If You Have These Kinds of Trees in Your Yard, This Is the Best Time to Prune Them
Trees are valuable assets in any yard, providing shade and adding beauty while also serving as a draw for wildlife. While trees are largely self-sustaining, you do need to prune them to maintain their health and cull dead limbs that threaten your home. But unless you know the proper way to prune a tree, you can do more harm than good. Ahead we take you through how to prune trees with help from Kaustubh Deo, ISA-certified arborist and general manager for Seattle-based tree management company Blooma Tree Experts.
Why You Should Prune Your Trees
There are many reasons why you should prune your trees:
- Trains young trees: Pruning young trees is particularly critical in ensuring they grow properly by directing new growth and eliminating overcrowding in a tree’s branches.
- Makes it stronger: Pruning away limbs helps improve the balance of a tree, making it less susceptible to damage from high winds, snow and ice.
- Disease prevention: Removing dead limbs and thinning out a tree's canopy makes it less vulnerable to disease.
- Eliminates hazards: Removing dead limbs and branches reduces the likelihood that falling branches can cause injury or property damage.
- Improved aesthetics: Trimming a tree can make it more appealing by shaping it and thinning out crowded branches.
- Functional: Sometimes trimming is necessary to prevent trees from growing into structures or power lines.
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When Should I Prune My Trees?
Deo says when you should prune your trees depends on the type of tree and where you live:
Deciduous non-blooming trees: The best time to prune deciduous trees is during late winter when the tree is dormant, which allows it to recover rapidly when spring arrives.
Spring-blooming trees: Prune spring blooming trees, such as dogwoods, magnolia, redbuds, and flowering cherries, in the spring just after the tree’s flowers begin to wither. This ensures you won’t accidentally trim away emerging buds.
Evergreens: Prune and shape evergreens in the late winter and early spring to reduce stress on the trees. This time is ideal as you can pinch back emerging “candles” in late spring to keep the evergreen compact.
If you’re conducting a more extensive pruning job, Deo says it’s best to do it in the winter. “This gives the tree time to heal from the pruning wounds while not also dealing with intense sun and low water,” he says. “It's also great that insects are less active, making it less likely that the tree would have a pest-infestation after the pruning.”
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What Tools Do I Need to Prune a Tree?
- Hand pruner: Good for cutting away smaller branches under an inch thick.
- Loppers: This tool can take out branches that are under two inches thick.
- Pruning saws: You’ll need this for branches between two and four inches thick.
How to Prune a Tree
There are several methods you can use to prune a tree.
Follow the 5 D’s Rule
Start by picking out limbs that aren’t healthy by using this rule. Look for branches that are dead, damaged, diseased, dying, or deformed.
Other Branches to Trim
After identifying the obvious unhealthy branches, now look for others:
- Crossing/rubbing: Look for branches that are growing into each other or rubbing against each other, causing damage where they touch. Trim away one of the branches.
- Inward-growing: Eliminate any branches that are growing inward toward the trunk of the tree.
- Weak branches: Cut away any branches that are growing from the trunk at a sharp angle, typically less than 30 degrees in relation to the trunk.
- Suckers: Prune any trees that are growing from the base of the trunk.
- Hazards: Trim away any branches that are interfering with walkways or growing into structures. You should also clear away any limbs interfering with power lines but should contact a pro for this.
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What to Know About Crown Raising
In some cases you may need to raise the crown of the tree to allow for views or make way for traffic. Rather than doing this in one pruning session, gradually raise the crown over a period of years to avoid overstressing the tree. The crown should always make up at least 60 percent of the tree. Raise the crown further than that and you risk weakening the tree.
For Larger Branches, Use the 3-Cut Method
- Locate the branch collar, which is the swelling that occurs right where the branch starts growing out of the tree.
- Undercut the branch 6 to 12 inches from the trunk to prevent bark stripping on the trunk.
- Follow that up by cutting the branch several inches further out from the first cut until the limb drops. If there's any bark tearing as the branch drops, it will stop where you made the undercut.
- Now make a final cut just outside the branch collar.
- For branches under two inches thick, use loppers to take the whole branch off in one cut.
Deo says it’s important to limit pruning. “Each time you prune, you are causing an injury to the tree that it needs to recover from,” he says. “Never prune more than 15 percent of a mature tree's canopy and no more than 25 percent of a young tree's canopy away. Doing so can stress the tree, making it susceptible to disease and pests and trigger weak growth.”
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Common Mistakes When Pruning a Tree
- Lion’s tailing: Avoid lion’s tailing when pruning, which is the act of pruning out all the interior growth on a limb, leading to a limb that looks like a lion tail. “Instead, make targeted cuts on the end of a limb, cutting back to another node on the tree that is at least half or two thirds as large as the end you are cutting,” Deo says.
- Cutting the branch collar: Making a cut that removes the branch collar can cause the pruning cut to heal more slowly or not at all, causing rot to spread into the trunk.
- Topping or rounding: This practice of aggressively cutting back large branches of the tree can send it into shock, resulting in weak, uneven growth and shortening the tree’s lifespan.
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When You Should Call a Pro
While you can handle tree pruning on your own, there are times when it makes sense to call in a professional:
- Deo suggests calling in a pro when making cuts that are greater than two inches in diameter.
- He also recommends leaving cuts from height up to professional arborists. “Call in a pro for any work that can't easily be done from a homeowner ladder,” he says. “Once you start reaching up for higher and higher parts of the tree, the hazard goes up meaningfully.”