Ninebark

Posted by shane - January 8, 2015 - A-Z Plant Maintenance, Shrubs - No Comments

Physocarpus opulifolius

Sheared 'Diabolo' ninebark in Calgary.  S. LePage photo.

Sheared ‘Diabolo’ ninebark in Calgary. S. LePage photo.

This is probably among the top five commonly planted shrubs in Alberta.  A healthy ninebark makes a nice accent in a shrub bed, and different cultivars offer a variety of foliage colours, from amber to purple to greenish-gold.  One of the nicest formal hedges I have seen was a hand-sheared golden ninebark hedge.  I don’t use ninebark in landscape design for two reasons: 1) it is in every other yard, and 2) it has a tendency to die-back severely over a harsh winter, leaving it one-sided, or just plain ugly.  I prefer shrubs that have a better chance of getting through winter intact.

If you choose to plant this shrub, give it the best chance of doing well by planting it in a good, well-drained soil with plenty of organic matter and a nice wood chip mulch.  Keep it moist and well-irrigated during the first season of planting.

Exposure

Full sun

Pruning time

Late winter for an open-centred shrub.  Mid-summer onward for a sheared specimen, and again in late summer for a touch-up trim.

Pruning and Shaping

There are three ways of dealing with a ninebark shrub.  The first is to let it grow naturally and do nothing to it, except cut back the odd wayward branch to balance the shape.  When the shrub gets severely overgrown, you can cut it back to within a few inches of the ground and grow a new shrub from the existing root system, and start the process over.

The second method of pruning is to create an open-centred shrub, and prune it in the same manner as a lilac, forsythia, or tatarian honeysuckle.  Each year, remove 1/3 of the stems from the base of the plant.  Remove major crossing, rubbing, and dead branches, and basically give the shrub a clean vase-shape appearance.  Some people like to shorten the remaining stems by about 1/3, but with ninebark, it just stimulates another growth flush on the top and the new growth twig colour looks awkward compared to the older stems.

My preference is the third method, which is to annually shear the ninebark into an upright oval shape, after the growth flush in late June or early July, and again later in the summer to “tighten up” the shape.  Most shrubs aren’t suited to shearing but ninebark tolerates it very well.

(c) 2015 Shane LePage, Wild Rose Garden & Tree Service Inc., Red Deer, AB.