Basic Principles of Pruning Woody Plants

Pruning is a great way to keep your plants healthy and looking their best. Pruning removes dead, diseased, or damaged branches from the plant. It also stimulates new growth to fill gaps where there are no leaves on the branch tips. 

This will help with air circulation and sunlight penetration into the plant’s crown, resulting in healthier foliage that produces more flowers or fruit, depending on what type of plant it is.

The most important thing to remember when pruning woody plants is not too much off at one time, which can weaken the tree over time as it doesn’t have enough energy to replace all those branches at once so you want to do it gradually instead of all at once, so you don’t shock your tree.

Pruning is one of the most important cultural practices for maintaining woody plants, including ornamental trees and shrubs, fruits and nuts. It involves both art and science: art in making the pruning cuts properly, and science in knowing how and when to prune for maximum benefits.

There are numerous reasons for pruning. Sometimes you want to train or direct the growth of plants into a particular form or a specified space, like a formal hedge. Or you may want to prune mature plants to control their size and shape, as in the case of fruit trees that are pruned low to the ground to aid picking or hedge plants pruned at a particular height. 

Finally, pruning plays an important role for fruiting plants in improving overall fruit quality, primarily by increasing light penetration into the tree.

Unfortunately, many people approach pruning with a great deal of apprehension. Others view pruning as a chore and give a little forethought to technique as they hastily do the job. However, proper pruning requires a basic understanding of how plants respond to various pruning cuts. The principles and guidelines in this publication will help you master common pruning techniques.

We will cover when it’s appropriate to trim back branches or stems of different heights, which tools should be used for each type of plant, and what kind of cuts are made. We hope you find this article helpful!

Tree Trimming vs. Tree Pruning — What’s the Difference?

If you’re a homeowner who cares for their yard, chances are you’ve considered tree trimming and tree pruning before. Both are excellent services within the landscape industry. The differences are subtle, though. 

Pruning is used to remove unnecessary branches. Trimming, on the other hand, promotes healthy growth. Both services are performed at separate times of the year, using vastly different pieces of equipment to provide a better aesthetic and healthier landscape. Understanding the difference, though, is crucial.

Tree Trimming

Tree trimming helps trees, shrubs, and hedges growth in a healthy manner. Often, commercial clients trim trees to make their property more attractive to prospective clients. A better appearance typically means more visitors.

Professionals generally focus on removing green shoots, which helps encourage healthier growth overall. But, on top of growth, trimming also improves the appearance of the tree itself.

Tree Pruning

Pruning is not just limited to tree maintenance. The term is often associated with the removal of unnecessary branches and sometimes even roots. These branches and roots may be dead and need to be cut away from the tree.

Pruning a tree can have many benefits. The first and most important is keeping the people around it safe. A dead branch can fall from a tree at any time, endangering nearby people, buildings, and power lines. 

Removing dangerous limbs and maintaining a safe tree is always the best course of action. However, depending on the size of the tree and the location of the branches to be pruned, pruning itself can also be very dangerous. 

To ensure your own personal safety, we recommend you let an expert do any pruning you’re not absolutely comfortable and confident in doing.

In some cases, branches grow in the wrong direction. For example, they push towards electrical utility wires or structures. Pruning helps keep unwanted growth in check.

Equipment Used

When it comes to pruning, shears are often the choice tool – hand shears or lopping shears. These shears are typically strong enough to cut through thin branches. For thick branches, a saw may be required. For trimming, shears, trimmers, and saws provide efficient results and healthier overall growth.

Tree growth and structure

There are many reasons why pruning a tree is important. First, pruning a tree can influence in what way the tree grows. With proper pruning, a tree can be made to grow into a certain configuration of limbs and branches that is more ideal for the tree’s structural integrity.

Maintaining the tree’s structure helps to mitigate the risk of broken limbs and falling branches. A properly pruned tree will not compromise branch structures and improper weight distribution that could lead to disaster later in the tree’s life. 

Structural pruning can also greatly improve the general look of the tree. If aesthetics are important to you, proper pruning can make a tree grow in the desired fashion.

