Years ago, I lived next door to a man who kept an immaculate lawn. Edges trimmed with scissors-level precision. Stripes you could land a plane on. The kind of lawn that looked like it had been ironed.
One autumn, a cluster of mushrooms appeared near his apple tree. Nothing dramatic — a handful of small brown caps, the kind you'd see in any garden after rain. He was horrified. Within the hour he was out with a sprayer full of Roundup, dousing them like they were an invading army.
The mushrooms died. So did everything else within a two-foot radius. The grass turned brown. Then it stayed brown. For over two years, that patch was a dead zone — bare soil surrounded by otherwise healthy lawn. He never understood what went wrong. What he'd done was kill the thing that was keeping his garden alive.
What you're actually looking at
The mushroom you see above ground is a fruiting body — the reproductive structure of a much larger organism living beneath the surface. The real body is the mycelium: a vast network of fine white threads that can extend for metres in every direction. A single fungal network in a garden can cover an area larger than the garden itself.
This mycelium is doing essential work. It decomposes organic matter — dead roots, fallen leaves, old wood — and converts it into nutrients that plants can absorb. More importantly, it forms symbiotic relationships with plant roots called mycorrhizal associations. Through these partnerships, the fungal network effectively extends a plant's root system by orders of magnitude, supplying phosphorus, nitrogen, and water in exchange for carbon [1].
The ecologist Suzanne Simard has shown that mycorrhizal networks connect entire forests, allowing trees to share resources and even warn each other of threats — the so-called "wood wide web". The same networks exist in your lawn, on a smaller scale. When you see mushrooms, it means the system is working [2].
A sign of health, not disease
Mushrooms in your lawn tell you several things, all of them good:
- Your soil has adequate organic matter
- The soil biology is active — decomposition is happening properly
- Fungal networks are established and functional
- Your grass and any nearby trees are likely benefiting from mycorrhizal partnerships
Research published in Science in 2022 found that mycorrhizal fungi are responsible for transferring approximately 36 billion tonnes of carbon dioxide into soils annually — roughly equivalent to the amount emitted by the global fossil fuel industry. The fungi in your garden are, in their small way, part of the planet's carbon cycle [3]. Not bad for something people reach for the Roundup to destroy.
What happens when you poison them
When my neighbour sprayed those mushrooms with glyphosate, he wasn't just killing the visible caps. He was poisoning the mycelial network below — the living infrastructure that was feeding his soil, aerating its structure, and supporting his grass.
Glyphosate doesn't just kill plants. A 2021 study in Scientific Reports found significant reductions in fungal diversity in treated soils. Fungi produce glomalin, a glycoprotein that literally holds soil particles together — it's one of the main reasons healthy soil has structure rather than collapsing into dust. Destroy the fungi, and the soil structure goes with them. Water drainage changes. Compaction sets in. The patch becomes hostile to regrowth.
Two years of brown earth. Because he didn't like the look of a few mushrooms.
What to do when mushrooms appear
The honest answer: nothing.
Most lawn mushrooms are temporary. They appear after rain, persist for a few days, and disappear on their own. Fairy ring mushrooms grow in circles as the mycelium expands outward — the grass at the ring's edge is often greener than surrounding areas because of the nutrients being released. Ink caps dissolve into black liquid within a day or two. Puffballs sit there looking odd and then collapse. None of them are hurting anything.
If they bother you aesthetically, brush them off with a stiff broom or pick them by hand. They'll decompose naturally. What you should not do — under any circumstances — is spray them with weedkiller, pour bleach on them, or dig up the area. You'll damage the root system and the fungal networks that support it, and you'll gain absolutely nothing.
The real lesson
Gardens are not meant to be sterile. The best lawns — the ones that stay green through drought, recover quickly from wear, and resist disease — are the ones with the most active soil biology. Fungi, bacteria, earthworms, beetles: they're all part of the system. Every time you spray a chemical to eliminate something you don't understand, you risk breaking that system in ways that take years to repair.
At Albyn Fieldworks, we cut around mushrooms. We don't spray anything. We'd encourage you to do the same. If your lawn has mushrooms, your soil is alive. That's something to celebrate, not exterminate.
If you'd like us to look after your garden without the chemicals, we're here. And if you're interested in why the council takes a different approach, you might want to read our piece on weedkiller and our councils.
Notes
[1] The fundamental science of mycorrhizal associations is well-established. A good recent overview is Tedersoo, L. et al., "How mycorrhizal associations drive plant population and community biology," Nature Ecology & Evolution, 2023. For a more accessible introduction, Kew Gardens has an excellent explainer.
[2] Suzanne Simard's research on mycorrhizal networks in forests is summarised in her book Finding the Mother Tree (Allen Lane, 2021). Her foundational paper, "Net transfer of carbon between ectomycorrhizal tree species in the field," was published in Nature in 1997.
[3] Hawkins, H.-J. et al., "Mycorrhizal mycelium as a global carbon pool," Current Biology, 2023. The study estimated that mycorrhizal fungi channel approximately 13.12 Gt of CO₂ equivalent into soils per year, which was subsequently reported as ~36 billion tonnes using different accounting methods. Either way, the scale is staggering.
Albyn Fieldworks
Local gardener in Aberdeen & Aberdeenshire
