10 Plants You Should Always Prune in the Fall
What’s the deal with pruning? According to The Grumpy Gardener, when it comes to pruning, “Bloom time is the key.” For some plants, careful pruning trims away old growth to make room for the new and to encourage flowering. Pruning can make plants hardier and help them overwinter too. Other plants, however, can’t handle a fall pruning (we’re looking at you, azalea, viburnum, loropetalum, and lilac.) If you prune a spring-blooming tree or shrub after its flower buds have formed, you’ll be lopping away any opportunity for a spring showing. Read on for a list of plants that you can prune in the fall, with a few caveats. These are the plants that you can usually trim and shear in the fall months. These autumn pruners may even encourage you to skip your post-Thanksgiving nap. It’s ok to clip them in the fall because these plants form flower buds on new growth next season, not the old growth of last year.
When in doubt, always remember this advice from The Grumpy Gardener, “The best time to prune a flowering tree, shrub, or vine is after it finishes blooming. Prune summer-flowering woody plants in late fall or winter. Ignore this rule and your plant probably won't bloom the next year and you'll get all pouty and irritated.” On the other hand, also be sure to brush up on our list of plants you should never prune in the fall. (And for the Southern-favorite crepe myrtle, we have an entire pruning how-to for you.)
Here's When to Prune These Plants
Several butterfly bush species (Buddleia sp.) can also be clipped in the fall. Buddleia alternifolia and Buddleia x pikei 'Hever' ('Hever Castle') should be pruned after they bloom, as they flower on new growth. According to The Southern Living Garden Book, when you prune butterfly bush, you should “remove some of the plant’s oldest wood down to within a few inches of ground.” Buddleia davidii, on the other hand, should be pruned in late winter to early spring.
Learn more about butterfly bush.
Chaste trees (Vitex agnus-castus) bloom on new growth, so even though it’s encouraged to prune them in late winter, you could also prune them as early as late fall. According to The Southern Living Garden Book, when you prune chaste trees, you should be “removing twiggy growth and crowded branches. If you remove spent flowers before seeds form, plant will send out a second flush of blooms.”
Learn more about chaste tree.
When pruning Delphinium grandiorum (Delphinium chinense), according to The Southern Living Garden Book, “After blooms fade, cut stalks nearly to the ground, leaving foliage at the bottom. Fertilize again, and you may get a second bloom.” You can cut back the leaves again once the blooming season ends in the fall.
Learn more about delphinium.
Gardenia bursts into fragrant bloom in summer and with most species, the blooming season lasts well into fall. As the blooming season ends and flowers begin to fade, you should prune gardenia plants to remove any drooping, leggy branches and past-their-prime flowers.
Learn more about gardenia.
Many hydrangeas do well when pruned in the fall, including ‘Annabelle’ and ‘Limelight’ hydrangeas. (Oakleaf hydrangea, on the other hand, should not be pruned in fall.)
Learn more about hydrangea.
‘Knock Out’ Rose
‘Knock Out’ roses bloom on new growth, and you can usually prune anytime except for late summer and early fall. Any other time of year—late fall included—you can take advantage of a post-blooming resting period by cutting them back by one-third.
Learn more about ‘Knock Out’ roses.
Some selections of English lavender (Lavandula angustifolia) bloom in both summer and fall. Those selections should be pruned after they bloom. According to The Southern Living Garden Book, “To keep plants neat and compact, shear back by one-third to one-half every year just after bloom.” Just ensure that the plant has time to ready itself before winter sets in.
Learn more about lavender.
According to The Southern Living Garden Book, when it comes particular species of phlox, including Phlox subulata, “After flowering, you should cut the plant back halfway.” This particular species of phlox “blooms in late spring or early summer, bearing inches flowers in colors including white, pale to deep shades of pink, and lavender-blue.”
Learn more about phlox.
The Southern Living Garden Book recommends pruning pomegranate “as you would for its cousin, the crepe myrtle (Lagerstromia sp.). Select three to five shoots to become the main trunks, and remove all others at the ground. In late winter, open up the plant by pruning away twiggy growth, dead branches, and any branches growing inward toward the center.”
Learn more about pomegranate.