Angel's trumpet (Brugmansia sp.) grows quickly, so pruning is a necessity. Angel’s trumpet blooms from spring to fall, and you should prune only after it has ceased flowering over the fall and winter months.
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. 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.
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. 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.
When pruning Delphinium grandiorum (Delphinium chinense), 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.
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.
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.)
Knock Out Roses
‘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.
Some selections of English lavender (Lavandula angustifolia) bloom in both summer and fall. Those selections should be pruned after they bloom. 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.
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.
Prune 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.