In general, mature ornamental trees should be pruned just enough to maintain structure, health, and attractive appearance. This often amounts to minimal or only occasional pruning. Routine annual trimming is neither necessary nor advisable.
For large, potentially dangerous pruning jobs, such as removing heavy broken branches or limbs high in a tree, it's safest to hire a qualified professional.
Deciduous trees are usually pruned during the dormant season, while the tree is leafless and the branch structure is easy to see. In mild-winter regions, where one growing season blends into another, midwinter is generally the best time to prune. In cold-winter areas, late winter to early spring is the standard pruning period. When pruning a flowering tree, be mindful of when the flower buds form so that you won't inadvertently remove them. Trees that blossom early in the season, on the prior year's growth, should be pruned right after bloom. Those that flower later, on the current year's stems, should be pruned before spring growth begins.
Broad-leafed evergreens usually require very little pruning. When pruning is needed, do so during late dormancy or in summer; don't prune during or right after the spring growth flush. For flowering broad-leafed evergreens, timing is a bit more precise: like flowering deciduous trees, they should be pruned with an eye toward preserving flower buds. Prune after bloom for trees flowering on last season's growth; prune before spring growth begins for those that bloom on new growth.
Removing a tree limb
When removing larger branches, avoid ripping the bark by shortening the branch to a stub before cutting it off at the branch collar. Using a sharp pruning saw, make three cuts.
1. Starting about a foot from the branch base, make a cut from the underside approximately a third of the way through.
2. About an inch farther out on the branch, cut through from the top until the branch rips off; it should split cleanly between the two cuts.
3. Make the final cut by placing your saw beside the branch bark ridge and cutting downward just outside the branch collar. If the crotch is very narrow, cut upward from the bottom to avoid cutting into the branch collar.