I bought this hydrangea 'Pia' in the spring. It has flowered well and I'm really pleased with it. I know I need to keep the flower heads on til the spring. However instead of moving toward autumn with the flowers losing colour but still looking nice, it looks appalling and black.
Has anyone seen this happen before? It's only in the last month that this has happened. It is in a pot, has wilted a couple of times in the heat so has been well watered and perked up both times.