The hallmark of bad pruning? Branches that are chopped arbitrarily. This is driven by the view that if a tree no longer fits its allotted space, make it conform, no matter where the plant wants to branch or project its latent buds, no matter if this destroys its natural beauty. Art and science are crushed under the heel of utility.
It would be one thing if this were done by a well-meaning but misguided homeowner. To see it done by a crew of “professional” landscapers is disturbing. Apart from the butchery involved, the practice suggests to the neighborhood that this maiming is horticulturally correct and something to be aped.
You see this a lot with hybrid crape myrtles that want to grow to 30 feet. People think this lovely plant should stop at, say, 10 feet, and they chop away accordingly. In the first year, a cluster of aerial flowering shoots erupts below the cut. But with the natural lines of the tree destroyed, the owner has to cut back the fresh stems each winter before the next season’s growth. The result is an ugly knee at the end of the branches and continual rank growth.
If you want a choice little tree, pick a dogwood, a small crape myrtle variety, a deciduous azalea, a Winter King hawthorn or something named Hamilton’s spindletree.
This might seem obvious, but experience proves otherwise. The smaller the garden space, the greater the care that must go into plant selection. If I lived in an 18-foot-wide rowhouse, I would pick, say, a native fringetree or amelanchier before a large crape myrtle. And even when the choice is right for its space, you must prune for a plant’s health and beauty.
How do you prune a large crape myrtle? You should remove entire branches, but conservatively and over several winters. The object is to open up the tree to lighten its mass without losing its natural beauty or overall balance (as opposed to strict symmetry). The same principle applies to most other ornamental trees: redbuds, dogwoods, Japanese maples, stewartias, crabapples and Japanese cherries, for example.
The best time to establish the basic structure of an ornamental tree is in its youth, when pruning cuts are small and will heal quickly. The first candidates for removal are branches that are rubbing and growing inward. You’ll need to revisit the tree every winter, thinning congested branches in the developing, ascending canopy. If you go overboard with pruning, the tree will respond by sending up undesirable water sprouts.
Another basic and correct form of pruning is called heading back, which can be done now or during the growing season until about August. This technique involves shortening a stem to just above a dormant bud or side branch. If done now, the bud will produce a little branch this spring that will hide the cut. By selecting a cut above an outward-facing bud, you can direct the future growth.