Keeping a Eucalyptus Small
This question has probably been asked 100 times, but I've been growing eucalyptus gunni (cider gums) from seed. The pictures that I had seen showed a tree about eight feet tall with beautiful blue foliage. I've come to learn that the blue foliage only appears on new wood (easy enough to handle) and that the tree gets incredibly big with very invasive root systems. I've heard of polyurethane root barriers. I was wondering if these are strong enough to tame the roots of a cider gum, but also if I got one that was restrictive enough to act like a pot (like an in-ground bonsai) whether it would maintain the tree at a small height, e.g. 10 feet or so. Pruning the old would off to grow more new wood for the blue foliage is easy enough - but I want the tree to stay small.
Otherwise, is there a way to stunt the tree's growth, specifically to keep the trunk diameter reasonably sized? Or should I scrap the whole idea and just keep it potted?