The Royal Horticultural Society has identified hydrangeas as increasingly vulnerable to Britain’s changing climate, with inquiries about heat and drought damage to the plants more than tripling since 2023. Data from the RHS gardening advice service shows that hydrangeas rose from the seventh most frequently reported plant experiencing hot weather problems in 2023 to the most reported in 2025, a position they have maintained through 2026.
In response to these trends, the RHS is evaluating a significant relocation of its hydrangea collection from its Wisley garden in Surrey to its northern facilities in Greater Manchester and North Yorkshire, where climate conditions are expected to remain more suitable for the plants. Guy Barter, the RHS chief horticulturist, explained that while certain varieties of hydrangeas remain viable under specific conditions—such as in partial shade or on north-facing slopes with adequate soil moisture—the hotter, drier conditions typical of southern England increasingly pose challenges, particularly for the more common Hydrangea macrophylla types grown in sunny locations with sandy soil.
A multi-year trial conducted at the RHS Manchester garden between 2021 and 2025 documented the stresses hydrangeas face under current conditions, including drought periods, extreme heat events, and variable rainfall patterns that have affected plant performance and flowering. The organization plans to shift additional collections northward, including prize rhododendrons destined for Harlow Carr in North Yorkshire and national collections of rhubarb and gooseberries moving to the Bridgewater garden in Salford.
While some plants are struggling with warming trends, others are adapting positively to changed conditions. Fig and almond trees are performing well at RHS gardens, and tropical species such as bananas and lotus have successfully flowered at Harlow Carr, developments that would have been unlikely a decade earlier. Tim Upson, RHS director of gardens, advised amateur gardeners to manage hydrangeas through strategic shading, deep watering practices, mulching for moisture retention, and relocating plants from full sun to shadier positions when necessary.
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