Please see attached photo. My hydrangea is not doing well! New growth looks ok, but it's leaves are a mess. I've not been good about watering this summer...is this just a result of being too dry? Or is there something more going on here? Should I leave it to recuperate over the winter, or do something to help before the frost comes?
Hydrangeas must have plenty of water. They will wilt otherwise, die, or be stressed and not do well. Water, water, water during dry spells. Especially in fall droughts. Fall droughts can be serious killers.
The spots are a fungal leaf spot that is fairly common. It does not kill plants. You can remove infected leaves at the end of the season. Mainly, just keep your plant as unstressed as possible--i.e. water when there is not about 1" of rainfall a week.