If the thought of cutting into what looks like a perfectly happy plant makes you cringe, you're not alone. Even homeowners who know the benefits of pruning—better health, more pleasing habit, bigger flowers—are often still confused about exactly the right time and right way to make the cuts, fearing they'll lop off next year's flowers, stunt the plant's growth, or kill it outright. But once you understand how plants respond to pruning, you'll realize how many problems a well-placed cut can solve.
The first step to successful pruning is timing it right. Shrubs that flower on new wood, or branches that form in spring and flower in summer—rose-of-Sharon and summersweet are two—should be pruned in late February or early March. This results in fewer but larger flowers the first year. "Pruning distributes the plant's stored energy among fewer flower buds so that the ones left behind get more to eat," explains horticulturalist Lee Reich. Prune spring-flowering shrubs right after they bloom, giving them the rest of the growing season to develop new branches and buds, since these bloom on old wood, or last season's growth. "But if you miss the ideal time to prune, you can always wait until the shrub's flowers brown out," says This Old House landscape contractor Roger Cook.
Successful pruning involves mastering two basic cuts. Follow along to learn how to use them to remedy common problems you encounter.
"To deal with a wayward evergreen branch, be sure to cut it back to the center of the shrub, where it meets another stem. If you just lop off the offending section, the cut stub will be obvious and unsightly."—Roger Cook, TOH landscape contractor