Hydrangeas should be vibrant in summer, but many are wilting due to the UK heatwave, with temperatures reaching 32C in London. A common cause is incorrect watering, as highlighted by gardener Louise who shared a photo of her brown, flowerless hydrangea on the Hydrangeas in the UK Facebook page.
Louise asked for advice, and fellow gardeners noted the plant was likely underwatered and overheated. One user advised: “Underwatered, most likely. They also like morning sun and afternoon shade. Don't prune or deadhead the flowers till next spring after frost. Feed it, water it (don’t let it dry out at all, keep damp but not drowning), get position correct and hopefully will survive and next year come back healthy.”
Signs of underwatering include wilted, dry, crispy leaves, while overwatering causes yellow leaves and mushy stems. Water hydrangeas in the morning to allow absorption before heat; afternoon watering leads to evaporation, and evening watering attracts slugs. Water deeply once or twice a week, keeping soil moist but not waterlogged.
Avoid overhead watering, which only wets foliage and can cause fungal diseases. Instead, water at the base to hydrate roots. Also, check positioning: Louise’s hydrangea may be too close to a brick wall, which retains heat and can burn the plant. Ensure good air circulation around walls or fences.
