How Much Should You Cut Back Hydrangeas in Fall?

Fall is perfect for planting hydrangeas, but it’s often not the best for cutting them back. Fortunately, these easy performers usually don’t require regular pruning. If you need to prune to rejuvenate growth, promote a shapely form, or reduce size, it helps to know what type of hydrangea you have to determine the right time. Cutback stimulates new growth, which is challenging as the shrubs prepare to overwinter and can risk future flowering, depending on the selection. 

Fall isn’t off-limits with more flexible species, but late winter and early spring are generally the best times to prune even these, while summer is optimal for others. Fall is ideal for transplanting hydrangeas, a great solution if you’re constantly pruning to manage size.

Hydrangeas are durable, woody shrubs that thrive across a wide range of climates and growing conditions. With the right hydrangea in the right spot, you’ll enjoy carefree growers loaded with blooms. Knowing your type of hydrangea and a few pruning notes will lead to a long-lasting floral show, as anticipated.

Old Wood vs. New Wood

Hydrangeas bloom either on old wood (the previous year’s growth) or new wood (the current year’s growth). This old/new bloom sequence is helpful when it comes to pruning and cold hardiness.

Species that bloom on old wood set their buds in late summer – just after flowering – for blooming the following year. An old wood hydrangea pruned in the fall means cutting off buds and a lack of flowering come summer. Old wood buds are also susceptible to winter damage, where they may freeze and drop in extremes, meaning there won’t be a showy bloom display next year.

Hydrangeas that bloom on new wood set their buds in the spring on fresh stems. This late set means buds don’t endure cold winter temperatures. They emerge closer to seasonal bloom time. A new wood hydrangea takes pruning in fall or late winter and still blooms that summer.

Pruning Timing

There are six commonly grown species of hydrangeas, each with unique characteristics, from long bloom times to growth habits to fall color and winter interest. Hydrangeas don’t often need to be cut back, but it can be beneficial if you need to rejuvenate the shrub in the fall to improve its form or reduce its size for fresh growth.

It’s a best practice to prune out dead or weak stems anytime during the growing season, paying special attention in late winter and early spring for winter-damaged branches. This increases air circulation and makes way for new growth while reducing fungal disease problems.

However, always avoid cutting back old wood blooming hydrangeas in the fall. If you’re unsure whether you have an old or new wood species, avoid pruning and cutting back this time of year altogether. Be on the safe side of allowing buds to form without accidentally clipping them away. 

At any pruning time, check the stems before you make cuts. Buds are easy to see, and if you spot them, avoid removal.

To prune the more flexible new wood species in the fall, wait until they drop their leaves and enter dormancy. This helps stave off new growth, which becomes sensitive to damage. Winter dieback is a natural occurrence for mature stems, depending on seasonal conditions, and is another reason to wait until early spring to cut. Pruning, followed by winter dieback, may result in shorter plants.

Deadheading

Cutting off spent blooms with repeat-flowering varieties during the growing season helps promote faster reblooming. Leading into fall, consider leaving aging clusters in place for added winter interest. Many varieties transition to vintage tones and finally a buff tan, with a dry, papery texture that persists into winter until naturally dropping. 

When this isn’t appealing, depending on the look and preference, deadhead post-bloom and in early fall by clipping the flowerhead to a healthy set of leaves.

Old Wood Bloomers

The following species bloom on old wood with big exceptions: mountain hydrangeas and some bigleaf cultivars bloom on old and new wood for an extended season of repeat flowering. Treat these as old wood selections to preserve the greatest number of buds.

Cut old wood selections back in summer, as close to flowering time as possible, using deadheading as a good time to prune. These typically don’t need regular pruning.

Bigleaf

H. macrophylla features the large mophead and lacecap blooms that characterize the genus. The rounded flower clusters in blue, pink, white, and purple transition to pink and green as they age for attractive flowers into autumn.

Depending on the variety, traditional bigleafs bloom for about six to eight weeks from late spring to mid-summer in warm climates and from mid-summer to early fall in cooler temperatures. Cultivars like ‘Endless Summer®’ and ‘Let’s Dance®’ boast improved flowering and cold hardiness by setting buds on old and new wood. These bloom early and repeat bloom throughout summer until frost. 

Bigleaf hydrangeas generally don’t need to be cut back in the fall or any other time of year. If you choose to prune for shaping, do so right after plants finish flowering, cutting no more than one-third of the plant. Avoid pruning in the fall to retain old wood buds.

Oakleaf

H. quercifolia is a southeastern U.S. native. The upright shrubs bear creamy white pyramidal blooms. Their deeply lobed leaves show a brilliant red fall color. 

Blooms emerge mid to late spring through early summer and transition to pink and green by August and September. These are rugged, low-maintenance selections. Prune if necessary for size or shape in June or July post-bloom.

Mountain

H. serrata is similar in appearance to bigleaf but with a more compact form and smaller lacecap flowers. It blooms on old and new wood for a long-lasting display from early summer into fall.

Mountain hydrangea and its cultivars range in pink, blue, violet, and white hues. Remove flowering stems as they finish blooming and manage size by a one-third cutback in September.

Climbing

H. anomala subsp. petiolaris is a different form with woody climbing vines that reach 30 to 40 feet high in optimal conditions. Large, flat-bloom clusters of fragrant white flowers emerge in late spring through mid-summer. 

Climbing hydrangeas will produce new growth for setting buds with a summer trimming (if needed) to remove wild offshoots or reduce size.

New Wood Bloomers

Panicle and smooth hydrangeas bloom on new wood with more flexibility in the timing of their cutback. The exceptionally hardy and adaptable performers are durable selections across climate zones and growing conditions.

Some are vigorous, tall shrubs that may be annually reduced by one-third depending on the gardener’s preference. Others are dwarf to mid-range growers that won’t need size reduction for a full, dense habit. 

Panicle

H. paniculata features showy pyramidal blooms in colors from creamy white to lime green to pink tinged with red. Flowers appear in summer through early fall, transitioning to pink by September and October. Blooms fade to light buff in the winter for lasting texture and seasonal interest.

Panicle hydrangeas are among the toughest and easiest to grow. They bloom on new wood and are cold-hardy. Prune the robust shrubs for shaping or size in fall or late winter/early spring before new growth begins. Since they bloom on new spring growth, pruning old stems won’t impact budding and flowering.

Smooth

H. arborescens, also called wild or smooth hydrangea, is native to the United States and grows across varying climates. Buds emerge on new wood for white, ivory, and pink flowers, maturing to light green in late summer and tawny in fall.

Flowers appear in flat domes or round clusters from early summer through fall. Like panicles, the vigorous producers are flexible in their cutback. Early spring, before new growth emerges, is still the best for promoting new stems and buds.

Pruning Tips

When it’s the right time to trim, it always helps to protect plant health by using clean, sharp tools. For thick branches, loppers are handy, while bypass pruners work well for small cuts like deadheading and removing upper growth.

To begin, remove old canes first to improve air circulation and stimulate new production. For huge specimens like ‘Peegee’ panicle hydrangeas, some gardeners select three to five central canes to leave in place to support new stems, removing the others.