When pruning your hedges and shrubs, be sure always to aim for a pyramidal shape -- wider at the bottom and narrower at the top. This is how hedges grow naturally, and it's for good reason: This way, sunlight, which is necessary for photosynthesis (which, essentially, keeps plants alive) can reach every part of the plant. If shrubs are pruned in such a way that the bottom ends up thinner than the top, the top branches will block sunlight to the bottom of the plant. That could result in dead branches at the base of the tree.
