How to Trim Landscaping Trees

How to Trim Landscaping Trees

Aug 31, 2017

One of the most valuable assets in every home’s landscape is the trees. Trees come in all shapes, sizes and species. They add enormous aesthetic beauty to the landscape as well as contributing to environmental well-being. Trees also significantly increase property value. They can become valuable assets to any property provided they are well cared for.

Three major factors contribute to the well-being of landscape trees. Selecting the right type of landscape tree for the correct location, then carefully planting it and finally maintaining it for optimal growth, is paramount to its life-long value. So is proper pruning. Pruning a tree is a critical part of ongoing landscape maintenance. Correctly done, a well-trimmed tree will be far healthier and stronger than a neglected plant.

Knowing how to prune trees properly is something every professional arborist prides themselves in. It's also important that homeowners know how to trim a tree. There's a process to correctly pruning trees. In fact, it's considered an art form in ornamental gardening and topiary displays. These green-thumb artists are masters who truly know how to trim landscaping trees. Ordinary groundskeepers and home gardeners can easily adapt their techniques and tree treatments.

Tree Trimming Basics

person with gloves pruning a tree limb

Pruning, by definition, means cutting branches or diseased leaves and other foliage off trees and other plants, which allows you to direct or control the growth of the plant, ensure structural strength of the main branches and to increase the plant or tree’s number of flowers or fruit.

Simply put, good pruning lets a tree supply additional energy to productive parts like roots, leaves, flowers and fruits. When you properly trim a tree, it prevents wasting water and nutrients on unproductive growth or in repairing diseased or damaged areas. There are some common-sense dos and don’ts to tree trimming.

Pruning or trimming a tree is a learned skill. However, more trees are killed or severely damaged each year by improper pruning rather than by pests or disease. Pruning trees is not a matter of attacking them with shears or a saw. There’s a process to follow as well as knowing when you should prune a tree. Trimming during the wrong phase of a tree’s growth cycle can be as devastating as making the wrong cuts in the wrong places.

There is a right way and a right time to trim landscaping trees. A rule about timing is that trees need to be pruned when it’s convenient for them, not when it’s convenient for the homeowner. There are also rules for making precise cuts and proper shaping. Fortunately, the tricks and timing are easy to learn and apply, as is knowing how to use tree trimming tools properly. Safely pruning a tree is important, as sharp tools can be just as dangerous as working at height.

Why Trees Need Pruning

Carefully pruned landscape trees are structurally stronger and healthier. They’re also more beautiful and valuable. Beyond protecting an investment, landscape managers know when it’s best to prune trees and what factors to take into account when making their first cuts. Professional arborists consider:

  • What branches are dead, dying, diseased or defective
  • Where branches are weak or cross over
  • Limbs that have been storm-damaged
  • When tree growth is extending into utility lines
  • Providing clearance for pedestrian or vehicle passage
  • Removing tree limbs and foliage that compromise buildings or sightlines
  • Allowing sunlight to penetrate the tree canopy more effectively
  • Promoting blossom, fruit and nut production
  • Overall enhancement of tree performance

Professional arborists follow a definite plan. They know what’s best for each species including the exact time of year to make cuts. Proficient tree trimmers consider the purpose of why they’re pruning. That will vary depending on the tree’s age and location. They follow a certain pruning order which greatly reduces the number of cuts and the amount of time spent on an exacting job.

Three-Step Tree Trimming Process

Primarily, tree pruners follow a three-step process that makes them efficient and economical. These steps are:

  • Step 1: First, remove and discard all dead and damaged limbs. That includes diseased wood and foliage. Remove problem limbs at their point of origin or back to a strong and healthy branch. This opens the canopy and lets light penetrate. Often, all that’s required is the first step.
  • Step 2: Second, train the tree. This is about promoting growth in a pre-determined direction. It might include rectifying open areas caused by storm damage or keeping it within bounds of a confined area. Professional arborists take into account the tree’s natural growth characteristics and work with nature, not against it.
  • Step 3: Third, make corrective cuts to undesirable branches that are competing with limbs that contribute to the overall tree plan. This might be weak points at crotches or secondary leaders that have developed. A tree may need corrective cuts to eliminate limbs at obtuse angles that detract from the tree’s desired balance.

