Why are toadstools growing in my lawn?
What toadstools in a lawn are actually feeding on, why they appear in autumn, and the difference between harmless ones and a fairy ring.
- Difficulty
- beginner
- Time
- 20 min
- Read
- 3 min
- Safety
- caution
Short answer
Toadstools are the fruiting bodies of fungi decomposing organic matter under the lawn — usually buried wood, old tree roots or thatch. They are a sign of a living soil, not a disease, and they disappear on their own. Only fairy rings, which kill grass in an arc, actually damage the lawn.
The fungus lives underground all year as a network of threads. What appears in autumn is just its fruiting stage, triggered by mild damp weather, so removing the toadstools does nothing about the fungus.
Safety
Step by step
- Work out whether the grass is being harmed.Scattered toadstools with normal green grass around them are harmless. A ring or arc of dark green grass, or a ring of dead grass, is a fairy ring and behaves differently.
- Look for buried wood.Toadstools in one persistent spot usually sit over an old tree stump, a buried root, or timber left in the ground when the garden was built. That is the food source.
- Knock them off if children or pets use the lawn.Brush them off with a broom or pick them and bag them. It does not kill the fungus but it removes the immediate risk of something being eaten.
- Collect before they release spores.Removing them early reduces how many appear nearby next time, though it will not stop them entirely.
- Reduce the thatch.A thick thatch layer is the food source in many lawns. Scarifying reduces it and takes away what the fungus is living on.
- Improve drainage and air.Aerating and reducing surface moisture makes conditions less favourable. It is a slow effect but a real one.
- Dig out a stump if it is practical.Where toadstools mark a rotting stump, removing it removes the cause. Otherwise accept several years of autumn toadstools until the wood has gone.
- Treat a fairy ring differently.Fairy rings create a water-repellent layer that kills the grass in the arc. Spike the affected band deeply, apply a wetting agent, water heavily, and reseed. There is no domestic fungicide for it.
Tips
- Toadstools are the fruit, not the plant. The fungus stays whether you pick them or not.
- A ring of unusually dark green grass is the earliest sign of a fairy ring.
- One persistent patch year after year almost always sits over buried wood.
Common mistakes
- Applying fungicide to a lawn for toadstools — Domestic lawn fungicides do not control these fungi, which live deep in the soil on decaying wood. It is money spent on nothing.
- Assuming lawn toadstools are safe because they are in a garden — Several dangerously poisonous species fruit in ordinary UK lawns. Identification from photographs is not reliable enough to risk.
If it doesn't work
Scattered toadstools, healthy grass
Cause: Fungi decomposing thatch or buried wood — Fix: Brush them off. Scarify to reduce thatch. Nothing else is needed.
Dark green arc in the lawn
Cause: Fairy ring releasing nitrogen as it decomposes — Fix: Feed the whole lawn so the contrast is less visible, and monitor for a dying band.
Ring of dead brown grass
Cause: Water-repellent fungal layer in the soil — Fix: Spike deeply along the band, apply a wetting agent, water heavily and repeatedly, then reseed.
Same spot every autumn
Cause: Buried stump or root — Fix: Remove the wood if you can reach it, otherwise wait it out.
Questions people ask
Are the toadstools in my lawn dangerous?
Some UK lawn species are seriously poisonous. Treat every one as if it were, remove them where children or pets use the lawn, and never attempt identification for eating.
Will they damage my grass?
Ordinary scattered toadstools do not. Fairy rings do, because the fungal mat makes the soil repel water and the grass in the ring dies of drought.
How do I get rid of them permanently?
You remove the food source — reduce the thatch, and dig out buried wood or stumps where you can. There is no spray that clears them.