The Royal Horticultural Society (RHS) is considering moving its hydrangea collection from Wisley, Surrey, to its northern gardens in Greater Manchester and North Yorkshire as hotter summers threaten the plant's survival in southern England.
Hydrangeas top heat damage list
Data from the RHS gardening advice service shows inquiries about drought and heat damage affecting hydrangeas have more than tripled since 2023, making them the most frequently reported plant for hot weather problems. Hydrangeas rose from seventh to first place between 2023 and 2025 and remain the most reported plant suffering from drought and high temperatures in 2026. The RHS has more than 600,000 members, enabling easy identification of garden trends and concerns.
Move to northern gardens
The gardening charity is considering moving its hydrangea collection from Wisley to its northern gardens in Bridgewater, Greater Manchester, and Harlow Carr, North Yorkshire, where conditions are expected to remain more favourable and less hot and dry. Guy Barter, chief horticulturist at the RHS, 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."
Barter 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."
Study confirms climate impact
At its Bridgewater garden, the RHS conducted a study into hydrangeas and their performance amid climate breakdown from 2021 to 2025. The shrubs faced challenging weather including drought and record heat in 2022, heavy rain in 2024, and more hot weather in 2025, damaging plants and affecting blooming. The charity plans to send more plants north, including prize rhododendrons to Harlow Carr and Wisley's national collections of rhubarb and gooseberries to Bridgewater.
Some plants thrive in warmer conditions
While hydrangeas suffer, other plants are flourishing. Fig and almond trees are doing well in RHS gardens, and banana and lotus have flowered at Harlow Carr, which was not thought possible 10 years ago. Tim Upson, RHS 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."
Upson advised gardeners: "Move potted hydrangeas into dappled shade during extreme heat, water deeply rather than little and often, apply mulch to retain soil moisture and, where necessary, relocate plants growing in the ground in full sun to a cooler, shadier spot in the autumn."
