I grew a batch of Apple seedlings for rootstock a few years ago. One that really did well I grafted over to Fuji this spring. It sent up four suckers after I too worked it. I would like to dig the suckers up and replant them for additional rootstock. Any advice? I live in zone 6, what time of year should I transplant? Shoul I cut them way back when I transplant, they are two to three feet tall now.
I don’t see any advantage to digging them now. I would wait until it’s nearly spring. Cut them way back to make up for root loss.
I would sever the root that connects them to the original tree so it can develop some of its own between now and the transplant.