I've got a three year old hibiscus in a pot that has suddenly turned black. Not all the leaves (yet) but most of them. I'm in the Florida Panhandle.. a few miles from the coast, so freezing is rare, but does happen.
The leaves are turning black, and those that are dead have what appears to be visible mold. Any idea what's going on here and what I should do?
You could try what they recommend:
I would remove all the affected leaves and spray liberally with an anti-fungicide. Keep your hibiscus as dry as possible, water at the bottom only, and plenty of sun. It could be a bacterial attack, but either way, you want to rid the plant of all infected tissue and soak it in an anti-fungicide (including the soil!)