Winter rains and damp conditions in many parts of California may have brought a surprise visitor to your lawn: mushrooms! A few mushrooms sprouting in your lawn can be a good sign: it means there's plenty of organic matter in the soil. But if patches of mushrooms are sprinkled across your lawn, something could be out of balance. Too much water, poor drainage, or too much shade can create conditions perfect for mushroom growth. So what can you do?
Tips for managing lawn mushrooms
Remove organic debris. Mushrooms in the lawn could be growing on excessive thatch, decaying wood or wood chips, or any other organic matter. Rake up the mushrooms along with the extra organic debris and dispose of them in your compost or municipal green waste.
Improve drainage. Mushrooms need a lot of water to grow. Level the ground so that water doesn’t pool, or install drainage solutions such as French drains, to help redirect water away from problem areas.
Reduce irrigation. In winter, when we have periods of rain, your lawn doesn't need as much water. Check your irrigation to make sure you're only watering when your grass needs it.
Aerate your soil. If the ground under your lawn is compacted, it won't drain as well, leaving extra water for mushroom growth. Use a core aerator to pull out plugs of soil and thatch.
Increase sunlight on your lawn. Mushrooms thrive in the shade. Trim trees and bushes that overshadow the lawn.
What NOT to do to manage lawn mushrooms
Don't mow them. While it may be tempting to mow down that patch of mushrooms, resist the urge. Mowing will spread the fungus more, causing an even bigger problem. Pick them out instead.
Don't let the mushrooms mature. Pick and dispose of mushrooms in the compost or municipal green waste before they open and release their spores.
Don't use fungicides. There are very few fungicides available to gardeners that are effective against mushrooms. Fungicides will kill the beneficial soil fungi as well as the mushrooms.
Don't eat them! Mushrooms growing in lawns are usually not edible. Many species are poisonous, and ONLY an expert can distinguish between edible and poisonous species.
For more information, see Pest Notes: Mushrooms and Other Nuisance Fungi in Lawns.