I have a white āAnnabelā and each year, in early spring, I prune it right back to 4-6ā. Thatās to make the stems strong enough to take the weight of v big flowers apparently. That was advice coming from loads of hydrangea experts. Each year I panic and think Iāve killed it, and each year, with regular water and loads of fertiliser, it shoots from the base. Every year Iāve been rewarded by enormous flowers that are the size of cauliflowers. My advice would be to water snd feed it and look out for shoots coming from the bottom. Good luck!
For easier duvet cover changing, Iāve just ordered some of these.