Blackberries overwintered well. I have been learning to grow blackberries for five years now, and every year I conduct new experiments on them. The first two years, in winter, several of my blackberry bushes froze and died. After I started cutting old leaves from the bushes in late autumn, this problem disappeared for me. I don’t bury or cover the blackberries for the winter; they overwinter as you see in this video. | Harvest Garden