Nine Bark and Pruning Caryopteris ‘Dark Night”

(Question)

 

1. Nine bark did not bloom this year.  What might she have done wrong?

2. Should caryopteris ‘Dark Night’ be pruned and if so a) how much, and b) is this the time to prune?

(Answer)

Dear Gardener,

Ninebark, also known as Physocarpus sp. is a medium-sized shrub grown primarily for its interesting and colorful foliage. Ninebark is a shrub that flowers early in the season on one-year old wood, growing at or near ground level. Routine pruning for most ninebarks and cultivars is recommended just after flowering and no later than early August if flowers are desired next year. Prune out all wood older than one year old right to the ground or to a vigorous branch originating low on the plant.To overcome the leggy” growth habit, prune back the canesabout 1/3 just after flowering and branching will occur behind the cuts. As new growth sprouts with new branches, continue pinching back these new sprouts about 1 to 2 inches from the tips. This continuous pinching or pruning back will allow the shrub to become full-bodied and more compact. Flowers will be assured for next year if this pruning technique is then discontinued by early August.

The following website provides additional information: www.garden.org/plantguide/?q=show&id=3402

Caryopteris is a fall flowering shrub with rich blue to purple-blue flowers. While it is hardy to USDA zone 5, it is typically a die-back shrub in Ontario, behaving much like a Buddleia (butterfly bush).  The plant’s  woody stems are tender and die back during the winter. The plant grows back quickly in the spring and its flower buds (and flowers) are formed on new wood. Caryopteris loves full sun. It will grow in partial shade but it will not look happy or flower nearly half as well as a plant in full sun.  Caryopteris needs well drained soil. It will not tolerate heavy, wet clay soils. Once established Caryopteris is very drought tolerant.

Spring pruning can be approached in one of three ways:

  1. Prune all of the stems down to 6 to 8 inches in early to mid-April.
  2. Wait until May when buds begin to swell and growth emerges. Any wood that remains inactive can be pruned off at this time. Scratching the bark with your thumbnail will also reveal where green living wood merges into brown tissues where dieback has occurred.
  3. An intermediate approach is to prune the plant back in April by about one-third to help the shape and overall neatness. Wait until growth emerges later in May, then prune off any winter dieback that remains.

The following website provides additional information on this lovely subshrub: www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=b890

 

Good Luck with these beautiful shrubs.