Garden Detective

Mystery mushrooms invade her planter

What is that thing sprouting from the planter mix? It’s a Clitocybe tarda mushroom, sometimes found in California gardens.
What is that thing sprouting from the planter mix? It’s a Clitocybe tarda mushroom, sometimes found in California gardens.

Experts tackle readers’ garden questions.

Q: I have some kind of fungus growing in my planter soil. I used regular potting soil and a barklike mulch from The Home Depot. Can you tell me what the growth is, if it is harmful to dogs and how to get rid of it? I have tried to pull it out.

Peggy Mori, Sacramento

Master gardener Anna Symkowick-Rose: The photos you provided appear to show a mushroom of the common fungus known as Clitocybe tarda.

Fungi are common in barklike mulch and potting soil and are a natural part of the decomposing process. Many species are poisonous, and only an expert can distinguish between edible and poisonous species. (Clitocybe tarda is not considered poisonous.)

There are no simple tests to identify poisonous mushrooms. All obvious fungal structures should be removed from the yard before allowing children to play there. Pets also can be harmed by ingesting poisonous mushrooms.

Mushrooms are the visible reproductive (fruiting) structures of some types of fungi. Although the umbrella-shaped body is the most common and well known, mushrooms display a great variety of shapes, sizes and colors. However, regardless of the shape, the purpose of all fruiting bodies is to house and then disseminate spores, the reproductive units of fungi.

Fungi spores can travel far distances in the wind so they can easily come from neighboring yards. When spores reach a favorable place to grow, they germinate and send out long thin filaments called hyphae. Hyphae of some fungi will decompose wood, fallen leaves and other organic matter, absorbing a portion as food. Some fungi live in a beneficial association with plants, while others parasitize and cause plant diseases. Groups of hyphae can be visible as a mass of white or dark threadlike growth known as mycelium. When mycelium has sufficiently developed, fruiting bodies such as mushrooms can be produced.

The mushrooms can be removed simply by pulling them up; however, fungi can survive in the soil for years. Mushrooms often appear in mulch and compost when the soil remains saturated for long periods of time. Fungi also are more likely to appear in areas that do not have adequate drainage. If mushrooms appear during the heat of summer, it is often a sign that the area is being over watered. If this is the case, irrigation should be decreased and better drainage provided.

For more information on mushrooms and other nuisance fungi, check out the UC IPM Pest Note 74100, available free online at

The community also is invited to visit the Fair Oaks Horticulture Center, 11549 Fair Oaks Blvd. in Fair Oaks, to talk directly with Sacramento County master gardeners. For information on the center and a calendar of events, visit

Anna Symkowick-Rose is a UC Cooperative Extension master gardener for Sacramento County.

Garden questions?

Questions are answered by master gardeners at the UC Cooperative Extension services in Sacramento and Placer counties. Send questions to Garden Detective, P.O. Box 15779, Sacramento, CA 95852. Send email to h& Please put “Garden Detective” in the subject field and include your postal address. To contact UC Extension directly, call:

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