Expect Mushrooms after a Rain in the Desert

Q. Mushrooms have sprung up overnight around some new daylilies we planted in a new raised bed. My husband thinks the soil the plants came in contained mushroom spores. We've never had mushrooms in our yard due to our dry air. Are these toxic? Will they hurt the plants?

Mushrooms popping up in some newly planted landscape plants

A. Don’t worry about mushrooms popping up in planted areas. This is quite normal, particularly after a rain, during periods of high humidity and particularly where there is shade. The potential for growing mushrooms exist anywhere dead wood can “rot” or decompose.

Mushrooms popping up in woodchip mulch after a rain

            Mushrooms pop up from soil mixed with woodchips, a thin layer of wood chip mulch on the surface of the soil, tree roots that have died, wood from construction that was buried and from the dead interior of trunks of even living trees.

Slime mold, another fruiting body of a fungus, popping up in a wet area of woodchip mulch

            Mushrooms are the sexual stage of many different fungi and easily identifies them as part of the “rotting process”. Sexual stage just means that these mushrooms release mushroom spores from the “caps” of the mushroom. The spores are moved about by air currents.

            A few fungi are “bad guys” and create plant diseases. Others are “good guys” and responsible for breaking down undecomposed wood into humus, compost or what might be called “black gold”. Your mushrooms are from “good guys”. But that doesn’t mean they are safe to eat!

            Most fungi that make mushrooms are classified as “saprophytes”. This term means they feed off only dead things, not living things. In other words, they are “decomposers” and not responsible for killing plants.

            Do not worry about these mushrooms harming your plants but I would still knock them over and let them rot so they aren’t accidentally eaten. Once knocked over, they will shrivel into nothing very quickly.

             Mushrooms oftentimes pop up after rains, during periods of high humidity, and disappear in two or three days when things dry out. The fungus network that created the mushrooms is still there, decomposing away, but does not send up any new mushrooms again unless there is rain or high humidity and plenty of wood to decompose.