Keep these rules in mind when you decide to prune, keep it healthy. Remove all dead, sick, or injured branches, keep it strong. Remove or reduce the length of the stems that compete with the main leader, keeping it even. Remove branches that cross or touch each other and those that seem out of place, keep it small.
Pruning occurs when branches are selectively removed from a tree. The goal is to eliminate unwanted branches, improve the structure of the tree and direct new, healthy growth. If you prune at the wrong time, you can damage the plant or eliminate its ability to flower year-round. As you can see in the graphic above, the worst time to prune almost anything is in late summer or fall.
Young trees that are improperly pruned or not pruned at all for several years may require intensive pruning to remove larger branches and prevent trees from deforming. If you remember the golden rule (prune for a reason), nine times out of ten you'll make a good decision for your plants and gardens, and your shrubs and trees will thank you for it with years of healthy growth. The last thing you want to do is pick up your clippers and go to town in your trees or shrubs for no good reason. Remember that each cut has the potential to change the growth of the tree, so it's important to set a goal for why the tree will be pruned.