Answer: Unfortunately, it is very difficult to prune an ornamental tree that has outgrown its location. Heavy pruning will actually stimulate growth and the regrowth will be quite fast; it will also ruin the natural shape of the tree. The frequent pruning can weaken the tree's structure and allow insects or disease access as well. In general it is better to replace it with a smaller growing tree or large shrub that will fit the space when it is fully grown. If you really want to keep this one, I would strongly suggest you hire a professionally trained and certified arborist with experience in pruning ornamental (rather than orchard or woodlot) trees to consult with you on site and see what is possible. This will probably be more expensive than replacing the tree, but is the best way to explore your options for pruning.
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