Avoid These 5 Common Pruning Mistakes

When performed properly, pruning maintains the health and beauty of a tree.  It is a blend of  science and art. If done hastily and improperly, it can cause irreversible damage and introduce diseases and pests.  Every pruning cut is a wound, and done correctly allows the tree to heal itself. There are common mistakes to avoid when pruning trees and shrubs:

1. Pruning without purpose
2. Poor cuts
3. Pruning at the wrong time
4. Dull and dirty tools
5. Over pruning

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Pruning Without Purpose
Knowing what you are trying to achieve determines the tools you will use and the cuts you will make.  Why prune plants?  Some reasons include:

• ​Maintain plant health.
• Remove dead, dying, diseased or damaged wood.
• Remove crossing or rubbing branches.
• Maintain air circulation within the plant.
• Remove unwanted shoots.
• Control size or maintain shape.
• Accentuate an ornamental feature.

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Poor Cuts

Stub cuts leave a stub of a branch that doesn’t allow the tree to seal off disease. If you can hang something off the end of a branch that’s been cut back, it’s a stub.

Flush cuts remove the branch collar—the slightly enlarged area around the base of a branch—and prevent the tree from sealing over the cut with a callus.

Heading cuts take off the end of a branch at a random point, leaving the tree open to pests and diseases and stimulating the tree to put out many weak branches at the cut end. Sometimes, the “pruner” may leave an undersized branch at the end of a large, structural branch.

Topping involves cutting a tree’s main trunk, or branch leader, at a random point to reduce the overall height of the tree. The trunk/branch leader is the most important part of a tree. It’s the reason a well-maintained, mature tree looks balanced. When a tree is topped it will usually respond by putting out a lot of “water sprouts”-- many long, skinny, suckering branches. (picture) Topping also results in lots more corrective tree work.

Over Lifting (Lion Tailing) removes interior branches, leaving only tufts of leaves and small branches at the ends of the large limbs. Trees suffer from malnutrition, sun burn, and increased limb breakage. Removing excessive amounts of leaves reduces the ability of a tree to make food. Exposing previously shaded bark to full sun causes it to split open, creating a wound. Reducing the branches to a small tuft at the end of a long limb creates a lever that catches the wind, often snapping the branch off.

Picture: TX Ch: International Soc. of Arboriculture

Don’t cut too far above a bud because the stub that remains will eventually die and rot providing an entryway for disease.

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Photo/Illustration: Dolores R. Santoliquido

Be careful not to cut too close to the bud. This damages the bud, leaving a dead stub. Don’t cut too far above a bud, either, because the stub that remains will eventually die, rot away, and provide a possible entryway for disease.

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Photo/Illustration: Dolores R. Santoliquido

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Pruning At The Wrong Time

Timing depends on growing season, bloom times,  and if the plant blooms on old or new wood. Cutting buds too early or late in the season results in lost blooms for the season. You must know the species, it’s condition, and the reasons you are pruning. As always, remove broken, dead, diseased, weak, or heavily shaded branches anytime. Diligent pruning will go a long way at preventing disease.  You can do light pruning anytime. Remove unwanted growth when the plant is young to prevent large wounds. Training trees for future form is critical and should be done as early as possible. Pruning early and consistently means better health for the plant and the pocketbook.

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Dull and Dirty Tool

Old, overused tools may be dull, which prolongs the healing process since branches are not cleanly cut. Besides, it makes your job more physically challenging. Sharpen your tools or look into investing in new ones. You wouldn’t want a doctor performing surgery with unsanitized surgical instruments, right? That analogy is not as crazy as you may think. After all, you are performing a kind of surgery on a living thing. If you are doing it without cleaning your tools, you may transfer soil-borne diseases.. Visit our blog, Ready, Set Grow  to learn about building your own DIY cleaning station.

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​Over Pruning

Never remove more than 25% from a mature tree crown or ⅓ of a shrub.  Although over pruned trees and shrubs don't usually die if some part of the canopy remains, the damage from over pruning can be extensive. Over pruning reduces the foliage that's available for making food for the rest of the plant.

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Picture from: The Spruce

While some gardeners consider pruning a relaxing, nurturing ritual, proper techniques are absolutely necessary to maintain the health of our beloved shrubs and trees.  The guidelines are pretty simple.  If you are new to pruning, it might be helpful to watch a few videos before you head outdoors to start snipping.  But once you get the hang of it, and you consistently use sharp, clean tools, you’ll be well on your way to a nicely-shaped landscape.

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For more information on pruning, visit these links.

 Penn State’s Extension articles on Pruning Shrubs and Trees

Almanac's Guide to Pruning 

Fine Gardening's Pruning Tips and Techniques
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