Mushrooms in lawns?

Prolonged mild, wet weather tends to bring out mushrooms on lawns, so you can expect to see lots of them poke through lawns during the fall and the spring in the Northwest. Mushrooms are the “fruit” of fungi that live on underground dead or decaying matter, such as rotting tree roots or buried logs. In the soil and under bark, you’ll find a cluster of thin, white threads called mycelium. Because the mushrooms are only the “fruit”, removing them won’t kill the underground mycelium.

Some fungi such as fairy ring fungi can damage lawns, while many others are beneficial because they break down organic matter and release nutrients for other plants. Mushrooms that develop from decaying tree roots or other organic matter are generally harmless to lawns. Still, many people like to get rid of them because of their unsightly appearance, or they worry that children or pets may eat them. 

To get rid of mushrooms, rake or pick them off the lawn, or dig out the buried tree root or logs. The Washington State University Master Gardeners also suggest drenching the area with detergent and water in the early spring. The group advises: poke holes about 6 inches deep, about a foot apart, through the surface, and drench the area daily for a month. Use 1 to 2 quarts of water per square foot, with 1 to 2 tables of liquid detergent per 3 gallons of water. 

Removing excess thatch and aerating the soil to improve water penetration may also help. 

For more information on how to control fairy rings, which are circular or semi circular rings in the lawn, read this Master Gardener handout.