root cutting

Hello! I picked up this dogwood scrub at my local nursery for $2. It was growing roots out if the bottom of it's container and is my root bound. Am I okay to root prune it now in Oregon? I feel so bad for the little guy, he's trapped!! Any advice would be helpful. Thank you

This tree was actually a root of my big pomegranate when I noticed it couldn't fit in the pot I just cut the root and plant it to see what would happen to it. well it sprouted and it is doing great. This one was repoted this year (maybe I shouldn't have) but it starting to show signs of growth...