When to Prune

Remember, it’s important that any pruning (other than emergency branch removal) be done in late fall or winter, during the dormant season. It’s during this time that the tree is least susceptible to harm that may result from pruning. 

Trees are susceptible to stress just like any other creature, and removing their branches does cause damage to the tree. When the tree is dormant, however, less sap is lost and, since they are dormant as well, insects and fungus are less likely to damage the tree further.

In addition, certain species of trees require more precise timing and different approaches for proper pruning. If you’re ever in doubt, contact a certified arborist instead of risking both the tree’s safety and your own.

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Less is More

It’s also important to remember not to prune too much off of a tree. Generally, you want to prune the smallest amount you possibly can that achieves the desired effect. For example, never prune more than ¼ of the crown of a tree, as this is where most of its leaves are located and consequently where it gets most of its energy. 

You run the risk of fatally damaging the tree if too much is pruned too quickly. Again, a certified arborist is your best bet if you want the job done properly and safely the first time.

Shoot Growth And Apical Dominance

The pruning Process refers to the normally occurring process that changes and reduces the number of neurons, synapses, and axons within the brain and nervous system. Infants are born with a massive number of available nervous synapses that, with growth, age and experience, reduce in number to include useful and needed ones, while the unused disappear with time.

For this reason, it is important to create a mentally and physically stimulating environment for infants and children in order to maximize the neural pathways created before this pruning process begins.

You can partly determine the characteristic shape and size of a woody plant and its response to pruning by the plant’s natural pattern of shoot growth. When a seed germinates and grows, only one growing point exists, the apex or terminal bud. 

When a terminal bud begins growing after being dormant, it leaves a bud scale scar on the branch. You can use the scars to determine the age of a limb or tree by counting the scars. As the new shoot elongates, structures called nodes are formed. A node is an area on the shoot where a leaf is attached. One to three lateral buds are produced at each of these nodes. 

The growth of lateral buds is directed by the terminal bud, which produces a hormone called auxin. Auxin moves downward in the shoot (toward the Earth’s centre) from the shoot apex and inhibits the growth and development of lateral buds. This phenomenon is called apical dominance.

The intensity of apical dominance varies from one plant species to another. Some plants suppress the growth of their lateral buds until the second growing season; others develop both lateral shoots and terminal buds during the first growing season. 

Apical dominance influences the number of shoot-forming lateral buds, the lengths of lateral shoots formed, and the angle at which the shoots emerge from the main limb.

The orientation of a limb or shoot along the main branch has a major influence on growth by its effect on apical dominance. Because auxin moves downward in the shoot toward the Earth’s centre, apical dominance is strongest in vertical or upright shoots or limbs. 

In vertical limbs, vigorous shoot growth occurs near the terminal bud, with lateral shoots becoming more sparse with increasing distance from the apex. On the other hand, the orientation of lateral branches at 45° to 60° angles from the vertical or main shoot reduces the vigor of shoot growth near the apex and increases the number and length of laterals along the limb further from the apex. 

On horizontal limbs, apical dominance is totally lost. Without apical dominance to control their growth, lateral buds on the upper side of horizontal limbs develop into vigorous, upright shoots, called water sprouts. As they develop, water sprouts show very strong apical dominance. Water sprouts are common on the upper surface of flat limbs in fruit trees and are removed by pruning.

General Responses to Pruning

Pruning is an invigorating process. By removing the apex, pruning temporarily destroys apical dominance and stimulates the growth of lateral buds into shoots.

Pruning also reduces the size of the above-ground portion of the plant in relation to the root system. As a result, the undisturbed root system services a smaller number of shoots and buds. As a result, the relative uptake of water and nutrients by the remaining shoots and buds increases, and a flush of growth (regrowth) occurs.

Generally, the more severe the pruning (greater size or number of limbs removed), the greater the resulting regrowth. In essence, the plant is regrowing in an attempt to restore a balance between the top and the root system.

Pruning generally stimulates regrowth near the cut. Vigorous shoot growth will usually occur within 6 to 8 inches of the pruning cut. This is particularly true for vertical limbs that have been pruned. However, regrowth on limbs having a 45° to 60° angle from the vertical will develop farther away from the cut.

