Two summers ago, we planted a row of hemlock to serve as a privacy hedge. They are planted about 4 feet apart and some are beginning to touch branches. Over last winter the snow depth exceeded the height of the tree and broke a few branches. Should I prune anything to make them stronger and grow together more quickly, or just leave them alone? If pruning is in order, should we prune now before the Pennsylvania winter months and while the tree is dormant, or wait until spring?