Common ninebark (Physocarpus opulifolius) is one of those shrubs that I learned about in college and then forgot about until sometime around the Millennium, when purple-leaved Diabolo® transformed a humble native shrub into a fashionable garden plant. While not the first color form, Diabolo® grabbed attention and clearly spurred breeders to get to work. What followed was a raft of colorful selections, from duskier purples to eye-catching yellows. Indeed, enhanced color is the modern ninebarks’ cachet—burgundy, purple, yellow, red, orange, and coppery leaves in spring, summer, and fall. As green shrubs go, ninebark is serviceable albeit ho-hum; colorized, and it becomes something special.
Ninebarks Basic Facts
Physocarpus opulifolius and cvs.
Conditions: Full sun to partial shade; moist, well-drained soil
Native range: Eastern North America
Diseases: Fire blight, leaf spot, powdery mildew
Propagation: Softwood cuttings or root suckers for transplanting
This shrub has its detractors; after all, ninebarks can be large, coarse, and gangly. In his tome on woody plants, Michael Dirr archly dismisses ninebark: “The Minnesota Landscape Arboretum has a large collection of ninebarks and after looking over the entire group, I still came away with the opinion that about anything is better than a Physocarpus.” To be fair, that is his opinion from the 1990s, and he was referring to the world before Diabolo®.
It seems to me that ninebarks may still be a bit underappreciated, but I hope that’s not true for much longer. Perhaps the market saturation of the original colorized options—Diabolo®, Coppertina®, and ‘Center Glow’—made them ubiquitous, but their disease problems made them vexing. Newer introductions offer enhanced leaf colors, smaller habits, and disease resistance. Until recently, I had evaluated only three ninebarks in my career; that’s why I was eager to grow and compare the newest ones against the old standards. The trial is ongoing, but initial results are promising. So now is a good time to give ninebarks another look, or maybe a first look.
Ninebark Trial Parameters
The Chicago Botanic Garden is currently evaluating 26 different ninebarks in comparative trials that started in 2019.
How long: Three years into a six-year study
Conditions: Full sun; well-drained, alkaline, clay-loam soil
Care: We provided minimal care, allowing the plants to thrive or fail under natural conditions. Besides observing their ornamental traits, we monitored the plants to see how well they grew and adapted to environmental and soil conditions, while keeping a close eye on any disease or pest problems and assessing plant injury or losses over winter.
The vibrant foliage of Amber Jubilee™ is most radiant in spring, when it glows deep orange rather than the orange-bronze of similar cultivars such as ‘Center Glow’ or Coppertina™. The color shifts in midsummer to green with bronze-flushed, golden-yellow terminal leaves, and finally to an autumnal blend of orange, red, bronze, and purplish green. The white flowers are pleasing, and butterflies love them, but the kaleidoscopic color show is longer lasting and more satisfying. Amber Jubilee™ is a broad, vase-shaped plant with arching branches. Its light tawny twigs pair nicely with the light tan-gray exfoliating bark, which looks almost white when the branches are bare.
Red Robe™ is an evolution of exquisite colors from spring to fall. Leaves emerge glossy orange-bronze but quickly lose luster as they darken to bronze-brown with orangey overtones. The summer mantle of dark burgundy—flecked with golden-orange at the tips—glows red when backlit by the sun and becomes ruddier as summer winds down. I have not seen Red Robe™ at its full size—6 to 8 feet tall and wide—but am kind of giddy thinking about a big vase-shaped plant clad in all those rich colors. White flowers, flushed with purple, give way to bright red fruit clusters that ripen to deep burgundy in fall. Dark red-purple twigs fade to burnished copper in winter, contrasting beautifully with the hoary gray peeling bark.
‘Dart’s Gold’ has impressed me greatly, and more so for being more of an old-timer; there is never a minute that its colorful foliage disappoints. The brilliant golden yellow of its new leaves rivals that of spring-blooming forsythias! Early summer is a study in orange and gold—there is a nuanced gradation from top to bottom of bright orange, golden-orange, golden-yellow, and yellow-green. Although the foliage fades to mostly green in late summer, it turns brighter yellow again in fall with hints of coppery orange that glow like small flames at the tips. There are clusters of white flowers in late spring, but honestly, the dazzling leaves hog all the attention. The compact, rounded habit—4 to 5 feet tall and wide—is not as well-branched as that of some dwarf varieties, but it has more internal branching than many larger cultivars. Dark tawny twigs and light tannish bark stand out in a snowy winter garden.
