Gardeners are being urged to rethink where they plant hydrangeas as hotter summers leave the popular flowering shrub struggling in parts of the UK. The Royal Horticultural Society (RHS) says prolonged heat and drought are taking their toll, with the charity considering relocating part of its own collection from RHS Wisley in Surrey to its northern gardens, where conditions are cooler and wetter.
RHS Reports Surge in Hydrangea Heat Damage Enquiries
Figures from the RHS gardening advice service show enquiries about heat and drought damage affecting hydrangeas have more than tripled since 2023, according to The Guardian. The plants are now the most commonly reported to suffer during hot spells. Hydrangeas, known for their large pink, purple and blue blooms, have long been a British garden staple thanks to the country's traditionally mild and damp climate, but rising temperatures are making it harder for some varieties to survive, especially in southern England.
Expert Advice: Move Hydrangeas to Shade
Guy Barter, the RHS's chief horticulturist, said: "Hot dry summers are not the best for hydrangeas, although it is mainly the Hydrangea macrophylla types (mophead and lacecaps) that suffer most, especially in sunnier sites and sandy soils such as we have at Wisley." He added: "However, in light shade, north facing slopes or where the soil is a bit moister, they remain a fantastic plant for summer flowers, especially the more resilient Hydrangea paniculata. Our northern gardens have better soils and a superior climate for hydrangeas, hence the shift in emphasis. As the climate changes, bringing hotter drier summers, gardeners, like the RHS, will have to be more selective about where they plant hydrangeas."
The charity advises moving potted hydrangeas into dappled shade during extreme heat and watering them thoroughly rather than little and often. Applying mulch around the base can help retain moisture. For hydrangeas in the ground, the RHS recommends considering relocation to a cooler, shadier spot in autumn if currently in full sun.
RHS Director on Future Siting at Wisley
Tim Upson, the RHS's director of gardens, said: "We've seen first-hand at our gardens that hydrangeas growing in shadier positions cope far better during prolonged hot dry weather than those exposed to full sun and so we will need to think about where we site our hydrangeas at RHS Wisley in the future so we can continue to grow them." He encouraged gardeners to move potted hydrangeas into dappled shade during extreme heat, water deeply rather than little and often, apply mulch to retain soil moisture, and relocate plants in full sun to a cooler, shadier spot in autumn.
