Knowledgeable pruning
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When done properly, pruning contributes to the health and beauty of trees and shrubs. Improper pruning can damage and disfigure them. Learning some pruning fundamentals and knowing where to look for more in-depth pruning information can help gardeners improve the health and appearance of trees and shrubs and avoid some harmful pruning mistakes. While it's not possible to cover all aspects of pruning in a single newspaper column, I've included some of the basics as well as links to detailed information.
Pruning is not a one-size fits all undertaking. Different plants require different types of pruning so it's important to become familiar with pruning recommendations for a specific plant before picking up the pruning shears. It's equally important to know when to pick up those shears. Timing is critical. Some plants benefit from pruning in late winter, while others are best pruned in late spring or summer. Pruning at the wrong time can result in decreased flowering, stunted growth and pest and disease problems. Information on when to prune a specific tree or shrub is available from Iowa State Extension at yardandgarden.extension.iastate.edu/how-to/proper-time-prune-trees-and-shrubs and through your local Master Gardener program. In Clinton County, the Master Gardener Hotline number is (570) 858-0198.
For those undertaking pruning for the first time, a good place to start is by removing dead wood. It's a safe way to build up your confidence, because the shoots and branches you are pruning out are already dead, so you don't have to worry about harming them. In fact, removing dead, diseased and severely damaged twigs will allow more light and air to move through the plant, making it less hospitable to pests and diseases while stimulating new growth.
Once you have removed the dead, damaged or diseased wood, inspect the plant for branches that are rubbing against each other or growing inward toward the center. These should be removed. The rubbing will scrape off the bark, providing an opening for pests and diseases. Inward growing shoots limit light and airflow and can interfere with healthy structural growth.
With dead wood and crossing branches removed, it's time to decide if further pruning is needed. The decision to prune further depends upon the condition of the plant and its function in your landscape. If you planted a fruit tree to provide apples, pears or other fruits, your approach to further pruning will not be the same as pruning an ornamental flowering tree or shade tree. Detailed pruning information is available from University of Minnesota Extension at extension.umn.edu/planting-and-growing-guides/pruning-trees-and-shrubs#general-pruning-guidelines-1335960 and from University of Maryland Extension at extension.umd.edu/resource/pruning-shrubs-and-hedges-home-garden/.
Pruning tools such as shears, loppers and saws can transfer disease organisms from one plant to another. They should be sanitized regularly as a preventative measure. This is especially important when the tools have been used on diseased plants. Sanitizing can be done by removing dirt and debris and then dipping tools in rubbing alcohol. Alternatively, they can be soaked in a solution of one part bleach and nine parts water for at least 10 minutes, then rinsed and dried. There are pros and cons to each method. Alcohol is readily available and can be used right out of the bottle, no mixing required. However, it may not be as effective as a bleach solution when dealing with apple and pear trees affected by fire blight (Erwinia amylovora). Bleach can be harmful to humans and corrosive to metal tools, so care must be taken when using it. After rinsing off the bleach solution, tools can be dried and oiled to reduce corrosion.
I want to point out two things that should be avoided. Number one on my list is "tree topping" or "hat racking." This involves cutting off tree limbs to remove large sections of a mature tree until it resembles a hat rack, hence the common name. Doing so is extremely harmful to the tree and unsightly to the eye. It increases the tree's susceptibility to pests and diseases and starves it of nutrients. The practice was discredited years ago but unfortunately is sometimes still used. I cringe whenever I see it. After having its limbs amputated, the tree will try to recover by pushing out a multitude of new shoots, which will unfortunately be very weak. The tree will try desperately to replace its canopy of leaves so it can photosynthesize and feed itself. In some cases, the tree will struggle for years, in others, it will just die.
Also on my list of things to avoid is pruning to keep a tree or shrub small when it naturally has a very large form. Because the plant is programmed to achieve a certain size at maturity, it will continue trying to do so, and will have to be pruned repeatedly to keep it small. That makes additional work for the gardener and stresses the plant. A better alternative is to do some research before making a purchase. Select a tree or shrub that will reach a mature size suitable for the location.
If you're staying inside to avoid the weather and have an interest in pruning, I hope you'll take the opportunity to visit some of the links I've included and learn more about it. Your trees and shrubs will thank you!
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Debra C. Burrows, PhD, is a retired Penn State Extension Educator and a certified Master Gardener. She can be reached at dcb3@psu.edu.