My Climbing Hydrangea has all its leaves wilting. There are no signs of bugs on the plant, and I have tried feeding it some 20-20-20 fertilizer to see if it would help. This has also been a very wet spring for the garden. What can be the problem with this plant?
Wilting in plants is due to a deficiency of water in the leaves and stems. It may be due to lack of water in the soil, to injury to the root system, root rot, or to the effects of various parasites (bacteria or fungi).
Climbing hydrangeas need rich, moist, well-drained soil. Hydrangeas need to be kept moist, but not too wet. If they are watered too much, or their roots are in poorly drained soil that has excess or standing water in it, they are susceptible to several kinds of root rot. The first is armillaria root rot, which can cause the leaves and the wood to turn brown. Unfortunately, once this has infected your plant it is unlikely to recover. The other is phytophthora root rot, which in addition to wilting, will cause yellow foliage.
Common diseases of hydrangeas are written up on the following website: