Fairy Rings
Risk near you, next 48h
See whether your local forecast favours this disease right now.
When it strikes
Watch it before you act
At this level the damage rarely costs the crop. Note the date, check twice a week, and act only if it reaches new growth or the weather turns favourable for it.
Wind-blown spores
Spores travel on air well beyond the affected bed, so a neighbouring garden can be the source. Spacing and airflow matter more than distance from your own infected plant.
It carries over to next season in soil, debris or seed — which is why rotation matters here, not just treatment.
Hot compost only
A heap that reaches and holds 55–65°C throughout will destroy it. A cool corner heap will not, and will return the problem to the beds with the finished compost.
When and where to look
Scout the planting while temperatures hold between 12°C and 28°C.
Rule these out first
Same category, and at least one host crop in common — so they are genuinely confusable in the same part of the garden.
The signs that lead here
Full problem lists for these crops
About
Fairy rings are made by soil fungi feeding on buried organic matter — old tree roots, builders’ rubble, buried timber. The ring is the growing edge of a single fungal colony spreading outwards at 15–30 cm a year, and it can persist for decades.
Symptoms
A ring or arc of unusually dark green, lush grass, often with a band of dead or thin turf just inside it, and sometimes a circle of toadstools after rain. The soil under a severe ring becomes water-repellent and the grass there dies of drought.
Organic Treatment
Spike the ring deeply and repeatedly, then drench with water plus a few drops of washing-up liquid as a wetting agent to break the water-repellent layer. Feed the rest of the lawn so the dark ring is less conspicuous, and knock any toadstools off before they shed spores.
Chemical Treatment
No fungicide reliably kills an established fairy ring. The only certain fix is excavating the affected soil to 30 cm and 30 cm beyond the ring, then returfing — a serious job, and rarely justified.
Prevention
Remove buried wood, old stumps and construction debris before laying turf. Keep the lawn well fed and aerated so the contrast is minimal, and avoid heavy thatch build-up.
Crops at risk
Related problems
Fairy Rings risk by location
Each location has a month-by-month profile computed from the weather archive: how many hours a year actually meet this disease’s thresholds.