Heatwave putting hydrangeas at risk in south of England, warns RHS charity

By the Editorial Team · Thursday, July 30, 2026

The Royal Horticultural Society reports that rising temperatures and heatwaves have sharply increased heat and drought damage to hydrangeas, making them the most affected plant in southern England. In response, the RHS is considering relocating its hydrangea collections to cooler northern gardens and promoting shade-tolerant varieties to better cope with climate change impacts.

Hydrangeas, a popular summer-blooming shrub in Britain known for their colorful flowers that change hue based on soil conditions, are increasingly at risk due to rising temperatures and prolonged heatwaves, according to the Royal Horticultural Society (RHS). The society has highlighted a significant rise in concerns about drought and heat damage to hydrangeas, particularly in southern England, where this week’s heatwave has intensified pressures on these plants.

Data from the RHS gardening advice service reveal that queries related to hydrangeas suffering from heat and drought have more than tripled since 2023. Hydrangeas, which were previously ranked seventh in 2023 for heat-related issues, have topped the list as the most frequently reported plant affected by such conditions in both 2025 and 2026. This trend underscores the growing vulnerability of hydrangeas, especially the Hydrangea macrophylla varieties, which include mophead and lacecap types. These are particularly susceptible when grown in sunny locations with sandy soils, such as those at the RHS garden in Wisley, Surrey.

Guy Barter, RHS chief horticulturist, noted that while hot, dry summers present challenges for hydrangeas, plants grown in shade or on north-facing slopes with moister soil tend to fare better. He emphasized the relative resilience of Hydrangea paniculata species under these conditions, describing them as valuable for summer flower displays despite climate pressures.

The RHS is actively studying the impact of changing weather patterns on hydrangeas through trials at its Bridgewater garden in Greater Manchester. Between 2021 and 2025, the plants experienced a range of extreme conditions, from drought and record-breaking heat in 2022 to severe rainfall in 2024, followed by another hot spell in 2025. These fluctuations have damaged many plants and impaired their blooming performance, prompting the society to consider relocating its prized hydrangea collection from Wisley to gardens in northern England, where cooler and wetter climates are projected to persist.

This northern relocation strategy extends beyond hydrangeas. The RHS plans to transfer its collection of rhododendrons to the Harlow Carr garden in North Yorkshire, and national collections of rhubarb and gooseberries from Wisley will be moved to Bridgewater in Salford. Meanwhile, some species typically less associated with cooler northern climates, such as fig, almond, banana, and lotus, have thrived increasingly well in these gardens, reflecting broader shifts in plant viability due to climate change.

Tim Upson, RHS director of gardens, emphasized observations that hydrangeas placed in shaded environments demonstrated better survival during extended hot, dry periods compared to those exposed to direct sunlight. The developments at RHS gardens illustrate the complex challenges and adaptations facing UK horticulture as it contends with more frequent and severe weather extremes linked to climate change.

This article was reported by synthesizing coverage from multiple independent news outlets to present a balanced, unbiased account. Read about our editorial standards. Spotted an error? Let us know.