How and When to Prune Flowering Shrubs (2024)

FAQs

How and When to Prune Flowering Shrubs? ›

For shrubs that bloom in summer or fall on the current year's growth, such as beautyberry (Callicarpa dichotoma), prune in late winter or early spring. For shrubs that bloom in spring on last year's growth (e.g., Forsythia), prune after their blooms begin to die.

Pruning at the wrong time can make you miss next year's flowers. The rule of thumb is to prune spring flowering shrubs, like azaleas and forsythia, after they bloom. Prune summer or fall flowering shrubs, like roses and crepe myrtles, in late winter or early spring.

A rough rule of thumb is to prune spring-blooming shrubs soon after they finish flowering because most bloom on old wood, while those that bloom in summer and fall usually bloom on new wood and can be pruned in late winter or very early spring.

Follow the 1/3 rule

When making pruning decisions, keep in mind that you can safely remove up to one-third of the plant's growth at any one time. There may be times when you prune more, such as when you are rejuvenating an overgrown shrub, but generally speaking, the “one-third rule” is the best guideline to follow.

Do not prune deciduous shrubs in late summer. Pruning shrubs in August or early September may encourage a late flush of growth. This new growth may not harden sufficiently before the arrival of cold weather and be susceptible to winter injury.

However, you can prune shrubs year-round. Summer is as good a time as any as long as you pay attention to the particular needs of the species and keep your landscape goals in mind. Sometimes, weather or other priorities make pruning challenging during the winter. Not to worry.

After “how?", the second most-asked question we get about pruning is “when?” (Or, "Can I prune this now?") The rule of thumb is to prune immediately after bloom for flowering shrubs, in late winter or early spring for non-blooming shrubs (particularly for heavy pruning), and not after mid-August for any shrubs.

When the sap is flowing

Sap is the lifeblood of a plant, so if you make a cut when it's coursing through the stem of a tree or shrub (early spring for many plants), you're essentially opening a wound. This wound can keep bleeding, sucking the life out of a branch or even the entire plant.

Prune back stems to just above a fat bud — called a heading cut — in fall, late winter or spring. These plants have conical-shaped flower heads. I recommend leaving the dry, tan flower heads on the plant to provide some winter interest in your landscape, so I wait to prune these until late winter or spring.

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Steps to Pruning Overgrown Shrubs

Each year, you remove 1/3 of the plant. After three to four years, you have a new, healthy shrub. Identify the oldest and least productive branches for removal. Cut 1/3 of the plant back to the ground or at the branch collar.

Any time you prune, make proper cuts so you won't damage your plant. All cuts should be made on the branch side of the stem collar, which grows out from the stem at the base of the branch. This protects the stem and other branches that might be growing, and allows the tree to heal more effectively.

In reality, snipping the tips of branches (stubbing out) is one of the worst pruning mistakes you can make. Pruning stimulates the plant to grow, so when you snip the tip of one branch, four to six new branches take its place.

Spring flowering shrubs (those that bloom before mid-June) should be pruned after flowering. Their flower buds develop during the previous growing season on “old wood." If pruned too early, you will remove the flower buds.

Pruning During The Flowering Stage

It is important to remove damaged or dying leaves and buds from the plant so the healthy leaves can do their job. Many cultivators choose to trim the leaves from the plants for only the first two weeks of the flowering stage to allow for appropriate bud maturation.