A few mushrooms in a lawn are not necessarily a bad thing; in fact they are almost always a good thing! Mushrooms are the reproductive structures of fungi. Bacteria and fungi are the building blocks of a healthy soil. The presence of mushrooms is a sign that the soil is healthy. Living soils have the presence of millions if not billions of beneficial microbes and are teeming with beneficial bacteria, fungi, protozoa, nematodes, and earth worms.
Mushrooms are a clear sign of beneficial microbes at work in your lawn, which is all part of your lawn’s ecosystem.
Mushrooms are the sign of a fungi rich soil and mushrooms can only grow if there is a presence of organic matter that is derived from trees or shrubs. Fungi decompose lignin based organic matter and lignin is found in woody material like tree roots, tree stumps, tree leaves, decaying mulch, twigs, etc.
One of the benefits of fungi rich soils is that they will help with harder to digest tree leaves or stems that can build up in the thatch layer. Fungi produce a strong enzyme that is able to break down woody material and even animal bones. It is most common to find mushrooms next to the decaying organic matter that is more difficult to decompose.
Certain mushrooms can also be found under the drip line of trees, which can indicate a presence of mycorrhiza activity. Mycorrhiza (literally fungus roots) is a beneficial fungus that helps plants survive conditions of stress; such as low fertility, drought, temperature extremes, and root pathogens.
To reduce mushrooms that are growing in a lawn may need to help introduce more leafy material (think grass clippings and vegetable leaves vs tree leaves) into the soil. A good way to do this is to mulch the grass clippings to the soil. Bacteria-rich soils have more leafy-rich food present than woody-rich food. Fungi rich soils are more prevalent with lignin-based foods like tree leaves and decaying wood. If there is a neutral balance of bacteria and fungi in the soils then mushrooms will be less prevalent.
It is common to see mushrooms pop up when there have been periods of excess moisture, as this extra moisture can stimulate beneficial microbial activity. Mushrooms are not harmful to your lawn; in fact they are almost always a good sign! They are a clear sign that the soil is healthy, and a healthy soils is what we want for promoting healthy lawns and strong trees. Most often the mushrooms will disappear almost as quickly as they appeared.
If you have mushrooms in your lawn you now know that they are hard at work decomposing woody organic matter in the soil.
This lawn in Boulder Colorado has a bad mushroom problem that occurred after heavy rains. As you can see there is a tree stump very close to where these mushrooms are growing. The mushrooms are the fruiting bodies of the fungi that are feeding on the decaying tree stump.
We do not suggest applying a fungicide to the lawn as it will do more harm than good. Mushrooms are a sign of beneficial microbes at work in your lawn, which is all part of your lawn’s ecosystem. A fungicide will kill the beneficial microbial activity in the soil and cause the soil to die. Soils that are teaming with microbial activity are what we are striving for in organic lawn care and tree care. Killing the beneficial microbial activity in the soil, for the purpose of preventing mushrooms from growing in your lawn will have many adverse effects.
Just let the mushrooms be, they will typically disappear almost as quickly as they appeared.
There are many different varieties of mushrooms that can grow in lawns. It can be very hard to tell a poisonous mushroom from an edible one. It is extremely rare to find a deadly mushroom growing in a lawn but it can occur. The first time a poisonous mushroom was found growing in a Colorado lawn was in 2018. It is extremely rare to find a poisonous mushroom in a lawn but it is possible.
Please contact an expert in mushrooms before eating any mushroom that is found living in a lawn. If you are concerned about mushrooms in your lawn, you can pick and dispose of them to keep your dogs safe and kids safe. Always use extreme caution when handling mushrooms that you are unfamiliar with.