notice that things look, well, off. If the melting ice is revealing ugly, fuzzy patches on your lawn, you could be dealing with a grass disease called snow mold.

It’s definitely not pretty to look at, and certainly not what you imagined for the background of your summertime family photos. However, you don’t need to lose any sleep over it—snow mold doesn’t cause long-term damage to your lawn, and getting rid of it is as easy as waiting for the weather to turn. 

What Is Snow Mold?

Snow mold is not a single disease, but a catchall term encompassing different types of fungi that thrive in low temperatures and poorly ventilated turf. 

There are four common types of snow mold, with pink and gray being the most recurrent. Each of these organisms has its own telltale characteristics that set it apart, but there are common denominators among them. 

Upon first inspection, snow mold appears as a nasty-looking patch of matted brown-grayish grass blades that emerges as the ice thaws in the months following winter.

Related: How to Stop Winter Weeds From Taking Over Your Lawn Come Spring

But don’t get it wrong—not all snow molds require snow to appear. 

"It can be a little bit of a misnomer,” says Kelly Kopp, extension water conservation and turfgrass specialist and professor in the plants, soils, and climate department at Utah State University. “Pink snow mold requires snow cover to become active and become an actual disease of turfgrass. But gray snow mold does not require snow cover.”

Snow mold thrives in high-moisture, low-temperature environments, meaning any part of your lawn that remained wet for an extended period of time. This includes the grass right under that shoveled pile of snow that took forever to thaw, or that corner of your yard you forgot to rake right before the first storm hit your town months ago. 

How to Identify Snow Mold

Snow mold treatment doesn’t vary depending on what organism has set up camp on your lawn during the winter. However, you still want to know which fungus you’re dealing with, lest your turf is suffering from another, more complicated health condition. 

The first thing you’ll be looking at is the size of the affected area. Kopp explains that snow mold patches can start out really small (around two inches in diameter) and expand to up to 12 inches or even a foot in diameter. Unfortunately, this is not enough to make a prognosis, as patches can easily merge and cover a larger area. 

Then, there’s color. As their name indicates, pink and gray snow molds feature, well, pink and gray colors. Kopp says hues may vary, but if you’re dealing with pink snow mold, you should be able to see “an honest-to-goodness pink color around the edge of these circles.” You might also see a water-soaked dark margin around the infected area. For gray snow mold, you’ll see discolored and somewhat bleached grass blades. 

Related: When to Fertilize Your Lawn After a Brutal Winter—Timing Is Everything

If looking at it closely still leaves you guessing, thinking about what type of winter you just went through might also help you solve the riddle of what type of snow mold is affecting your lawn. For example, if you experienced a lot of snow and steady low temperatures throughout the winter months, conditions might have favored the development of pink snow mold. If, however, you just went through a steadily cold winter with little to no precipitation, gray snow mold is the safest bet. 

Lastly, Kopp explains that some turf species are more susceptible to snow mold than others. Tall fescue, for example, is a more recurrent victim of the fungi, whereas fine-leaved fescue, perennial ryegrass, and Kentucky bluegrass are more resilient. Just keep in mind that it’s unlikely your lawn is entirely made of a single species, so even if your grass is supposedly more disease-resistant, that doesn’t mean it’s immune to snow mold.