Posted: 15/05/2016 at 09:01
I suppose it might be that potted plants have more of a confined root space than they would do in the ground. So those that are already in the ground have a deeper root run.
Having said that, I'm moving things around all the time at the moment. I take as much as the rootball I can get, good drink in their new position and this generally works well. They might flop over for a bit but provided the new site isn't in direct sunlight when replanted they usually bounce back.
Plants with lots of green and emerging flowers I either leave or cut back before I move. I think the general advice is spring and autumn is the best time for replanting. Sometimes it does depend on the plant. I've been growing a lot of honesty which has a large tap root so the plant can't be uprooted and moved.