How to Prune Flowering Shrubs: Spring vs Summer Bloomers

Spring bloomers and summer bloomers

Spring bloomers: right after flowering. Penn State says shrubs that bloom before mid-June should be pruned after flowering: their flower buds develop the season before, on “old wood”, so an early cut removes them. Missouri says to prune them as soon as possible after blooming, when wounds heal quickly and dead wood is easy to see. Iowa State says light to moderate pruning right after flowering lets you enjoy the display and leaves time to set next year’s buds.

Summer bloomers: late winter or early spring. University of Illinois Extension says shrubs that bloom after July 1 flower on the current year’s growth and are best pruned in late winter or early spring. Missouri prunes them any time before new growth begins in spring, and Penn State says it is because their buds form on new wood in the same season.

⚠️ Two places the lists split a genus. Viburnums are spring bloomers to Penn State and Missouri, but Clemson lists American cranberrybush viburnum with the shrubs pruned before spring growth. And hydrangeas and roses go both ways by type: see hydrangeas by type and roses. Camellias and gardenias are the third: Clemson’s list puts them before spring growth, while NC State prunes camellias right after flowering and Clemson’s own gardenia page and UF/IFAS prune gardenias after they flower. See camellia and gardenia.

Renewal: a third of the oldest stems

Penn State’s method for a flowering shrub is renewal pruning: cut some of the largest stems to the ground, and new ones grow from the base. It keeps the shrub’s natural shape, lets light and air into the middle, and increases flowering, because older stems flower less. Take no more than one-third of the largest stems, and there is no need to paint the cuts; they seal on their own.

1. First the small stuff. Missouri removes weak growth and dead, diseased, split or crossed branches with hand shears, working from the top of the shrub down.
2. Then the oldest canes. With loppers or a pruning saw, Missouri cuts as many of the oldest canes at ground level as it can without changing the shrub’s form — a quarter to a third of the stems each year, so the whole shrub is renewed every three to four years. Minnesota takes up to a third of the oldest, thickest stems each year.
3. Then shape, lightly. Penn State shortens a third of the younger stems with selective heading cuts, back to a bud, to control size. Clemson heads stems back to several different heights, on a slight slant 1/4 inch above a bud facing the way you want the growth to go, and prefers thinning cuts, back to a side branch, which fill out the inside.

Rejuvenation: starting an old shrub over

For an overgrown shrub that no longer flowers, Penn State cuts all the stems back to the ground in early spring. It may delay flowering for several years, but gives a more manageable shrub; forsythia, lilac and spirea respond well. Minnesota does the same for multi-stemmed, cane-growth shrubs in early spring, as close to the ground as possible, and says that season’s flowers may be lost. Iowa State does it in late winter or early spring, March or early April, and says it can cost a spring-flowering shrub its flowers for 2 or 3 years.

Clemson calls it renewal pruning and cuts the plants to within 6 to 12 inches of the ground before spring growth begins, then tips the new shoots once they are 6 to 12 inches long so they branch. It says most broadleaf shrubs — azaleas, camellias, privets, glossy abelia, nandina and cleyera — respond well, while boxwoods, junipers, arborvitae, yews and other narrow-leaf evergreens may decline. Its gentler alternative takes three years: a third of the old stems the first year, half of what remains the next, and the rest the third.

Some shrubs are cut down every year. Missouri says butterfly bush and beautyberry are often cut to the ground in spring, and Minnesota cuts smooth hydrangeas and late-blooming spireas to the first pair of buds above the ground. Missouri warns the opposite for pyracantha and Japanese quince, which flower and fruit on wood more than a year old: never prune them hard at one time.

Shrubs grown for their leaves or bark

Iowa State says deciduous shrubs without showy flowers, grown for colored bark, fruit or foliage, such as burning bush, are pruned in late winter or early spring before growth begins. Minnesota says the same of shrubs grown mainly for their foliage. With no flowers to lose, the only rule is to finish before the new leaves.

Not in late summer or fall

Iowa State says not to prune deciduous shrubs in August or early September, which may push a late flush of growth that does not harden before cold weather. Penn State and Missouri say the same about late summer and fall. For a spring bloomer it is doubly costly: the buds for next spring are already on the shrub. Full guide: What Not to Prune in Fall, and the Cuts That Are Fine.

Common mistakes

• Pruning a spring bloomer before it flowers. Its buds formed last year (Penn State, Missouri).
• Shearing the whole shrub to one height. It destroys the natural shape (Penn State).
• Taking more than a third at once. Penn State’s limit for renewal pruning.
• Hard-pruning a narrow-leaf evergreen. Clemson says junipers, boxwoods and arborvitae may decline.
• Pruning in late summer. The new growth does not harden before winter (Iowa State).
• Painting the cuts. Penn State says there is no need; the wounds seal on their own.

Every pruning guide

• When to Prune by Zone: Late Winter or After Flowering
• When and How to Prune Roses by Zone
• Pruning Fruit Trees in Late Winter: Apple, Pear, Peach
• How to Prune Flowering Shrubs: Spring vs Summer Bloomers — this page
• What Not to Prune in Fall, and the Cuts That Are Fine
• How to Prune Evergreen Shrubs and Hedges
• How to Prune Hydrangeas by Type: Old Wood vs New Wood
• Hydrangea Pruning Chart: When to Prune Each Type
• How to Prune Limelight Hydrangea and Vanilla Strawberry
• How to Prune Annabelle and Incrediball Hydrangeas
• How to Prune Endless Summer Hydrangeas (Rebloomers)
• How to Prune Oakleaf Hydrangea: After It Flowers
• Hydrangea Tree Care and Pruning (Tree-Form Panicle)
• How to Prune Crape Myrtles Without Crape Murder
• Your USDA hardiness zone by ZIP code

Where there is no source here

We found no Texas or Georgia source on pruning flowering shrubs we could read; University of Georgia Extension’s pages would not load from here. The South is covered by Clemson for South Carolina and UF/IFAS for Florida, which says to prune flowering hedges after they bloom so the buds are not cut off.