We have a large (12 foot) hibiscus shrub in our yard that I severely over-watered recently (not knowing it was possible to do). To the point where lots of the ends of the branches are turning brown and dying. I've read about how to save overwatered *potted* hibiscus, but those strategies cannot be used because this one is a very large, in-ground plant. Is there anything that can be done to save it?