For years, lilacs and dogwoods have headlined the rather limited palette of plants that comprised the primary medium to taller shrubs which people could plant in their yards. Unfortunately, other than during the blooming season or in the fall as in the case of dogwoods, few of these shrubs could provide any dramatic foliage color in northern climates. Though purple leaf sandcherry (Prunus x cistena) offered purple foliage, it use was often curtailed because of questionable winter hardiness in many parts of the North, along with a susceptibility to chlorosis in alkaline soils. Also, many insect problems and rabbit attacks made the sandcherry too risky for many to consider.

	Dart's Gold

But in the last decade, hybridization has brought about a revolution in foliage color with an indigenous but little known North American plant - the common or eastern ninebark (Physocarpus opulifolius). For the most part these members of the Rose family are large, 5 to 10 foot tall and wide, densely foliated deciduous shrubs, with spirea-like whitish to pale pink flower clusters, which make them ideal as showy background plants in a large garden or even as a tall hedge. Extremely hardy, they thrive in hardiness zones 2 to 5 and are largely unaffected by light to medium shade, though full sun is the preferred growing location.

Ninebarks get their name from the characteristic vertically exfoliating bark on all species and cultivars, which has fostered a gardening legend that the plant has ‘nine layers’ of bark. The exfoliating bark itself is a very ornamental feature, particularly in winter. Though these large deciduous shrubs require some annual pruning immediately after blooming, the lack of any significant pest problems, along with an adaptability to most sun and soil conditions, has witnessed a redefinition of Ninebarks as a relatively carefree plant - ideal for any gardener.

Exfoliating bark

One of the earliest cultivars available on the market was the golden ninebark (P.o. ‘Luteus’) which as the name suggests was desirable because of its season-long yellow to chartreuse leaf coloration. However, during the ‘tight and compact’ years of the last two decades of the 20th Century, efforts to develop smaller and smaller shrubs became the primary focus of plant developers. As a result, Dart’s Gold ninebark (P.o. ‘Dart’s Gold’) and dwarf ninebark (P.o. ‘Nanus’ (syn. P. monogynus)) were introduced and became relatively common in northern gardens. Though holding great potential for short two-foot high hedges, dwarf ninebark has still never been utilized to it fullest extent in our northern climate.

Lacking any true exciting characteristic other than the golden foliage of Dart’s Gold, early ninebarks never really made much of an impact in everyday North American residential landscapes - at least, not until now. The new millennium saw the introduction of many new plants, of which ninebarks have been one of the greatest success stories by far.

	Diablo flowers

The ninebark revolution began with the introduction of Diablo ninebark (P.o. ‘Monlo’) in 1999. Diablo gets it’s rather descriptive name from the virtually black leaves. This dark beauty began showing up in gardens throughout North America almost immediately. But the millennium also revealed that the colorful foliage offered by Diablo greatly outweighed the need for a compact miniature shrub - this one is not that compact at all!

Growing easily to a height of 6 to 8 feet tall, its placement in the landscape needs to be greatly considered. However, the strong contrast between the mahogany-purple leaves and the pinkish white flowers creates an ethereal illusion that the flowers are somehow hovering in a void in the garden. This is exceptionally true when this dark ninebark is planted in a semi-shady or cooler-colored area. Another feature of Diablo is the graceful arching branch characteristic, reminiscent of bridalwreath spirea (Spiraea x vanhouttei), allowing for interesting cut flower branches for interior decorating purposes.

Summer Wine

Diablo ninebark has also been employed as a source for the hybridization of many of the newer cultivars of Physocarpus opulifolius that are recently making their way into our gardens. Summer Wine (P.o. ‘Seward’) is a sport of Diablo and P.monogynus, which results in a smaller coarser-leafed variety of Diablo, to appease the remnant minimalists in the gardening crowd.

Coppertina (P.o. ‘Mindia’) is a French introduction, which should come as no surprise since ninebarks have become quite popular in Europe as well. Growing potentially to 6 to 8 feet in height, its early golden-orange to red spring leaf color is truly unique in the northern landscape. As the plant ages, both the scarlet leaves and white flower clusters fade to reds, giving the plant its persistent coppery color. Developed as a hybrid of Dart’s Gold and Diablo, Coppertina has a somewhat more compact and upright habit, being a little taller than it is wide. The uniqueness of this plant has made it one of the most highly sought after new plant varieties for northern gardeners.

	Center Glow

Arising out of the same parentage is a recent Bailey Nurseries (St. Paul, MN) introduction, but with a different coloring habit. The foliage of Centre Glow™ ninebark (P.o.’Centre Glow’) begins strikingly similar to Dart’s Gold, but quickly transforms to burgundy from the outside edge of the leaves inward - leaving the characteristic center of the leaf appearing to glow a bright gold. As the plant continues to age through the growing the season, the older leaves are always considerable darker than the newer emerging leaves, leaving the plant with a constantly dynamic, ever-changing appeal. In autumn, the leaves take on an extremely bright scarlet color, which rivals anything in the current Northern landscape.

Two other ninebarks of note are Nugget (P.o. ‘Nugget’) and Snowfall (P.o. ‘Snowfall’) which like all other ninebarks are appropriately named. Nugget is an improved form of Dart’s Gold ninebark with smaller leaves, while Snowfall is a large green ninebark with more abundant flower clusters.

Coppertina

One final feature of ninebarks is that they are truly cold climate plants, rarely capable of surviving hotter humid weather anything further south of Zone 7. As landscape plants they can and should be pruned regularly, and even a harsh pruning every few years can keep an unruly ninebark under control. With the great color variation of purple, green and yellow, ninebarks offer a foliage color opportunity for any landscape, regardless of the size, sun or soil conditions.

And developers are seriously attempting to improve on the cultivars which we do have already. Improvements in color, color variegation, size, and habit are continuously being sought. If you can’t find a ninebark that fits your precise landscaping needs today, try again in a few years - you just might find it at a garden center near you.

So until next time... Happy Gardening in the exciting world of ninebarks!

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