After each pruning step, knowledgeable tree trimmers stand back and view their work. They’re careful about not removing too much material at one time or in one year. They look at the big picture and assess what’s best for the tree’s long-term survival. They might see that corrective cuts may be needed but wait for the following year to avoid stressing the tree and doing more harm than good.

What to Prune from a Landscape Tree

a sunny afternoon in the garden

Pruning a tree encompasses more than simply sawing off branches. Trimming is a calculated and planned process. There are many factors to consider as well as industry terminology to appreciate. Knowing what to trim from a landscape tree takes experience, but the principles are quite straightforward. Some things professional arborists know about are:

  • Tree species including softwood evergreens and hardwood deciduous trees
  • Seasonal changes and growth cycle periods
  • Random and whorl-branching patterns
  • Terminal, lateral and latent buds
  • Suckers that grow from the roots
  • Sagging and drooping limbs
  • Watersprouts that appear on branches
  • Crossed or rubbing limbs
  • Pinching, heading, thinning and stub cuts
  • Feeder roots that need protecting
  • Flush cuts at branch collars
  • Topping vs. thinning
  • Training young trees
  • The 45-degree, 1/3 and 1/4 rules

All this tree-trimming jargon might sound complicated and beyond the grasp of a homeowner or part-time landscaper. But it's not. Learning pruning principles is basic, and there are proven points to know and practice. Here's a look at these core principles.

Tree Trimming Seasons

man trimming a tree

It’s important to know when you should prune a tree. Pruning begins as soon as a tree is planted. Careful attention continues throughout its entire life, but it requires trimming more in the first few years than when the tree reaches maturity. If you practice proper pruning techniques early on, the tree’s health and appearance will improve tremendously compared to correcting an older tree that’s been improperly looked after.

The best time to prune a tree is in its dormant season. For most of the country, that’s in the winter when a tree conserves energy for its next growth cycle. Deep winter is not necessarily ideal, though. Frost and excessive freezing can affect fresh cuts, so it’s best to wait till the weather starts changing but before new growth occurs. Once new growth starts, the shock from pruning can slow branch and foliage production as well as natural root development.

If you need to do pruning in the spring or summer, it's wise to wait until a deciduous tree has blossomed but before it bears fruit. There is a short window where the shock is minimal, and there's limited adverse effect from trimming. It's similar with conifers. Prune them in the late winter as well and avoid any pruning once new cones start to develop.

Summer trimming should only happen when truly necessary. During summer months, a tree is making best use of photosynthesis through sunlight and building sap for energy. Summer cutting causes excessive sap bleeding and makes healing a fresh wound difficult for the tree. It also sets the roots into protection mode rather than sourcing water to support new life.

Pruning in the fall is a bad idea. Damage from cutting may not have time to heal. This leaves the tree vulnerable to cold damage and frost burn on exposed wood. Early and mid-winter trimming is not advised for the same reason. Only prune in the deep winter if the tree is damaged and intervention to prevent further loss is necessary.

Making Pruning Cuts

Although there are many variables that go into tree trimming, there are some hard and fast rules when it comes to making actual pruning cuts. They’re called the 45-degree rules, the 1/3 rules and the 1/4 rules. Here is how they apply.

45-Degree Rules: The 45-degree rules state that all pruning cuts should be made at a 45-degree angle to the lateral line of the limb being severed. It applies whether a tip is being cut off just ahead of a bud or if it’s a main scaffold branch being removed from a large trunk. 45-degrees give the perfect exposure for the wood to heal. Any less than 45-degrees has insufficient wood exposure and greater than 45-degrees exposes too much raw material to heal quickly.

