Treating & Preventing Lawn Snow Mold

///Treating & Preventing Lawn Snow Mold
Treating & Preventing Lawn Snow Mold 2012-10-14T16:54:15+00:00

Article Written By: Reder Landscaping

I Noticed Dead Patches In My Lawn After The Snow Melted. Why is that?

As the weather warms and the snow melts away you may begin to notice small, circular grey, white or pink patches of fuzzy mold in your lawn. The grass in these patches may be yellowing or may appear completely dead. If so, your lawn is host to a widely spread, but fairly harmless disease known as Snow Mold.

Snow Mold occurs when snow accumulates and then remains undisturbed for long periods on wet, unfrozen grass. The snow cover blocks out the sunlight and dry air that would normally keep the mold in check, allowing the mold spores that are present everywhere in the air to germinate and spread in small patches throughout the lawn. The longer and more consistent the snow cover, the more incidence of Snow Mold is likely to occur. This means that areas with more snow, such as the edges of driveways and walks where snow is piled during shoveling, and where it takes longest to melt, are generally the areas hardest hit. Low lying areas where moisture collects are also more susceptible.

What Should I Do About My Snow Mold Problem?

In extreme cases Snow Mold can develop into other problems such as root rot and crown rot, which will permanently destroy areas of lawn. Often, however, the damage is slight and will be reversed once spring arrives and the temperatures rise and the grass blades are allowed to dry out.

The best course of action is to lightly rake the patches with a leaf rake to stand the blades up and to remove any damp, decomposing material. Proper spring fertilization will help develop new growth to replace the damaged areas. Keep in mind that it may take until late spring or early summer for these areas to recover.

If necessary in the case of seriously damaged areas, a grass seed that matches the surrounding lawn may be applied to the scratched up surface. Treat these new areas as you would any newly seeded lawn with proper moisture and fertilization in order to ensure good germination. Note that a non-matching seed will produce a permanently visible “patch” of lawn.

What Can I Do To Prevent Snow Mold?

Unfortunately Snow Mold is a fact of life when it comes to lawns and there’s no way to eliminate it completely. There are, however, some simple steps you can take to minimize it:

1.  Avoid fertilizing with high-nitrogen products late in the season (but do still winterize).

Like all plants in our area, grass plants go dormant in the fall as they prepare for winter. This involves “hardening off” or shutting down their growth mechanisms, losing their green color, and giving up moisture in their leaves to prevent damage during freezing temperatures. The application of nitrogen late in the growing season pushes all plants to continue their growth processes and even produce tender new growth as winter approaches. This means that winter may arrive before they’ve had a chance to harden off. Aside from damage caused by freezing, this new growth is more susceptible to infestation by Snow Mold.

“Winterizing” a lawn with an appropriate fertilizer is still recommended.  Winterizing formulas provide nutrients that promote root growth without the nitrogen that pushes excessive top or leaf growth.

2. Reduce watering in mid fall.

Reducing watering in the fall will help provide the signal to the plant that it’s time to begin shutting down and preparing for dormancy. A leaf full of moisture is a much easier target for mold.

3. Lower cutting heights in late fall to 2” or lower.

Lowering cutting heights will leave grass blades shorter and stiffer and will help prevent them from folding over and matting down. They’ll dry out more quickly in favorable conditions and make mold growth more difficult.

4. Remove leaf debris regularly.

Like snow, leaf debris provides a dark, damp cover under which mold is more likely to grow. Allowing leaves to sit on lawns for long periods late in the fall, or even until snowfall, gives Snow Mold a big head start.

5. De-thatch lawns with heavy thatch levels.

A dense mat of thatch also provides a good growing medium for Snow Mold, providing an area with dark cover and poor air circulation. If it’s excessive, removing it before winter is a good idea.

6. Aerate.

A healthy lawn is largely the result of a healthy root system, and nothing is better for promoting a healthy root system than aerating. By breaking up compacted soil, aerating allows more air, water and nutrients to get to the roots of the grass pants.  This promotes deep, strong roots which will make you lawn less susceptible to stress and disease.


Hopefully this information will prove useful. If we can answer any questions for you or be of help with any of your other landscape needs please feel free to call. In addition to lawn care and landscape management, we provide a complete line of high-quality landscape design and construction services.

Feel free to call us today if you have questions or would like to improve the health and appearance of your lawn and landscape.