Pruning Trees and Shrubs

Pruning is an important gardening skill, but it can be intimidating at first. The best way to learn to prune is to get out there and do it! This fact sheet will give you the confidence to experiment and have fun while protecting the health of your trees and shrubs. Look over the tree and evaluate its needs. Have clear goals in mind BEFORE making any cuts. Visualize the plant how it will look after the pruning session. Look for the area that jumps out first – where what the plant needs is most obvious. Start by cutting short, small diameter stems. You can always remove more (but you cannot put it back!) Work around the plant in a circle. Frequently step back and reassess, repeating the process as needed. Remove no more than 1/3 of the canopy in a year. Cut the shortest and smallest diameter branches possible. Often, pruning goals can be met with making several small cuts rather than a few large ones. Removing branches larger than ½ the trunk diameter is much more likely to cause decay. Thin and shorten large branches instead of removing them. When pruning diseased trees, clean pruning tools with bleach or rubbing alcohol between each cut and between trees. Do not top trees. Topping is detrimental to aesthetics, safety and tree health. It creates large wounds which are prone to decay, jeopardizing tree health. Trees respond to topping with long, fast growing sprouts which are poorly attached and potentially hazardous. Do not paint tree wounds. Painting tree wounds traps moisture and encourages decay. It is important to use the right tool for the diameter of branch you are cutting. Using the wrong tool can cause crushing or tearing of branches. Make sure your tools are sharp. Hand Pruners or Secateurs Hand tools which are used to cut branches the about ¼ inch diameter or less. Loppers Similar to hand pruners but with longer handles. Use for branches that are too large for hand pruners but smaller than about 1 inch diameter. Pruning Saw A hand held saw that cuts when both pushing and pulling. Use for branches too large for loppers. Always use the 3-point cut with a pruning saw (Figure 1). Locate the branch collar, the swollen area where a tree branch attaches to the trunk. Figure 1 below shows what a branch collar looks like on deciduous and conifer trees. The branch collar contains an energy reserve the plant needs to close wounds, and should not be damaged during pruning. Always make your cut just beyond the branch collar, leaving it intact but not leaving a stub of branch beyond it. (See Figure 1) When using a pruning saw, use the 3-point cut to prevent tearing bark. (See Figure 1) 1. Make a shallow cut on the underside of the branch several inches above the branch collar (Figure 1 - A). 2. Remove the branch, cutting through the top side of the branch a few inches above the first cut (Figure 1- B). After the branch is removed, there should be a stub left. 3. Remove the stub left by the second cut, cutting just beyond the branch collar (Figure 1- C&D). Figure 2: Remove grass in a strip at the edge. Deciduous Conifer Figure 1: Proper Pruning Principles Tree and shrub growth is determined by the highest buds, which are called “dominant”. Dominant buds grow the fastest, suppressing lower buds so they do not grow as much or at all. The buds at the tips of branches dominate those branches and the buds on the highest branches dominate the entire plant. Removing the dominant bud causes sprouting, which can lead to unattractive trees with poor structure and health. Heading Cut (Figure 2) Cutting a branch off at the tip or back to a side stem that is too small to dominate. Generally, if the side stem is less than 1/3 the diameter of the branch you are cutting, it is too small. Heading cuts remove the dominant bud, releasing the lowers buds and causing sprouting. They can be used to shear certain species of shrubs, but should almost never be used on trees. Figure 2: Heading Cut Thinning/Removal Cut (Figure 3) Cutting a branch back to a larger branch. Thinning cuts are a general purpose cut used to remove branches and correct tree structure. This is the cut used most often during a pruning session. Figure 3: Thinning/Removal Cut Reduction Cut (Figure 4) Cutting a branch back to a side stem that is large enough to take over the dominant role. Generally, the side stem should be at least 1/3 the diameter of the cut branch. This cut slows branch growth and suppresses it in relation to the rest of the tree. Because a smaller branch is left with a bud that can become dominant, sprouting is reduced or prevented. This cut should be used sparingly. Figure 4: Reduction Cut Good Tree Structure Trees with one central trunk, called a leader, and smaller side branches are strongest and least likely to break. Figure 4 shows how branches which compete with the leader can be suppressed to allow the central trunk to dominate tree growth. The strongest branching angle is approximately 35 degrees (“ten o’clock” or “two o’clock”); narrower angles are prone to breakage. Branches with narrow angles should be either removed, or shortened and thinned to reduce their weight. Figures 5 and 6 show a tree with no central leader and a narrow branch angle where the two stems meet. The tree is likely to split in this union. Figure 5: The lack of a central leader makes Figure 6: Close-up of a narrow branch angle where this tree structurally week. the two trunks meet. The tree is likely to split here. Pruning Seasons In general, pruning is best done during dormancy (fall/winter). There are exceptions, so research your tree/shrub species for any special instructions. For the best flower display, shrubs that flower on last year’s growth should be pruned right after flowering. Prioritize Branches for Pruning in This Order: 1. Dead, diseased or damaged branches, including stubs from previous pruning jobs. 2. Competing leaders (co-dominant stems); select the straightest, most desirable leader and remove or subordinate the rest. 3. Remove root suckers and branch sprouts. 4. Trim or remove branches for clearance: signs, pedestrian, vehicular. 5. Remove branches that are badly placed, poorly attached, or have narrow branch angles. 6. Lightly shape the tree for balance or desired form. Photo credit: Figures 3-6: Illustrations and photos by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida. .

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