Thank you all for trying so hard to solve my hydrangea problem. No, nothing drops off the roof or a tree. There is a good chance that workers dumped something toxic when the place was built 25 years ago, but I have dumped in so much new compost and super soil that I think that problem should have been solved. Although I occasionally watered the plant over the winter, I only gave it what it really, really needed. The hydrangea is now in a great big pot with good drainage, so I'm really hoping to see some leaves and hoping it will survive. There is a tiny bit of green under the bark. So that's a good thing. THANKS again friends!
