In the wake of this summer’s drought and heat, the fungi support networks in gardens are set to prosper once wet weather returns, provided there is sufficient rainfall. Following the drought in 2025, the RHS advice team received 43% more garden fungi enquiries than in the previous year, suggesting that this year’s more prolonged drought could trigger an even greater abundance of fungi fruiting in gardens and parks across the UK.
At RHS Garden Wisley in Surrey, early sightings of large rooting boletes as well as giant funnel mushrooms suggest that many species are poised to fruit prolifically once autumn rainfall becomes more established. As moisture returns to the soils, conditions are in place for one of the most spectacular displays of fungal fruiting bodies in recent years, including species such as fly agaric, giant puffballs and upright coral.
Drought affects both the habitat and food sources of fungi and these changes cue many garden fungi to reproduce. For example, saprotrophic fungi (which feed on decaying organic matter), such as portobello and oyster mushrooms, take advantage of the additional dead plant material resulting from drought. Similarly, heartwood decay fungi such as chicken of the woods and dryad’s saddle can flourish in drought years as more dead wood forms inside standing trees. Meanwhile, mycorrhizal fungi - including most boletes and amanitas - may receive stress signals from their partner trees which lead them to invest in reproduction and start a new generation in a more favourable location.
Jassy Drakulic, RHS Senior Plant Pathologist, said: “Gardeners may notice a remarkable variety of mushrooms and toadstools appearing in lawns, borders and around trees this autumn. While gardeners sometimes worry at the sight of mushrooms, the presence of fungi is mostly a sign of a healthy ecosystem. These fruiting bodies are just the visible part of extensive fungal networks beneath the ground or within wood, where they play vital roles in recycling organic matter, supporting plant health and helping nutrients move through the ecosystem.”
While most garden fungi are beneficial and play essential roles in soil health, a few can cause problems. The fungus most frequently reported to the RHS advice team is honey fungus, a pathogen of woody shrubs and trees.
Scientists at RHS Wisley are currently running a trial in which a bed of hydrangeas badly affected by honey fungus root rot is being inoculated with a beneficial fungus - sulphur tuft - to test whether it can out-compete the pathogen. While this is the first time the approach has been tested in a garden bed, lab-based studies have shown that sulphur tuft can out-compete honey fungus, providing early evidence that it may help reduce the disease. The trial will be rolled out at RHS Garden Rosemoor in Devon later this autumn.
RHS top tips for encouraging beneficial fungi in gardens of all sizes:
- Mulch regularly with organic matter - apply wood chip, leaf mould or garden compost to feed soil organisms and create favourable conditions for beneficial fungi.
- Keep some dead wood in the garden - log piles, stumps and decaying branches support a wide range of fungi that recycle nutrients and enhance biodiversity.
- Leave autumn leaves where they fall - leaf litter provides food and habitat for many fungi and helps build healthy soils.
- Let soil fungi establish naturally - including root-helping mycorrhizal fungi, by digging less and avoiding fungicides and synthetic fertilisers
- Be curious - as no UK fungi can harm through touch alone, it’s safe to get up close to appreciate their unique forms and familiarise yourself with the fungi in your garden.
