Physocarpus opulifolius

Ninebarks haven't always received the most respect from members of the nursery industry.

Michael A. Dirr, NMPRO contributing editor and University of Georgia professor, had a few words to say about Physocarpus opulifolius in his "Manual of Woody Landscape Plants: Fifth Edition."

"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."

But keep in mind that a lot has happened since this book was published in 1998. Ninebark breeders in the United States and abroad have been busy tinkering with this deciduous shrub.

Dark foliage

Monrovia Growers in Azusa, Calif., introduced Diabolo ('Monlo') in 1999. The plant was selected for its reddish-purple (almost-black) leaves, which contrast well with the plant's white spring flowers. This cultivar has also proven to be excellent for breeding, as three new cultivars available list Diabolo as a parent.

Summer Wine ('Seward'), introduced by Spring Meadow Nursery in Grand Haven, Mich., is a cross between Diabolo and 'Nana.' Summer Wine has dark foliage and a compact growing habit, listed as maturing at 4-6 feet high and wide, when typical P. opulifolius reaches 8-10 feet high.

The latest ninebark from Spring Meadow is Coppertina ('Mindia'), bred in France for its orange-copper spring foliage that fades to red with maturity. It's a cross between Diabolo and 'Darks Gold,' a yellow-leaf variety. Coppertina was available on a limited basis in 2005 with full release by Spring Meadow in 2006.

Next year Bailey Nurseries in St. Paul, Minn., is releasing 'Center Glow,' a cross between Diabolo and 'Darts Gold.' While its parentage is the same as Coppertina, it's much different in leaf color.

The foliage of 'Center Glow' emerges golden and quickly changes to burgundy. This gives the plant a dramatic appearance as the colors contrast against each other.

'Center Glow' was bred by Harold Pellett, executive director of the nonprofit Landscape Plant Development Center in Mound, Minn. (Pellett also put together the ninebark collection at the Minnesota Landscape Arboretum, which Dirr mentioned.)

More improvements

Ninebarks are considered northern plants and rarely perform well south of USDA Hardiness Zone 7. However, Pellett has heard reports of good performance by 'