Bigleaf, oakleaf, mountain and climbing hydrangeas flower on old wood: prune them right after the flowers fade, and by August 1 at the latest, because they start forming next year’s buds in August and September (Illinois Extension). Panicle and smooth hydrangeas (Limelight, Annabelle) flower on new wood: prune them in late winter or early spring, before new growth starts. Reblooming bigleaf types (Endless Summer) go in early spring or after their first flush of flowers.
Old wood or new wood: the one thing to know
Old wood is any stem at least a year old. Hydrangeas that bloom on old wood form their flower buds in late summer and fall, and the buds wait on the bare stems all winter before opening the next summer (University of Maryland). Cut those stems in fall, winter or spring and the flowers go with them. Many hydrangeas can’t replace buds that were cut off.
New wood is this year’s growth. Hydrangeas that bloom on new wood form their buds just before they open, so in winter their stems carry no flower buds at all. Cutting them back before growth starts costs you nothing.
Reblooming (remontant) bigleaf varieties do both: the old-wood buds open first, then new-wood flowers keep coming into summer (University of Maryland). If winter kills their buds, they still flower on new growth (Illinois Extension).
Which hydrangea do you have?
| Type | How to recognize it | Blooms on | Prune |
|---|---|---|---|
| Bigleaf (H. macrophylla) | Big round “mophead” or flat “lacecap” flowers, blue, purple or pink depending on the soil | Old wood | Just after flowering |
| Mountain (H. serrata) | Like a smaller bigleaf, with lacecap flowers that can be blue | Old wood | Just after flowering |
| Oakleaf (H. quercifolia) | Leaves shaped like oak leaves; cone-shaped cream flowers in June that age to pink | Old wood | Soon after flowering |
| Climbing (H. anomala petiolaris) | A vine that clings to walls and trees, up to 40 ft; flat white flower clusters | Old wood | After flowering, if at all |
| Panicle (H. paniculata) | Cone-shaped white or green flowers that turn pink; the last to bloom. Limelight, Quick Fire, “PeeGee” | New wood | Late winter or early spring |
| Smooth (H. arborescens) | Big round white or pink “snowball” flowers. Annabelle | New wood | Late winter or early spring |
| Reblooming bigleaf | A bigleaf sold as reblooming: Endless Summer, Let’s Dance, Tuff Stuff | Old and new wood | Early spring or after the first flowers |
Descriptions from the University of Maryland and Illinois Extension. Only bigleaf and mountain hydrangeas can have blue or purple flowers (University of Maryland), so a blue hydrangea is an old-wood type.
The pruning calendar
The extension services give seasons rather than dates, because flowering and spring growth move with your climate. In Georgia, bigleaf and oakleaf hydrangeas are pruned in late spring or early summer, right after they bloom (UGA Extension).
Just after the flowers fade, and by August 1 at the latest · UMD, Clemson, Illinois Extension
Soon after it blooms in June · Clemson, Illinois Extension
After the flowers fade; rarely needs it · UMD, Illinois Extension
Late winter or early spring, before new growth starts · UMD, Clemson, Illinois, UGA
Late winter or early spring, before new growth starts · UMD, Clemson, Illinois, UGA
Early spring, or just after the first flush of flowers · UMD; Clemson for Endless Summer
Should you cut hydrangeas back in fall?
Not the old-wood types. By fall a bigleaf or oakleaf hydrangea already carries next summer’s buds, so cutting it back in fall or winter removes them. Illinois Extension gives three reasons a hydrangea doesn’t bloom: not enough sun, an early frost, or pruning at the wrong time.
Panicle and smooth hydrangeas can be cut back in fall, and often are. Illinois Extension warns that cutting them back hard every year weakens the plant, and suggests doing it every other year or every third year. The University of Maryland would still avoid pruning any hydrangea close to winter dormancy.
You can leave the dried flowers on all winter. They do no harm, and their faded colors give the garden some winter interest (University of Maryland). Cutting off spent flowers (deadheading) is fine any time after they fade, on any type, as long as you cut only the flower and not further down the stem (University of Maryland).
How much to cut
- Bigleaf and mountain: after flowering, the University of Maryland trims them to about 12 inches off the ground; Clemson removes no more than a third of the plant’s growth.
- Oakleaf: prune to the same height or leave it taller, especially large varieties (University of Maryland). Often it needs nothing but shaping (Illinois Extension).
- Smooth: in late winter, trim to about 12 inches (University of Maryland). Cut back and thinned, it makes fewer but bigger flower clusters.
- Panicle: the same height or taller. Illinois Extension allows removing a third to half of the shrub. On a tree-form panicle, don’t cut the trunk down unless you want it to grow back as a shrub (University of Maryland).
- Reblooming bigleaf: remove as little as possible, since pruning early delays the first flowers and pruning mid-season can cut the rebloom short (University of Maryland).
On any type, take out dead, damaged and crossing stems, and thin crowded bigleaf and mountain hydrangeas at the base to let air through, which helps against leaf spot (University of Maryland). Make each cut just above a healthy bud with sharp, clean pruners (UGA).
Cold winters, late frosts and lost flowers
A bigleaf hydrangea can lose its buds without any pruning. Freezes can kill only the flower buds or whole stems, especially when mild weather is followed by a sudden cold snap, or when a spring frost hits after growth has begun (University of Maryland). Reblooming varieties help gardeners whose shrubs keep losing buds to cold, deer or badly timed pruning: they flower on new growth even after the old buds are lost (University of Maryland).
So in spring, wait until the shrub leafs out. Then you can see which stem tips died over winter and cut back to live buds (University of Maryland). Check your hardiness zone before buying a bigleaf, and your last frost date to know when late frosts stop.
Questions people ask
When do you prune Endless Summer hydrangeas?
Right after the first flush of flowers, or in early spring (Clemson, University of Maryland). They then flower again on new growth through the summer.
When do you prune Annabelle hydrangeas?
In late winter or early spring, before new growth emerges. Annabelle is a smooth hydrangea and blooms on new wood (Illinois Extension, Clemson).
When do you prune Limelight hydrangeas?
Late winter or early spring. Limelight is a panicle hydrangea and blooms on new wood (Illinois Extension).
What happens if you prune hydrangeas at the wrong time?
On bigleaf, oakleaf, mountain and climbing hydrangeas you cut off the flower buds, and you get few or no flowers that year. You lose that year’s flowers, not the shrub: if flowers don’t matter to you, the University of Maryland says timing matters much less. Panicle and smooth hydrangeas bloom anyway.
Should you deadhead hydrangeas?
You can, but you don’t need to. Cut off only the faded flower, any time after it fades. It may help reblooming varieties flower again sooner (University of Maryland).
Can you prune hydrangeas in spring?
Panicle and smooth types, yes, before growth starts. On bigleaf and oakleaf, only remove dead stem tips in spring; the live buds are this summer’s flowers.
Sources
- University of Maryland Extension, Pruning Hydrangeas (Miri Talabac, 2024): old wood, new wood and remontant groups; prune old-wood types just after flowering and new-wood types in late winter or early spring; heights; reblooming types; thinning, heading back, renewal and deadheading; winter and spring frost damage; only bigleaf and mountain hydrangeas are blue or purple; avoid pruning close to dormancy.
- University of Illinois Extension, For showy blooms, pruning hydrangeas is all about the timing (Ken Johnson, 2020): old-wood types form buds in August and September, prune by August 1 at the latest; reblooming bigleaf varieties; new-wood types in late winter or early spring, often cut back in fall, every other or third year.
- University of Illinois Extension, How to properly prune hydrangeas (2022): a third to half of new-wood types; identification of panicle, smooth, bigleaf, oakleaf, mountain and climbing; why hydrangeas don’t bloom.
- Clemson Cooperative Extension, Home & Garden Information Center, Pruning Hydrangeas (2020): bigleaf just after flowering, no more than a third; Endless Summer after the first flush; panicle and smooth in late winter or early spring; oakleaf blooms in June, prune soon after.
- UGA Extension, Fulton County, The Comprehensive Guide to Pruning Hydrangeas (John Fox, Master Gardener; 2025): bigleaf and oakleaf in late spring or early summer after flowering in Georgia; panicle and smooth in late winter or early spring; cuts above a healthy bud with clean tools.