How to Properly Prune Trees and Shrubs

pruningOne of my favorite gardening activities is pruning. I admit that I am addicted to it. I like to observe the way plants respond to pruning with new growth and I love to ‘groom’ my plants.

I should start this pruning post with a disclaimer: I primarily prune to improve the health and vigor of a plant. My pruning style is more natural than others being attracted to native plants so I tend to let things grow to their maximize size and into their natural habit. But I can’t stand branches laying on the ground or rubbing stems or when something becomes too dense for good air circulation or I see potential disease or pest issues.

So what is pruning?

Pruning is simply the removal of selected parts of plants such as stems, branches, flower buds, etc. In my opinion ‘proper pruning’ includes pruning that improves the health and vigor of a plant, promotes flowering, and naturally shapes a plant for visual appeal.  I generally do not encourage pruning to control size (right plant, right place) and I do not advocate shearing woody ornamental shrubs into squares, meatballs, or triangles.

Basically there are four types of pruning.

Shaping that enhances the natural habit. Thinning to create a healthier plant (especially very dense stemmed shrubs) by allowing more air circulation and sunlight into the base as well as removal of rubbing branches and root sucker growth. Reducing which is to control the size when necessary. Rejuvenating to encourage new growth, vigor and flowering of an older shrub by removing about 1/3 of the oldest wood. Sometimes immediate pruning is necessary due to obstruction of a path, the plants have dead, diseased or pest infested parts, or there may be other safety issues such as with large trees.

The most common question I get is when is the right time to prune?

Everyone has heard the “when the pruners are handy” response.  But the answer really depends on what you are pruning. However, these are the seasonal guidelines that I have learned to follow:

Late winter in general is the best time to prune when plants are dormant, especially to rejuvenate or create new growth. It is my favorite time to prune deciduous plants that loose their leaves because I can better see the structure of the plant and find potential issues such as rubbing stems.

In the spring it is best to prune before plants come out of dormancy or ‘bud break’ or even better yet wait until growth has flushed out. Pruning at bud break can stress a plant and actually set back the plants growth and cause other problems as well.  Generally speaking, after flowering is a good time to prune to avoid cutting off potential flower buds. Most spring blooming plants set flower buds on the current summer growth for the following Spring. These plants are referred to as blooming on ‘old wood’ because buds are set on last year’s growth.  Plants that flower after mid-June by and large produce flower buds on ‘new wood’ or the current season’s growth.

Summer is a good time to thin and shape plants as needed. Pruning in late summer (no later than Labor Day in my zone 7 is my general rule) can minimize water sprouts and suckering for plants prone to that reaction.

Pruning in the Fall should be avoided as plants need time to go into dormancy and harden off for winter. Pruning creates the opposite reaction and surges the plant into new succulent growth, which will be killed with frost and potentially harm the plant as well.

Before you prune, know your subject. Identify the plant and know what its natural habit, size, and flower season. You can also observe previous cuts and see what kind of growth reaction occurred from those. Use the proper tools and clean, sanitize and sharpen them regularly. I do not care for anvil pruners as they seem to crush stems to me. I prefer by-pass pruners because they make a cleaner, sharper cut. Also know your goal for pruning and proceed accordingly: to rejuvenate, thin, reduce size, etc. Also when in doubt know when to call an ISA arborist, a certified and licensed tree professional, especially for trickier and bigger jobs.

Beware of bad pruning practices from untrained landscapers.  Topping or the indiscriminate removal of the top portion of a tree creates starvation, stress, invites pest and disease problems, and produces weak limbs and sprouts.  It’s also ugly and will lead to the demise of the tree. Tipping or the removal of only the ends of branches which creates stress on the plant, promotes more growth on the ends of the branches, and invites pest and disease issues also ultimately leading to the demise of the plant. And a practice termed ‘lion-tailing’ where a tree is overly thinned of it’s inner branches and results in a look that is unnatural and the practice is also detrimental to the health of the tree.

I have put together a Pinterest board on pruning for some visual tips. Below are a collection of resources on general as well as specific pruning topics such as roses, hydrangeas, fruit trees, evergreens and more.

Happy Pruning!

Resources for Common Pruning Topics

Pruning (General)

Arbor Day Foundation: Keys to Good Pruning

ISA Trees Are Good: Pruning Trees

University of Minnesota Extension: Pruning Trees and Shrubs

Texas A&M Extension Earth Kind Landscaping: Follow Proper Pruning Techniques

Cornell University Cooperative Extension: An Illustrated Guide to Pruning Ornamental Trees and Shrubs (30 page pdf)

University of Florida Extension: Restore a lions-tailed tree

Virginia Cooperative Extension: A Guide to Pruning / Stop Topping Trees

State-by-State Gardening: Pruning Tips to Salvage an Overgrown Landscape

Pruning Evergreens

Virginia Cooperative Extension: A Guide to Successful Pruning Evergreen Trees

Pruning Roses

University of Illinois: Rose Pruning

NC State University Extension: Pruning Knock Out Roses

UGA Extension: Pruning Roses

Pruning Hydrangeas

UCCE Master Gardeners: When Should I Prune My Hydrangea

Hydrangeas in the North: Getting Blooms in Cold Climates

Virginia Cooperative Extension: Hydrangea Selection, Pruning & Care

Pruning Fruit Trees

NC State Cooperative Extension: Training and Pruning Fruit Trees

Pruning Crape Myrtles

Clemson Univ. Cooperative Extension: Crape Myrtle Pruning

Note: Look for Cooperative Extension resources that are from your state or similar climate for the most accurate timing to prune.

Recommended additional reading: The Pruner’s Bible by Steve Bradley