Some of my favorite clients have been guilty of the worst crimes. I recall a young professional couple who adored their plants, but felt compelled to keep them under tight control. The magnolias had been topped, the rhododendrons stripped, and the dogwood headed by the time I arrived on the scene. Most plants were sprouting shoots madly in an effort to regain the leaves they needed to survive. Usually well-intended but misguided pruning stems from the belief that trees can be molded into virtually any size or shape. A living tree is not lumber, however. It responds to excessive or incorrect cutting by sending up a forest of straight, skinny shoots called suckers or watersprouts. Cutting off the suckers the following spring-the typical reaction-causes even more of the unattractive shoots to grow in their place. The battle with Nature ends only when the gardener or the tree gives out.
Learning how to prune properly from the start certainly is the best way to avoid this scenario. But suppose you have recently changed residence and the previous owners’ pruning efforts already have taken their toll. Or perhaps you have, unwittingly, abused your own young trees with various and sundry hacking, sawing or chopping over the past several years. Don’t despair. You can take steps to set things right again.
The three most common forms of tree surgery malpractice are topping, or reducing the height by sawing limbs back; roundover heading, the shaping of trees into balls, corndogs or hamburgers; and overthinning, which includes stripping out all of the inside, lateral branches or taking off too many lower ones. These practices are considered “bad” pruning not because they are in poor taste, but because they backfire. Bad pruning locks you into a high-maintenance regime. In addition, it degrades the long-term health and beauty of your trees.
Aesthetically, pruning cannot accomplish what most people think it can, The bottom line: height and shape are determined by a tree’s genus and species, not by the way it is cut.
“Good” pruning, on the other hand, channels growth to better advantage via existing branches. Rather than try to halt growth by shortening all branches, the professional arborist relies on a “thinning cut” to remove certain branches completely, back to where they began as buds. The pruner selectively thins out rubbing branches to reduce bulk and clutter, and to admit more light and air. Thinning makes trees less prone to damage in windy areas. It also can mitigate the impression that the tree is “too big” for the site. Thinning includes removing some of the lowest branches as well, especially those that interfere with pedestrian or car traffic or those touching the house.
The sensitive pruner knows not only how to cut, but when to quit. Not all trees take well to thinning. A pine will layer out dramatically, but a cherry tree will sucker readily with even light thinning. Dogwoods, magnolias, crab apples and plums also are quick to sucker. Remove no more than one-eighth of the leaf canopy per year for these trees.
But how can you help the previously malpruned specimen now standing in your backyard? For starters, don’t feel too badly. Almost everyone has made some pruning mistakes, including many of the best pruners I know. Plants are very forgiving and most trees will reestablish themselves over time. If your tree is small, such as a young dogwood or Japanese maple, you can experiment with rehabilitative pruning.
Do nothing for the first several years. Living with your own or someone elses eyesore may be difficult, but if you prune suckers too soon, you simply worsen the situation. The suckers of a malpruned tree will grow straight up and will not arch until they reach the height the tree was before it was topped or stripped. Then, they will begin to bend gracefully and develop side branches and, eventually, will bloom again.
After three or four years, you can help restore your tree through careful pruning. By then, some suckers will have established themselves as the strongest and best new growth. Keep those shoots which head up and out from the center and those that fill an otherwise empty spot. Over the next few years slowly thin out the other, less desirable shoots. Remove those that are the weakest, face too far back toward the center, hang too far down, crowd or rub others. In this manner, prune both the crowded shoot clusters as well as the entire tree.
As with thinning, the greatest challenge of rehabilitative pruning is learning when to stop. Once you start, you probably will want to finish the job in one session, but if you do, you easily could find yourself back where you started. Think of your job as eliminating only the most offending shoots. Cut a few, then come back next year for more. As a rule of thumb, don’t remove more than a third of the growth in one year.
Remove suckers and shoots in the summer, when pruning is less likely to stimulate growth. (Avoid pruning during drought periods; pruning a topped tree in a dry August may kill the already stressed plant.) Be sure to cut off unwanted shoots cleanly. Prune them individually and exactly where they meet with the parent stem. Otherwise, you’ll create a nest of dead stubs.
By trying to cut off an entire group of stubs, you could aggravate the problem by cutting off new bark in the process. The wounded bark will respond with more suckers next year. In other words, don’t cut too close or too far away. Cut just right-flush with the trunk or parent branch. Occasionally, an entire, hopelessly crowded branch end (I call it a Hydra) can be thinned with a single cut.
In addition to removing suckers, eliminate any dead wood. Most mal-pruned trees have plenty of it, and should be cut out completely to avoid further degrading the tree’s health and appearance. Look for dead stubs and branches in the summer-they will have no leaves.
If your malpruned tree is large you’ll need to consult a professional arborist who can tell you whether the tree can be restored over 5-10 years , or whether it is a hazard and should be removed. Old topped trees are the ones most likely to fall on your house or drop a limb on your car. A topped tree rots slowly form the top downward, while regrowing weakly attached limbs and putting on girth. For such trees, the kindest cut would be at ground level.
