10 Plants You Should Always Prune in the Fall
"Bloom time is the key to pruning," according to The Grumpy Gardener. 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 over the winter too.
Other plants, however, can't handle fall pruning—such as 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. 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." You can prune some plants in the fall because they will form flower buds on new growth next season, not last year's old growth. Read on for a list of plants you can prune, trim, and shear in the fall, with a few exceptions.
Angel's Trumpet
Angel's trumpet (Brugmansia sp.) grows quickly, so pruning is necessary. Angel's trumpet blooms from spring to fall, and you should only prune after it has ceased flowering over the fall and winter months.
Learn more about angel's trumpet.
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Butterfly Bush
You can clip several butterfly bush species (Buddleia ssp.) in the fall. However, you should only prune Buddleia alternifolia and Buddleia x pikei 'Hever' ('Hever Castle') 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 the ground." Buddleia davidii, on the other hand, should be pruned in late winter to early spring.
Learn more about butterfly bush.
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Chaste Tree
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, [the] plant will send out a second flush of blooms."
Learn more about chaste trees.
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Delphinium
When pruning Delphinium grandiflorum (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 once the blooming season ends in the fall.
Learn more about delphinium.
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Gardenia
Gardenia bursts into fragrant blooms in summer, and the blooming season lasts well into fall with most species. 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.
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Hydrangea
Many hydrangeas do well when pruned in the fall, including 'Annabelle' and 'Limelight' hydrangeas. On the other hand, you should not prune Oakleaf hydrangea in the fall.
Learn more about hydrangea.
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'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.
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Lavender
Some selections of English lavender (Lavandula angustifolia) bloom in summer and fall. You can prune these varieties that bloom in summer and fall after the last flowering.
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.
Learn more about lavender.
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Phlox
According to The Southern Living Garden Book, regarding particular phlox species, including Phlox subulata, "After flowering, you should cut the plant back halfway." This 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.
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Pomegranate
The Southern Living Garden Book recommends pruning pomegranate "as you would for its cousin, the crepe myrtle (Lagerstroemia 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.