Q: I planted a big ‘Green Giant’ arborvitae this year. It has one tall leader and 3 or 4 shorter leaders coming out of the rootball beside the main one. I would like to have just one leader so that as it grows taller, it won’t have multiple tops, just one. How would you prune this so as to end up with one leader, but not hurt the tree too much or make it look bad from pruning too much at one time?
A: Rick Smith (www.pruningguru.com) says he wouldn’t recommend doing this. When you separate the side spouts from the one you want to keep, it will expose a big brown patch that will not fill in very well..
You’re correct that it would look better with a single trunk but pruning should have been done when the plant was younger.
That said, if you pull the sprouts apart and think there is plenty of green foliage in the interior, it won’t hurt the tree to prune it.