That's weird, I just looked up the USDA map as I forgot if I was 5a or 5b (near Cleveland Ohio) and they upgraded my area to 6a. Interesting.

Anyway... this winter I wrapped my endless summer, burning embers, and (forgot, it's late) with burlap and stuffed with straw. They did OK last year (their first winter) but I didn't get very many blooms. After seeing some comparative pictures on here of covered hydrangeas in my zone, I decided to give it a shot. So, when do I un-wrap them and pull the straw away? Should I wait all the way until last frost?