Don Vandervort, Head Homeboy, has written more than 30 DIY home improvement books, been a segment host on HGTV, served as MSN.com's home improvement expert and written countless magazine articles.
Pruning trees is both a science and an art. With young deciduous and broad-leafed evergreen trees, proper pruning can ensure that a tree has a strong trunk and good structure. It's a process that takes several years, so be patient.
Deciduous trees are generally pruned in late winter or spring. Broad-leafed evergreen trees can be pruned at this time, but they can also be pruned during summer. Check flowering trees to determine if they flower on old or new wood. Those that flower on old wood should be pruned after they flower. Those that bloom on new wood should be pruned before growth begins in the spring.
Conifers (shown above) generally don't need much pruning. Avoid removing any lower limbs from a tree that has a natural pyramid shape. If a conifer has two upward-growing central stems, though, remove the weaker one. If you do need to prune, when and how depends on the growth pattern of the tree. Cedar, cypress, junipers, and random-branching conifers should be cut back so there is some foliage still in place. For fir, spruce, and pine with a whorl-type pattern, cut shoots back halfway or completely in early spring.
For the first year, simply remove any dead, diseased, broken, or crossed branches. The next year, start by encouraging a leader, a straight-growing upright branch in the center of the tree, as the dominant branch. Pinch or cut back side branches below this point, but don't cut them off completely. Gently prune for the next three to five years, never taking off too many branches in one year. Continue to encourage strong and well-placed branches. Look for branches that are set at wide angles to the trunk; these are generally sturdier. Also, remove any suckers, water sprouts, or wayward growing branches. Once strong side branches have reached a desired height, you can begin removing lower limbs.
With an already-established tree, prune to remove any dead, diseased, broken, or crossing branches. Also remove any suckers or water sprouts, weak limbs, or branches that detract from the overall shape of the tree. If the tree is very large, you may want to call in a professional tree trimmer.
