Leaves on a hydrangea, or any deciduous shrub, can wilt for a variety of reasons. Some are quite serious, while some are minor problems that gardeners can easily fix. Hydrangeas vary in hardiness from those that thrive in a wide range of conditions to those that are more sensitive and need special care to produce healthy leaves and flowers. Identifying the care needs of a particular variety can go a long way toward preventing problems.
Common minor causes
Lack of water is probably the most common reason leaves on any plant droop. If a plant is getting adequate watering, yet still appears to be wilting, one minor cause can be excessive soil drainage. Hydrangeas do well in rich soil with good drainage, but still need good moisture retention. Too much sand in soil can contribute to excessive drainage, which can lead to leaves drooping even when there is enough rainfall. Damage by burrowing animals can harm roots or create new, large drainage channels as well. Heat and sunlight can also cause leaves to lose moisture, even with good watering.
Verticillium wilt, one of the most serious plant diseases, can be a cause of drooping leaves on hydrangeas. This disease affects virtually every type of plant, although hydrangeas are less susceptible than some other flowering species. A fungal disease, verticillium wilt attacks the vascular system of plants, leading to poor absorption of water and transportation to the plant's leaves. Its chief symptom is asymmetrical damage, in which only some branches of a shrub fail to grow. Other diseases can also cause wilting, such as botrytis blight, also a fungus, and some insects, notably aphids.
If excessive drainage is the cause of leaves drooping, amend the soil around the hydrangea by digging in organic matter, such as compost, to correct the problem. Removing rodents from the area will also help, if they are the cause. In hot weather, watering extra in the evenings will prevent daytime leaf wilting. If a disease is causing the drooping leaves, the problem is more involved to correct. Identifying the specific disease and applying organic remedies can often save the plant.
Adequate site selection, with care taken to find a spot for a hydrangea with rich soil, is essential to preventing hydrangea leaves from drooping. Preventing disease by regular feeding, not growing shrubs in damp, musty areas and spraying with organic fungicides in the spring when it's damp are all preventives of disease-related wilting.