Key Points
Prune shrubs based on bloom time, cold tolerance, and variety—check what’s best for each type.Cut back new wood hydrangeas in fall, but wait until after blooming to prune old wood ones.Remove dead or damaged branches anytime to keep shrubs healthy and shapely.
Pruning isn’t required for all shrubs, but for many of them it’s crucial to helping them thrive. Pruning helps maintain good shape and form, and stimulates new growth. But the best time for pruning can vary, depending on the shrub and the season. But which shrubs are best pruned in the spring, and which ones should wait until fall?
We talked with some garden experts about which shrubs should be pruned in the fall, and other tips for their care.
Meet the Expert
Shane Hemphill is a landscape design expert and co-founder of Art of the Yard, a Denver company that specializes in water features and garden landscapes.
Laura Janney is a gardening expert, botanical stylist, and CEO of the Inspired Garden Masterclass.
Hydrangeas (New Wood)
Whether or not to prune hydrangeas in the fall depends entirely on the type of hydrangea. Some types of hydrangeas bloom on new wood, mainly panicle (H. paniculata) and smooth (H. arborescens) hydrangeas.
Shane Hemphill, landscaping and design expert for Art of the Yard, says pruning new wood hydrangeas in the fall encourages new growth and plenty of buds in the spring. This is the best time to remove dead blooms and gently shape the shrub by trimming its branches.
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Hydrangeas (Old Wood)
Broadleaf (H. macrophylla) hydrangeas (including blue and pink flowering cultivars like ‘Nikko Blue’ and ‘Bloomstruck’) and oakleaf hydrangeas (H. quercifolia) form on old wood.
Usually the rule of thumb for these hydrangeas is to prune them after flowers start to fade in summer, and no later than August. The exception is removing damaged branches.
Gardening expert Laura Janney says pruning these hydrangea varieties in fall to remove dead or unhealthy branches can help preserve the shrub’s form and overall health.
Janney also warns that pruning old wood types of hydrangeas in fall risks losing next year’s blooms. Leaving these hydrangeas alone until spring allows them to put their energy into forming the next season’s flowers.
Always do your research, says Janney, to make sure you’re pruning at the right time, as not all perennial shrubs need to be cut back for the winter.
‘Knock Out’ Roses
Most rose growers know to stop pruning roses by late summer, to let them go gently into their winter dormancy. Pruning stimulates new growth, which can make roses vulnerable to winter damage.
One exception is the popular ‘Knock Out’ rose cultivars, which bloom on new growth. These prolific bloomers benefit from assertive pruning. To control their size, they can be cut back by up to a third of their mass once per year, which can be done in a post-blooming period of rest, such as in late autumn, without sacrificing next year’s blooms.
Spirea
Hemphill recommends pruning spirea in spring, to maintain their shape and remove any weak or dead branches. He says fall pruning encourages healthy, compact spring growth for these shrubs, which tend to get a bit more leggy as they mature.
Be sure to check underneath for dead branches near the base, and remove them to keep the shrub looking neat.
Ornamental Grasses
While not technically shrubs, large clumps of ornamental grasses serve similar functions to shrubs in the landscape, such as providing structure, sculptural form, shade, and wildlife habitat.
Hemphill recommends leaving these standing through winter, to provide shelter for birds and beneficial insects. They can also provide winter interest, especially if they have showy seedheads.
However, some ornamental grasses may reseed aggressively, including foxtail barley, bullrush, and prairie cord grass. To prevent the seed heads from reseeding, do a preliminary light prune by trimming off the tops in fall, then cut the clumps back fully in spring. Hemphill says doing the main pruning in spring prevents winter damage to tender young shoots and gives them a clean start for the new season.
Gardenia
Loved for its deliciously fragrant flowers, the gardenia is a tropical evergreen shrub with glossy leaves that is a favorite in Southern gardens.
The prolific blooms in summer start to fade as autumn arrives. This is the time to remove spent blooms and to gently shape the shrub by removing any damaged or leggy branches.
Beautyberry
These deciduous shrubs produce bright purple berries that attract songbirds in summer and autumn.
Though normally beautyberry (Callicarpa americana) is pruned in late winter before new spring growth emerges, some gardeners in northern zones prefer pruning it back hard in late autumn, because the old growth can be unsightly in the winter landscape.
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