Pruning may also indirectly stimulate lateral shoots’ growth by allowing more light to penetrate the plant’s canopy.

Pruning a young plant will stimulate vigorous shoot growth and will delay the development of flowers and fruit. Of course, the length of the delay will depend on the species pruned and the severity of the pruning.

Types of Pruning Cuts

There are two basic types of pruning cuts, heading and thinning. Each results in a different growth response and has specific uses.

Heading removes the terminal portion of shoots or limbs. By removing apical dominance, the heading stimulates regrowth near the cut. It is also the most invigorating type of pruning cut, resulting in thick compact growth and a loss of natural form, as in a formally pruned hedge. 

Sometimes ornamental shrubs along a foundation overgrow their planting space and are rejuvenated by heading to within 12 inches of ground level. Many broadleaf shrubs such as burford holly, ligustrum, abelia and crape myrtle tolerate this type of pruning. Other types of heading are topping, dehorning, hedging and clipping.

On the other hand, Thinning removes an entire shoot or limb from the main branch or lateral to its point of origin. Some shoot tips are left undistributed, so apical dominance is maintained. As a result, new growth occurs at the undisturbed shoot tips while lateral bud development and regrowth is suppressed.

Thinning is generally the least invigorating type of pruning cut and provides a more natural growth form of plants. Important in maintenance pruning, thinning cuts are used to shorten limbs, improve light penetration into plants, and direct the growth of shoots or limbs.

Drop-crotching, a form of thinning used to reduce the size of large trees, involves the removal of a main branch (or leader) by cutting it back to a large, lateral branch. The cut through the main branch is made parallel to the angle of the remaining lateral. 

When removing large tree limbs, a series of three cuts are recommended in order to avoid tearing the bark along with the main truck and severely wounding the tree. One undesirable form of thinning is the bench cut, where a vigorous upright limb is thinned to a horizontal limb 

Vigorous, upright shoot growth, called water sprouts, often result from the “bench” area because of the absence of apical dominance in the horizontal limb. However, such regrowth is weak and often results in an undesirable umbrella-shaped plant. 

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The correct method is to make the thinning cuts to limbs that are similar in angle to the limb being removed but not greater than 45° to 60° from vertical.

Shoots or limbs having narrow-angled crotches are weaker than those having wide crotch angles. As a result, the bark of the adjoining branches becomes tightly compressed or “included,” preventing normal wood development. In addition, winter ice, trapped down in crotches, often causes narrow-angled branches to split.

Healing Response to Pruning

Healing naturally follows pruning or wounding. It starts in the cambium, a thin layer of cells between the wood and bark. Two areas of the cambium, the bark ridge at the junction of two limbs and the branch collar, a ring of slightly raised tissue where the lateral branch joins the main limb, function to close off the wound between the plant and the pruning cut. 

Prune close to the main branch without injuring the bark ridge or branch collar areas for the fastest healing. Leaving a stub will slow healing and invite decay. Wound dressings or pruning paint are cosmetic and do little to promote healing of the pruned area.

Time for Pruning

Time of pruning varies with plant species. Prune at times that best complement the growth characteristics, flowering, and other objectives you desire.

Many woody ornamentals are pruned according to their date of flowering. For example, spring-flowering plants, such as dogwood or forsythia, normally are pruned after they bloom. Pruning spring-flowering shrubs during the dormant season will remove flower buds formed the previous fall. 

Summer-flowering plants generally are pruned during the dormant winter season. If plants are not grown for their flowers, the best time for pruning is during the dormant winter season before new growth begins in the spring. 

Avoid heavy pruning during the late summer and fall because regrowth may occur and make the plants more susceptible to cold injury. Peach trees, for example, should not be pruned from October through January.

Some plants bleed heavily after pruning. Bleeding is unsightly but not usually harmful. Trees subject to bleeding should be pruned in the late spring or early summer when leaves are on the tree. 

Actively growing leaves tend to reduce the amount of bleeding from pruning cuts and allow the cuts to heal more quickly. Plants that bleed readily include willows, birches, maples, beeches and dogwoods.

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