Tiny Wine® is one of the original compact cultivars with small leaves and many slender side branches. The leaves, held on coppery twigs, open bronze-green and then age to dark burgundy-green before settling in late summer on deep green with a burgundy overlay. In fall, red smolders from the center outward; the final mix of burgundy and red is quite good. Pink-flowered Tiny Wine® shares a similarity to Sweet Cherry Tea™, but its leaf coloring is darker. In the winter landscape, its well-branched habit shows best, with cinnamon twigs sprouting from exfoliating tan-gray bark. This variety stays trim and neat.
Festivus Gold® is as luminous as ‘Dart’s Gold’ but is even more radiant, if that is possible. The golden yellow spring foliage matures to yellow-green, with terminal leaves remaining bright yellow all summer. In fall the leaves are flushed with orange and bronze but never really lose their golden glow. The tidy, rounded habit with ascending light copper-colored branches is more compact than ‘Dart’s Gold’—3 to 4 feet tall and wide—making Festivus Gold® perfect for small landscapes. The tan exfoliating bark reveals soft salmon tones, which reminds me a bit of river birch. The best part, Seinfeld fans, is that airing grievances and engaging in feats of strength are not required to enjoy this plant.
Tiny Wine® Gold
Tiny Wine® Gold is the yellow version of Tiny Wine® and features a similarly tight, refined habit and size, small leaves, and increased branching. White flowers, opening from pink buds, liberally pepper the branches in late spring. Labeling it simply yellow is lazy—it is in truth a bonanza of color from spring through fall. Leaves open golden green on reddish purple twigs, gradually becoming a mix of yellow and green, with each stem crowned in orange-copper in summertime. Interestingly, fall color develops in reverse—soft orange and yellow with burgundy tinges flush upward from the bottom, leaving the tips green until last. Come winter, twigs fade to tawny above light tannish gray bark; this shows more prominently in the landscape because of the branching pattern.
The slightly arching stems of Ginger Wine® are clothed in rich burgundy foliage in summer and fall but start out very differently. The red-orange-bronze leaves are strikingly beautiful against the whitish bark as they unfold. (Game of Thrones nerd alert—the colors at this point remind me of the red and white weirwood trees of Westeros.) The dark burgundy summer twigs mirror the leaf color perfectly; winter twigs are a lighter cinnamon. Much like Red Robe™, the deep burgundy fall color is accented by redder leaves at the tips. The bushy vase-shaped habit looks more open in spring and winter because side branching is less pronounced than on Tiny Wine®.
Learn ninebark pruning basics
It’s a good idea to cut out dead, crossed, or leggy stems on a ninebark every year in late winter or early spring. Aside from that general maintenance, there are three solid pruning methods you can employ. But keep one important fact in mind before you start: Ninebarks flower on old wood, so any early season pruning decreases the bloom, while pruning after flowering decreases fruit.
Selectively remove up to a third of the oldest stems each year (in late winter) over a three-year cycle. This is a stepped approach to rejuvenation and improves air circulation, which can help alleviate powdery mildew infections.
Give the shrub a light, postbloom shearing to head back any errant or overly vigorous stems and even out the summer habit.
Renewal or rejuvenation pruning is a good technique for overgrown or scraggly ninebarks. Cutting all stems to the ground in late winter allows you to start over. Plants will be compact for a few years but will eventually reach their full size. Flowers and fruits for the year are sacrificed every time this is done, so do it sparingly. The exfoliating bark on older wood is also less pronounced for several years until stems gain some age.
Richard Hawke is plant evaluation manager at the Chicago Botanic Garden in Glencoe, Illinois.
- Nature Hills Nursery, Omaha, NE; 888-864-7663; naturehills.com
- Wayside Gardens, Hodges, SC; 800-845-1124; waysidegardens.com
- Rarefind Nursery, Jackson, NJ; 732-833-0613; rarefindnursery.com
- White Flower Farm, Litchfield, CT; 800-503-9624; whiteflowerfarm.com