The 45-degree rules also apply when choosing what branches should be removed from a tree. Branches that grow out vertically from a tree trunk at less than a 45-degree angle are not as structurally stable or as strong as branches that emerge at a 60 or 90-degree angle. Limbs that extend upwards can compete with the tree's primary leader or vertical upright.

1/3 Rules: The 1/3 rules say that side branches should be at least 1/3 smaller in diameter than the tree trunk. Large branches take up great amounts of energy and give little back to the tree’s overall growth. It’s best to trim them off. The 1/3 rule also carries on to assessing what limbs will perform best. Branches should be encouraged when they’re 1/3 off vertical. The best branches shoot up at the “ten and two o’clock” positions. Don’t prune branches up from the ground more than 1/3 of the tree’s height.

1/4 Rules: Now to apply the 1/4 rules. First, never remove more than 1/4 of a tree's canopy in one year. That's a recipe for shock, and the tree might not survive. Second, it's essential to prune a branch 1/4 inch ahead of the bud you're trying to encourage as new growth. Any less than 1/4 inch and there won't be enough wood to protect the bud. It will dry out and die. Any more than 1/4 inch and the old wood will decay and invite fungal growth and parasites.

The 3-Part Cut

There's another fundamental principle to tree pruning that requires a formula. It's called the 3-part cut. This is always used when de-limbing a large branch that has significant weight and has the potential to tear away bark during cutting. This is a proven technique and vital to know when working with larger trees and big branches. As a rule-of-thumb, it's used for branches over 1 ½ inches in diameter.

The 3-part cut is accomplished by first making an under-cut on the limb about 6-12 inches from the trunk or intersecting branch. This should extend halfway through the branch. Next, make a similar cut outward from the first cut, only do this from the top downward. The second over-cut should be around 2 inches ahead of the first cut. This will cause the branch to safely snap off without tearing the bark back into the branch collar. Finally, make a 45-degree finishing cut about 1/4 inch from the branch collar.

The 3-part cut is universally accepted as a sign of a good tree trimming job. It’s important to use sharp tools whether it’s a set of shears for a small job or a saw for a big trimming task. These leave the cut smooth and easy for the tree to heal.

Treating the cut is a controversial matter. It used to be standard pruning practice to coat cut ends to promote healing, but professional arborists no longer follow this reasoning. Studies conclusively show there's no benefit to treating pruning cuts. Provided the tree is otherwise healthy, and trimming is done when it's best for the plant, nature will quickly heal a cut end in no time.

Topping vs. Thinning

The worst type of trimming you can do to a tree is topping it. It's also called "dehorning." That means cutting off the crown or main leader. This will instantly put a tree into major shock, and it might not survive. Topping forces a tree to attempt replacing its leader or primary top spike. That significantly alters the structure and normal growth pattern.

light shining through a canopy

Thinning is the proper way to go about pruning a tree to decrease its overall size including height. By thinning a tree no more than ¼ of its overall mass, the tree will spend energy in replacing the inner foliage and branches rather than extending upward. Trees are naturally programmed to seek light, not obtain height. Proper pruning simply helps Mother Nature.

Tree Trimming Tools

Most homeowners and gardeners only require basic tools for most tree trimming tasks. They're not expensive and easy to source. Pruning shears and serrated trimming saws are the most popular items followed by lopping shears and pole pruners. Gas or electric rotary cutters and chainsaws are also used, but these are dangerous tools and best left to trained professionals.

Working at height is another serious safety issue. It’s one thing to work from a stable ladder. It’s quite another to start climbing branches armed with a running saw. For any extensive, off-ground tree trimming job, contact a professional tree company that has the right tools including aerial lifts.

Prune With Us

The best way to achieve the best pruning results is to start with the right trees. For three decades, Garden Goods Direct has been supplying gardening knowledge and healthy, high-quality trees and shrubs from our nursery to the nation. We’re proud to be your go-to source for all your gardening and landscape needs!

To get started on your own, shop our selection now for a variety of trees and lawn care products.