I have an old Oak Leaf Hydrangea in my garden that I've had for about 15 years. I installed an irrigation system this year and misunderstood it's use. The result was a disaster. All the leaves (except for one branch on the bottom of the plant) have wilted and are dying. I'm not sure what I can do, if anything, to save the bush. Someone suggested I cut it back severely but it's an old woody plant and I'm not sure that's the right thing to do. Also the poor thing is so shocked, I figured it doesn't need any more drastic changes. Any suggestions? Or is there a person you could recommend who could come and take a look at it and give me expert advice? Alternatively can I send a photo? I'm so upset that I may have killed my beloved plant.
Leave the plant alone. It's the wrong time of year to prune it. Usually it is pruned after blooming. In the late spring it may leaf out again at the bottom of the plant even if the top dies back. You may miss a year of flowering but if you get fresh growth in late spring/early summer you can cut the dead parts out then.