Rumex - Bloody Dock Problem
I'm in zone 7. I have 3 Bloody Docks (Rumex Sangenius) that are about 5 years old and have come back every year. This year, they have come back very nicely but, over the last week or so, the leaves have started turning black and look they are rotting. Our temperatures are above normal (90s already) but I'm not sure that's the problem. Does anyone know anything about these plants? What should I do?