Hydrangeas are heavy drinkers and need consistent moisture, especially during hot weather. If they don't get enough water, the leaves and flowers can wilt and turn brown prematurely.
Most hydrangeas prefer partial shade, getting 4-6 hours of sun, especially in the cooler morning hours. If planted in too much direct sun, especially during the hot afternoon, the flowers can brown quickly.
Moving a hydrangea can expose it to stress and cause the leaves to brown, especially if it doesn't get adequate moisture after transplanting. Avoid moving plants in the peak of summer.
Applying too much fertilizer, especially in hot weather, can cause the leaf edges to turn brown. Use slow-release fertilizers sparingly, 2-3 times per year.
Various fungal infections can lead to brown spots on leaves. Improve garden hygiene by removing fallen leaves and use fungicides carefully if needed.
Excessive wind can dry out leaves, causing them to brown. Use physical barriers or plant in a less windy location.
If you notice browning, check your watering, sunlight, and soil conditions. Snip off affected flowers to promote new blooms. With proper care, hydrangeas can recover from browning.