A Complete Guide to Pruning and Trimming Trees

by Chris Lambton

As leaves fall from the trees each autumn, branches formerly covered in a canopy of dense foliage come out of hiding. Although many gardeners would rather never deal with the falling mess of leaves, I relish this time as an opportunity to inspect each tree canopy. It's now that I carefully make note of any branches I may need to remove from my trees. Taking advantage of these dormant months gives me time to develop a plan for pruning and trimming trees in my landscaping.

When and How to Prune Tree Limbs Properly

In this article, you'll learn:

Why is it Important to Prune Trees?

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Tree limbs are pruned for multiple reasons, all of which result in a better looking and better performing tree. Although trees do grow quite naturally without pruning, this routine landscape maintenance allows your trees to reach their full potential and live a long life. But before you can learn how to trim a tree properly, you need to know why you should trim a tree.

Pruning for plant health focuses on removing dead, dying and diseased branches, branches that rub together and any branch stubs so the entire tree continues to grow in a healthy way. Opening up the canopy to let light and air filter throughout the entire tree allows for increased foliage while decreasing the risk of disease. At the ground level, suckers and water sprouts weaken wood and steal nutrients from the main tree. By helping a tree establish one main tree and a dominant leader, you create a strong tree that's ultimately able to withstand winter storms and high winds.

Landscape maintenance and appearance pruning combine to create the ideal plant you envision. By pruning and trimming trees in specific ways, you can encourage fruiting and flowering, shape plants into specific forms and control plant size.

Safety concerns are not often considered, but they're definitely a good reason to prune your trees. Trimming the trees in your yard creates a safe environment for your family and friends. Well-pruned trees are stronger and healthier. Dead branches, diseased trees and weak limbs are all a danger to people and property. When pruning trees, take a moment to assess if tree branches are becoming too close to safety lights, electrical lines or are blocking traffic views.

Depending on where you live, it is also important to prune trees to thin out branches and dead limbs before hurricane seasons. Too much foliage can result in trees being top heavy and falling over easier in storms, and falling branches may damage a house or plants below.

Proper Way to Prune a Tree Limb

When thinning, reducing and shaping branches and limbs small enough to cut with hand tools, keep in mind that your cuts are going to encourage new growth. Cut limbs ¼ inch above a bud that faces the outside of the plant. This will be the direction of the new growth. Keep your cuts at a 45-degree angle to prevent water damage and disease.

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Pruning Thick Tree Branches

Properly pruned tree branches form a callus where the removed branch once was. This callus is essential to the health of the tree. Most tree branches that are cut back to the trunk or a main branch will require three cuts to prevent damage to the bark. The first two cuts remove the weight from the tree branch, and the final cut is designed for the best callus growth.

Step one: Travel approximately 18 inches up the underside of the branch you are removing.

This is the perfect location for your first cut. Cut up about halfway through the branch.

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Step two: Move to the top side of the branch.

Choose a location an inch further out from your first cut. Carefully cut down until the branch breaks free.

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Step three: Find the branch collar on your trunk.

This is the stem tissue around the base of the branch. With most trees, you'll see a slight swelling and rougher bark in this area. You want to make your final cut just to the outside of this collar, but without leaving a stub. Make a complete cut with a 45-degree angle kicking out from the base of the tree. This prevents water damage and encourages the quick formation of the callus.

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Tree Pruning Tips

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Pruning trees may seem like a large project – and it can be. I recommend leaving large, established shade trees to qualified arborists and tree care professionals. They have the appropriate equipment and training to remove large branches safely. Ornamental and fruit trees are the perfect place to start learning how to prune a tree. Most are easily accessible and require simple tools.

Start Pruning Trees Early On

A proactive homeowner begins pruning as soon as a tree is planted. Diseased, dead and broken branches should be removed right away. Pruning for shape isn't necessary until the first winter after planting. Regular pruning throughout the life of a tree reduces the amount of work necessary and the stress on the tree. Pruning a tree a little each year creates a strong and beautiful tree from the very beginning.

When is the Best Time of Year to Prune Trees?

There is never a bad time to remove dead, damaged or diseased branches. But most trees benefit from pruning in mid to late winter. Pruning during dormancy encourages new growth as soon as the weather begins to warm. The lack of leaves after autumn allows you to easily identify branches and limbs requiring removal.

Be aware that some trees can bleed sap when pruned during late winter. For example, pruning maple trees in winter is ideal but can result in bleeding. Don't worry – the sap will stop flowing as soon as the tree begins to put on leaves. It isn't dangerous and it won't harm your tree.

Although I like to make my pruning plan in the fall, I always wait a few months to before I start to actually prune. Pruning trees in fall can introduce disease. In the event of a warm fall, it could even encourage new growth which will be damaged when temperatures drop.

