I rooted a couple hydrangeas and never did any pruning. They filled out more each year with more sprouts popping out of the ground each spring and growing taller each year. I realize you are 2 zones down from me, but it still freezes in zone 7. My BB dies to the ground each year with the first freeze...self pruning. If that didn't happen, I question if you have BB.

Thanks Sunnytop! That is what I was thinking but couldn't find anything to back me up. It did die to the ground last winter and I was afraid I'd lost it. I almost took it out but a neighbor convinced me to leave and see what happens in the spring. Glad I listened to her!