Thanks largely to the work of Dr. Alex L. Shigo and other scientists at the USDA Forest Service’s Northeastern Forest Experiment Station in Durham, North Carolina, much is now understood about a tree’s natural system of defense against infections from wounds. Based on this knowledge, these methods of making pruning cuts are recommended to help work with rather than against a tree’s natural tendency to wall off injured tissues and prevent the spread of decay. In these illustrations, final cuts should be made from points C to D. Do not cut along C-X, which is simply an imaginary vertical line to help you locate C-D. Wedel’s recommends applying pruning sealer to all cuts.
A free, hard copy of these directions is available here, at Wedel’s. Just ask for one the next time you stop by.
Pruning is done in order to shape a plant. Keep in mind the form you desire before starting to prune; otherwise you can get carried away! Many broadleaf evergreens, such as boxwood, should be trimmed after the new spring growth is finished for best results. Oftentimes boxwoods are trimmed into geometric shapes or even topiaries; however, they can also be left to grow more loosely. It’s also good for the shrub to be snipped occasionally throughout the growing season. Avoid pruning in fall, which could stimulate new growth before it had a chance to harden off for winter.