Mushrooms & Growths
Mushrooms, molds, and strange growths explained
Mushrooms and strange growths alarm people out of proportion to the risk they usually pose. Most lawn mushrooms are just the fruiting bodies of fungi breaking down old roots, stumps, or mulch — a sign of biological activity, not disease. That said, a few growths do carry a message worth hearing: shelf fungus on a living tree can signal internal rot, and any mushroom is a hazard if pets or toddlers eat things off the ground. These guides explain what each growth means, what it's feeding on, and the rare cases that justify action.
Mushrooms & Growths guides
White Mushrooms in Your Lawn: Why They Appear, What to Do White mushrooms popping up in a lawn are the fruiting bodies of fungi that are already living in your soil, usually feeding on decomposing roots, old stumps, or thatch. They surge after rain or heavy watering, and in most cases they're a sign of biologically healthy soil — not a lawn disease. The main job is keeping kids and pets from eating them. Read the guide → Black Spots on Siding Near Mulch: Artillery Fungus Explained Tiny black dots speckling your siding just above a mulch bed are most likely spore masses from artillery fungus, a mulch-dwelling fungus that literally shoots its sticky spores toward light-colored surfaces — siding, cars, downspouts, and windows. The dots look like flecks of tar, stick like glue, and are notoriously difficult to remove once cured. Importantly, it isn't a mold growing on your house: the fungus lives in the wood mulch below, and the fix is changing the mulch, not treating the wall. Read the guide → Mushroom Rings in Grass: What a Fairy Ring Is Telling You A circle or arc of mushrooms in your grass is a fairy ring: a single underground fungus colony that started at one point and has been expanding outward ever since, fruiting mushrooms at its edge after rain. Fairy rings are mostly cosmetic and notoriously hard to eliminate — for the vast majority of lawns, the right plan is managing the look and removing the mushrooms, not fighting the fungus. Read the guide → Orange Fungus in Mulch: Stinkhorns, Slime, and Siding Spots Orange growths in mulch are almost always fungi feeding on the wood itself — most often stinkhorns (the smelly orange fingers), orange peel fungus, or a slime mold. They're harmless to plants and people who leave them alone. The one mulch fungus that costs money is artillery fungus, which shoots tar-like black dots onto siding and cars. Read the guide → Shelf Fungus on a Tree Trunk: A Sign of Decay Inside the Tree A shelf or bracket fungus growing from a living tree's trunk is a red flag: it means the fungus has been decaying wood inside the tree, often for years, before producing that visible 'conk.' The tree may still look healthy, but internal decay weakens its structure — so the right move is an assessment by an ISA-certified arborist, not knocking the fungus off. Read the guide → Slime Mold in Mulch: The Gross-Looking Blob That's Harmless A foamy yellow, tan, or orange blob spreading across your mulch is almost certainly a slime mold — most often the species nicknamed 'dog vomit slime mold.' Despite the revolting look, it's completely harmless to plants, pets, and people, it usually rides in on fresh hardwood mulch, and it needs no treatment: rake it out, hose it apart, or just let it dry up on its own. Read the guide → Yellow Mushrooms in Potted Plants: Harmless or a Problem? Bright yellow mushrooms popping up in a potted plant are almost certainly Leucocoprinus birnbaumii, the flowerpot parasol — a tropical fungus that rides into your home in potting soil and fruits when conditions turn warm and moist. It won't hurt your plant at all; it lives on decaying organic matter in the mix, not on roots. The only real concern is that the mushrooms are toxic if eaten, so households with small children or pets that nibble should remove them. Read the guide →
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