This summer I had some rogue Rose of Sharon stems growing within a Rhododendron. There were 5 of them. I pulled them out, including the root and transplanted them along the side of my patio to create a hedgerow for privacy. At this point they are doing well, but are tall and spindly. They vary from about 3-7 feet tall. (see picture) I would like to encourage some branching out along with some lower trunk development or perhaps an increase in the number of trunks.(I'm not sure if that's a good way to describe it.) At their young age I wasn't sure how far back they should be pruned. Any thoughts would be appreciated. Thanks!