Pruning: Dos and Don’ts

by Elizabeth McCoy · Published December 11, 2024 · Updated December 17, 2024

Master Gardener Harry Fahl demonstrates pruning techniques at the Williamsburg Botanical Garden in February 2019.

Pruning woody shrubs is both art and science. Selecting which branches to leave and which to remove allows a gardener to train a woody plant into a pleasing, balanced shape that fits the available space. Some gardeners use pruning techniques to create neatly trimmed topiary, elegant hedges, or espaliered fruit trees. Gardeners may also prune roots and branches and remove leaves and buds to train trees to live as bonsai in shallow containers. Woody plants are extremely adaptable and respond in predictable ways to well-timed pruning.

Gardeners may also choose to let selected trees and shrubs grow naturally, with little or no pruning. When there is space for the plant to grow into its potential, and the plant remains healthy and undamaged, its natural growth form may be preferable. Gardeners may carefully prune some woody plants, like hedges or foundation plantings, while allowing others to grow naturally. Gardeners who plant fruit trees will find that they can increase and improve their fruit production through strategic pruning and training each winter. Pruning is something that every gardener can learn with a bit of practice.

Chastetree, Vitex agnus-castus, responds well to regular, annual pruning in late winter to increase its summer blooms.

There are a few basic principles to keep in mind for success with pruning:

Do:

Use the proper tools for the job and keep those tools sharp and clean. Basic equipment includes hand bypass pruners, or secateurs; loppers, and pruning saws. Choose the right tool for the size and weight of the branch you are pruning.

Protect yourself from injury with gloves, long sleeves, and safety glasses. Enlist a helper to help support larger, heavier limbs you may be removing. Hire an arborist who has specialized equipment for jobs with heavy tree limbs, or for work higher up than you can safely reach.

Clean and sanitize blades after removing diseased wood, and before moving from one plant to another. Lysol spray or an alcohol wipe is all that is needed to prevent the spread of pathogens.

Prune away dead, damaged, or diseased wood as soon as possible, at any time of year. Pruning away damaged or diseased wood limits the opportunity for the rest of the tree or shrub to be impacted by disease. Make the cut below the area that is diseased or damaged, to just above a lateral bud in the healthy wood. Keep in mind that new growth will be in the direction that lateral bud is pointing.

Inspect trees and shrubs for crossed and rubbing branches once their leaves have fallen. Choose a branch to keep and a branch to remove when two or more branches are rubbing against each other. Remove any branches growing back into the shrub, towards the trunk, so the shrub doesn’t become congested.

Remove waterspouts growing vertically from a branch, and not outwards at an appropriate angle in line with other branches. Remove suckers emerging around the trunk of the tree or shrub, unless you want the plant to develop into a multi-stemmed shrub.

Try to complete winter pruning before the dogwood blossoms begin to open. March 14, 2017

Know how the pruning cuts you make will affect future growth:

Cut a branch all the way back to its beginning at the trunk or another branch when you want to thin out the tree.
Cut back to a lateral bud to encourage new growth in the direction that bud is pointing.
Pruning out the growth tip at the end of a branch stimulates the lateral buds along its length to begin growing into lateral branches. This helps increase flower and fruit production.
Cutting (heading back) a major branch, as some people do with crape myrtles, will result in lots of new, twiggy growth around the cut. This technique is called ‘pollarding’ and can weaken the tree and allow bacteria and insects to attack the open cut. It will not increase the overall number or quality of flowers the following year.
Never remove a tree’s leader without selecting and training another leader to replace it so the tree continues to gain height and keep its shape.

Prune and train most trees and shrubs while they are dormant in winter. Prune spring flowering trees and shrubs, like Azaleas, after they finish blooming in mid to late spring. Avoid pruning in late summer or fall because new wood may not harden off before winter.

Do rejuvenate older, overgrown multi-stemmed shrubs, like Hydrangeas or Forsythias, by removing up to 1/3 of older stems each year. This is called ‘coppicing.’ Cut the oldest and least productive stems all the way back to the ground to encourage new growth. The shrub should be completely rejuvenated after three years of consistent rejuvenation pruning.

Rejuvenate older shrubs that have grown too large for their space by removing up to 1/3 of their branch length each year. Don’t cut too far into the shrub, but only make heading or thinning cuts in the outer part of the shrub where leaves are already actively growing.

Do remove vines and competing seedling trees from around desirable trees and shrubs by cutting them back to the ground. Vines and seedlings compete for resources, including light, nutrients, and water. They can damage your desirable landscape plants and make them less attractive.

Propagate clones of favorite trees and shrubs by planting 6”-8” pieces of pruned branches in moist potting soil, sand or vermiculite as hardwood cuttings. Plant them so that 2/3 of the cutting is in the soil and 1/3 is visible. Use only woody material that grew during the previous summer, usually the tips of branches or new lateral branches. Allow the cuttings to grow roots over the next several months in moist, but not wet soil. They are alive if leaves open in spring. Plant several cuttings from the same plant because all of them likely won’t root. Transplant the cuttings into larger pots or into the ground once their roots are several inches long, usually six months to a year after striking the cutting.

Consider mature size when planting new trees and shrubs. Choose plants that won’t grow too large for the available space to reduce the need for future pruning to control their height and spread.

Mountain Laurel, and other spring blooming shrubs, are already covered with buds in winter. Wait until after they bloom to perform routine pruning and thinning.

Don’t:

Don’t use dull blades because they will crush and damage plant tissue around the cut. Keep blades sharp with a sharpening stone.

Don’t injure yourself by using a tool with a blade too small to easily make a cut. Choose the proper tool for the job.

Don’t use a tool that is too small to make a clean cut. Use a pruning saw to remove branches more than 1” in diameter. Use the undercut method of three pruning cuts to avoid damaging the branch collar or tearing the tree’s bark.

Don’t spread bacteria or disease with dirty blades. Disinfect blades frequently and always after cutting away diseased wood. Spray the blades with Lysol or wipe with an alcohol wipe.

Don’ damage the branch collar or bark ridge at the base of each branch where it joins the tree. Cut just beyond the branch collar to speed healing of the pruning wound

Don’t paint over pruning wounds with any sort of sealant as this can encourage disease. Allow the tree to heal the wound in its own way.

Don’t leave trimmings lying around the tree. Collect them in a bag or on a tarp as you work to dispose of them later. Bag diseased branches and put them in the garbage to limit the spread of disease.

Don’t prune conifers unless you need to correct a problem. Allow conifers to grow in their natural form. Remove broken, dead or diseased branches as soon as you notice them.

Don’t prune conifer branches further back than needles/scales are already actively growing. Bare, inactive branches in the center of the tree won’t regenerate with new ‘leafy’ green growth. The center, terminal bud in a ‘whorl’ of buds will extend the branch while the ones around the center will grow into new lateral branches. Some gardeners break or cut some of the terminal buds in half in mid-spring to keep the tree more compact.

Don’t try to reduce the size of an overgrown shrub all at once. Spread the job out over several years to limit the shock to the tree or shrub.