Pruning Hydrangeas

 

Hydrangea anomala petiolaris – the climbing Hydrangea is a vigorous, woody vine that is often grown on a fence, arbor, large tree, or side of a house. It requires no regular pruning, other than to fit the space available.

  • After flowering in summer, any wayward vines may be shortened by trimming back to just above a bud, or removed completely.
  • To thin a congested plant, a few stems may be removed by trimming them back to the point where they attach to the plant.
  • Spent flower clusters may be removed after blooming, or in early spring.
  • Trimming should only be done on a small scale annually.
  • Dead wood should be removed any time, as noticed.

 

Hydrangea arborescens – the smooth Hydrangea bears large, round balls of white or pink flowers. The best known varieties are ‘Annabelle’, and ‘Incrediball’. They flower on the current year’s growth and require minimal pruning.

  • In late winter or early spring, while dormant, remove any damaged or crossing branches, and any spent flowers that may remain.
  • Although these plants are sometimes cut entirely to the ground in the fall or spring, resulting in heavy flowering and large blooms the following summer, the resulting stems will often flop over due to the weight of the large flowers. To avoid this, leave a woody framework of at least two feet.
  • Dead wood should be removed any time, as noticed.

 

Hydrangea macrophylla, H. serrata – the bigleaf hydrangea produces pink to blue flowers. It typically flowers mid to late summer on the previous year’s growth, or old wood. However, some new varieties, such as ‘Endless Summer’, also flower on growth from the current season, or new wood. These usually require very little pruning.

  • Pruning can be undertaken in early to mid-spring, when the buds begin to swell & turn green. Simply trim off any spent flowerheads to the first pair of buds underneath each flowerhead (deadheading may also be done in summer, after flowers begin to fade).
  • Dead stems with no green buds should be removed completely.
  • On established shrubs, a quarter to a third of the oldest stems can be cut to the base, which will result in new, vigorous growth, and even more flowers.
  • Avoid cutting the entire shrub back hard, or blooming will be delayed by a year or more.

 

Hydrangea paniculata – the late panicle Hydrangea (e.g. ‘Limelight’, ‘Pinky Winky’) has large, conical clusters of white or pink flowers in late summer through autumn. It blooms on the current year’s growth.

  • In late winter or early spring, prune out any damaged or crossing branches, and trim back any wayward shoots that spoil the shape.
  • For larger flower clusters, prune back last year’s branches to a low, permanent, woody framework in the spring, when buds start to swell.
  • Remove dead wood any time, as noticed.

 

Hydrangea quercifolia – the oakleaf Hydrangea bears white, conical flower clusters in summer on old wood, and requires very little pruning.

  • In late winter or early spring, prune out any damaged or crossing branches; the remaining branches should be well-spaced and form a permanent framework.
  • Spent flowers should be removed at this time, or after fading in autumn, but avoid cutting into live, green tissue, or you may be trimming off new flower buds.
  • Dead wood should be removed any time, as noticed.