How to Prune Hydrangeas

Pruning Bigleaf Hydrangea

Bigleaf hydrangeas bloom on old wood, setting their flower buds from late summer to early fall. If you mistakenly prune in the spring or even late fall, it will remove the flower buds and any chance of getting blooms for a year.

Bigleaf hydrangeas do pretty well without any pruning, but if necessary, to control their shape or size, prune them carefully just after the flowers have faded, never removing more than one-third of their total growth.

1. Deadhead Spent Flowers

   When most of the flowers have faded, it's time for pruning to keep the plant looking tidy. Use bypass pruners to clip away spent blooms.
   

2. Prune Away Dead and Weak Stems

   • Prune away stems that are dead or weak.
   • Don’t prune all the old wood because this is what will keep flowering as the new growth matures.

3. Prune for Size

   If your hydrangea has outgrown its space and you need to prune it, you can prune away select branches to curtail its size.

   • Prune away select branches all the way to ground level or to a main stem, but make sure to retain some healthy branches to avoid losing all the flowers.
   • A bigleaf hydrangea can be pruned back by one-third of its total mass, but harsher pruning will weaken the shrub and cause it to languish for a season or two.
     

   Warning

   Bigleaf hydrangea is the variety most susceptible to winter bud injury. If you live in an area with severe winters, give it winter protection by tying the branches together and wrapping them with burlap. Remove the burlap when the buds begin to swell.

Pruning Oakleaf Hydrangeas

Oakleaf hydrangea is an old wood bloomer easily recognized by its oak leaf-shaped foliage. Because its major attraction is the foliage, any loss of blooms is less disappointing than in most other hydrangea varieties.

Be somewhat cautious when pruning an oakleaf hydrangea. Prune to control size or shape, not to stimulate new growth.

1. Prune Out Winter Dieback

   • Inspect your shrub in the early spring before growth has begun.
   • If your shrub has experienced winter dieback, prune the stems below the point of injury.
   • Further pruning should wait until the plant has finished flowering.

2. Prune for Shape

   Don't feel obliged to prune it unless it is essential to maintain the plant's size or shape.

   • If it requires hard pruning, do it immediately after flowering.
   • This variety is not fond of heavy pruning, so never remove over one-third of the plant's total mass.
   • Use sharp bypass pruners to remove branches that interfere with the shrub's desired shape.
   • Cut selected stems to just above where they meet the main stems.

Pruning Mountain Hydrangeas

Mountain hydrangeas are small flowering old-wood blooming shrubs with narrow, pointed leaves and flattened flower heads. Because of their similar flowers, this plant is sometimes confused with bigleaf hydrangea. However, this type doesn't have the big leaves of H. macrophylla. 

Pruning should be done cautiously—or not at all—if it is not required to control the shrub's shape.

1. Remove Dead or Dying Stems in Early Spring

   In early spring, before new growth has started, dead or winter-damaged stems can be removed with pruners all the way to ground level.

2. Prune for Shape

   • This is not a shrub that always requires annual pruning.
   • If major pruning is necessary, wait until the shrub has finished flowering to trim back stems to a pair of healthy buds using bypass pruners.

Pruning Climbing Hydrangea

The stunning climbing hydrangea is the type you see slowly making its way up a tree or other support. It is a woody vine, blooming on old wood, that usually requires little to no pruning except to control its size.

1. Prune to Control Size

   Once climbing hydrangeas become established, they can grow quite vigorously and might need occasional hard pruning to set boundaries for the coming season.

   • Prune immediately after the plant flowers.
   • Most flowers occur at the top of these plants so that side trimming will have less impact on the plant's appearance.

2. Special Pruning to Rejuvenate a Neglected Plant

   • Neglected, overgrown vines can be cut back to ground level in early spring to rejuvenate the plant.
   • Hard pruning may reduce flowering fairly dramatically for one or two seasons.

Pruning Smooth Hydrangea

Smooth hydrangea, including the popular cultivars H. arborescens 'Grandiflora,' 'Annabelle', and 'Incrediball', don't usually have any problems blooming, though their white flowers aren't as showy.

It's a round shrub with leaves that are somewhat rounded with a pointed end, paler on the underside than on the top. Blooming on new wood, smooth hydrangea does well with fairly aggressive pruning in early spring.

1. Remove Dead or Injured Branches

   • Begin by removing any branches injured or killed over the winter.
   • These branches should be removed back to the main stem or ground level.

2. Trim for Shape

   Light pruning produces a large shrub with many small flower heads.

   • Additional branches can be lightly trimmed to shape the plant and retain its rounded shape.
   • "Light trimming" means removing as much as one-third of each stem's length.
     

3. Prune Hard for Large Flowers

   • Hard pruning of smooth hydrangea (12 to 18 inches from the ground) often creates a shrub with fewer but much larger flower heads.
   • Overly large flowers may require propping.
     

Pruning Panicle (Peegee) Hydrangea

Also known as peegee hydrangea, panicle hydrangeas produce football or cone-shaped flower clusters in mid to late summer. The flowers start white, cream, or green and slowly turn pink, drying and remaining on the plant long after the leaves have fallen. Panicle hydrangea blooms on new wood; it accepts—and even prefers—fairly heavy pruning.

1. Deadhead Spent Flowers

   • During the growing season, you can deadhead the flowers (remove spent flowers) as they fade.
   • Pruning helps prolong the bloom season as the plant puts more energy into continued blooming.

2. Prune Lightly to Maintain Shape

   • Once the flowers become unattractive, clean up the plant's overall shape by selectively pruning branches and the faded blooms.
   • Panicle hydrangea makes for an attractive shrub even after flowering is complete.
     

3. Do Hard Pruning in Late Winter or Early Spring

   • Hard pruning of individual stems in late winter or early spring keeps the plant from overgrowth and encourages healthy growth and flowers.
   • Panicle hydrangeas can be pruned by 1/3 of their total mass without damage to the plant.
   • Pruning out smaller wood to ground level leaves only the larger stems, which can also be partly trimmed back if needed to maintain size.