Most Common Pruning Mistakes
During my career as a horticulturist I once worked as a landscaper. One of my duties was to prune trees and shrubs. We had demanding clientele who took pride in their pristine landscapes. I remember being terrified of cutting a huge hole into a shrub or cutting a plant too short. My boss use to always tell me “you can cut more off but you cannot glue it back on.” These were words to prune by.
There is nothing more noticeable than a poorly pruned plant. Pruning is a science and an art. The science involves recognizing plant flaws and eliminating these defects. The artistic end involves removing these bad parts or pieces without someone knowing the plant has even been touched. Improper pruning or pruning at the wrong time of the year can result in unsightly plants, reduced flowering, or plants that are more likely to be damaged by diseases, insects, or winter cold. It is important to remove the three D’s from any plant: dead, diseased or dying.
So what is pruning? Pruning is the removal of plant parts to improve form and growth. Branches are removed with minimal damage to cambium or growing tissue so that the wound will close in the shortest period of time and with the least possibility of wound infection.
So why do we prune? We prune to train the plant, maintain plant health, improve the quality of flowers, fruit, foliage and stems and finally to control growth.
Winter is the ideal time to prune. Trees are dormant and have no leaves, making it easy to see branches. Done correctly, winter pruning creates a burst of growth in the spring—in all the right places. On the flip side, bad pruning sets a tree up for failure. Here are some common pruning mistakes your likely to see in our area.
Topping: This is usually one of the most obvious and ugly of tree pruning mistakes. It happens a lot with crape myrtles (known as “crape murder”) and other trees that were too large for the place they were planted. With crape myrtles, it’s also done because people think it will get them more blooms (it won’t). Topping involves cutting away a large section of the top of a tree’s crown, or all the leafing branches across the top half of the tree. What you’re left with is a very ugly deformed specimen with a severely weakened branch structure.
Bad Timing: There are good times to prune and bad times to prune; it depends on the species and condition of the tree. Most tree pruning is done in winter to early spring in our area. If a tree is already stressed, it should not be heavily pruned. You should always have your trees inspected by a certified arborist before you let anyone take a chainsaw to it, unless you’re willing to lose the tree completely.
Improper Cuts: A very common tree trimming mistake when removing branches is to cut them off too close, or flush, to the main trunk. By doing this, you remove the branch collar; an area of tissue with specialized cells that help heal the wound. You’ll recognize it as a small swelling, or bump, right where the branch meets the trunk. The callous that the branch collar cells creates will prevent disease from entering the trunk. When you cut that branch off flush to the trunk, you’re opening a wound that can allow in disease and pests, putting your tree on a path to an early demise.
Over Pruning: No more than about 15% to 20% of a mature tree’s foliage should ever be trimmed off at one time. In fact, 5%-10% is usually adequate. When you remove too much of the canopy, you’ll leave the tree unable to produce enough food, transfer nutrients and structurally support itself. People often over trim and thin their trees in hopes of getting the grass beneath to grow properly (which rarely happens). If you have multiple trees in an area where you’d rather grow turf, often a better practice is to remove selected trees to let in more light, and perform structural pruning on the remaining trees so that you can have both healthy trees and turf.