Annabelle Hydrangea

This row of hydrangeas was a gift from my mom several years ago. I'm never sure if I'm doing the right thing... cut it back in the fall, don't cut back, when to cut blooms for drying (I think I finally have that right, anyway. First they're green, then white, then green again ~ then they will dry nicely. I planted them in the right place, too... because they have been doing very well. I have a pinkish mophead hydrangea in the back... and that one I think I got wrong, because this is the first year that it's bloomed. For those, I read that you shouldn't cut them back in the fall, because that's what the new blooms form on. I need more. Must have more.