Pruning trees in summer isn't a popular option, but sometimes can be beneficial if performed with caution. Experienced gardeners use summer pruning to direct growth by slowing down the development of a tree or branch. The best timing for this form of pruning is just after the seasonal growth has reached its peak. By removing the total leaf surface of the plant, you reduce the amount of nutrients sent to the roots and the overall growth of the tree.

Now that we've established when the best time of the year is to prune trees, let's talk about flowering trees. They don't exactly follow the rules. Flowering trees fall into two categories: early bloomers and late bloomers.

Early Blooming Trees

Early blooming trees set buds on last year's growth. For example, a tree blooming early in 2018 is blooming on growth from 2017. If you prune over the winter, your tree won't bloom. Instead, prune right after the tree finishes blooming. Early blooming trees include:

  • Apricot
  • Chokecherry
  • Ornamental Cherry
  • Flowering Plum
  • Magnolia

Late Blooming Trees

Trees that bloom in late spring to early summer set buds on this year's new growth. For example, a tree blooming in June of 2018 is blooming on growth from 2018. These trees should be pruned in early spring for the best bloom:

  • Catalpa
  • Dogwood
  • American smoke tree
  • Hawthorn
  • Japanese tree lilac

Tree Pruning Methods

There are many ways to improve both the health and the shape of a tree. The goal of each is to create a tree with good light and air circulation, attractive qualities and strength. The four most popular tree pruning methods for general pruning are crown thinning, crown raising, crown reduction and crown cleaning. You may notice that each pruning method involves the crown of the tree. That's because the crown of the tree is essential for producing leaves for photosynthesis. Without a strong and healthy crown, the rest of the tree will weaken over time.

Crown Thinning

Thinning the crown involves trimming a tree to remove specific live branches to reduce the overall density of a tree. Thinning is the most common pruning performed on mature trees. It increases sunlight penetration and air circulation. It can also reduce stress on selected limbs from gravity, wind, ice or snow.

Because the goal is not to change the size or shape of the tree, thinning should be consistent throughout the tree. You should only remove 10 to 20 percent of the tree branches from the edge of the canopy. Large trees benefit from removing end portions of limbs between 1 to 4 inches in diameter. Small ornamental landscape trees and fruit trees can be thinned by removing smaller limbs between ¼ to ½ inch thick. You should trim trees for crown thinning so that the tree still looks completely unpruned.

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Crown Raising

Crown raising lifts the bottom edge of tree limbs up to clear for traffic, buildings or a view. This tree pruning method should be performed gradually over a long period of time. Removing too many lower branches all at once can result in a weak tree. Remove only a few limbs less than four inches in diameter when pruning every year. I like to take a few steps back periodically and look at the overall balance of the tree. The live crown on deciduous trees should make up 60 percent of the tree. If the trunk begins to go over 40 percent, the tree could become weakened. Most conifers can be balanced at a 50 percent crown and 50 percent trunk ration and still remain strong and healthy.

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Crown Reduction

Crown reduction is a tree pruning method generally used on older, more mature trees. It can help strengthen the tree and encourage new growth. Crown reduction removes a tree branch back to a growing lateral branch. When the growing season begins in the spring, this lateral branch will become part of the new tree crown. I consider this method a gentler alternative to tree topping. There are smaller cuts, less of the crown is removed and plenty of old growth remains for structure. While crown thinning is performed to reduce limbs and foliage, the goal of crown reduction is to remove old growth while encouraging new.

Crown Cleaning

Crown cleaning is the removal of dead, diseased and broken branches when trimming a tree. It can be performed at any time and should be included as a part of crown thinning, raising and reduction. Cleaning the tree crown strengthens the overall tree, and prevents future damage to both the tree and surrounding property while increasing the overall safety of your landscaping.

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Best Tools for Pruning Trees

Now that you know how to prune trees, let's look at how to make it as easy as possible. Sharp, quality tree trimming tools can turn a dreaded chore into a quick task. I always keep these tools handy for all my garden pruning and trimming needs:

  • PowerGear2™ Pruner with ergonomic handles and patented gear technology that gives up to 3X more power for cutting stems and branches up to ¾" thick
  • PowerGear™ 2 Lopper for extended reach and optimized power to cut through the middle branches up to 2" in diameter, where you need the most leverage
  • Power Tooth® Softgrip® Saw for removing large limbs and branches with clean, quick cuts – the unique teeth design cuts through wood quickly and smoothly
  • Extendable Pole Saw and Pruner to reach branches up to 16 feet away – a special low-friction coating allows you to easily cut branches as thick as 1 1/4 inch
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