I'm expecting to be dead before I move again, but if I'm not, I'd have to talk to the new owners and if they didn't want the plants or plan to take care of them, I'd make arrangements to either take them with me or give them to other gardeners I know. "Do you hear that Moby and Lori? You may need to make your beds larger. Much larger!"
It really is sad when people don't at least offer the plants to someone who would enjoy them. Mr Mom, did you not have a place to take the flowers when you moved?
Susan