Why mushrooms are growing in your artificial grass, and what it means

A mushroom is only the visible fruiting body; the actual fungus is a network of threads, called mycelium, spreading through whatever organic matter it is digesting. On turf that food source is usually one of a few things: scraps of wood or root left buried from before the turf was installed, wood mulch that has crept under the edge from a nearby bed, or a thick mat of decomposed pollen and leaf litter that has built up in the infill over a season or more. Mushrooms tend to appear after warm, wet weather, which is when fungi fruit, and they often show up in the same spot repeatedly because the food source underneath has not moved.

Pull one and look at the base and the surrounding infill. A ring or cluster growing from one point usually traces back to a buried chunk of wood or root right under that spot. Mushrooms scattered more generally across a shaded area point to a broader organic layer in the infill rather than one buried object. Either way, the fungus was there before the mushroom appeared; the mushroom is just the sign.

Pull the mushrooms and, where you can find it, remove the buried wood or root debris that is feeding them. For a broader organic layer, power brush to lift it and flush the infill so the fungus has nothing left to digest, then an antimicrobial to discourage regrowth. This is the same algae and mold removal process used for other organic buildup, since mushrooms, algae and moss all feed on the same kind of material.

Keep wood mulch pulled back from the turf edge rather than let it migrate underneath, and clear leaf and pollen debris from shaded spots regularly so the layer never builds deep enough to support fungus again. A spot that keeps producing mushrooms after a clean usually still has buried wood debris underneath that needs to be dug out once. Checking after a stretch of warm, rainy weather, when fungi fruit fastest, catches a new flush early, before it has a chance to spread spores across the rest of the yard.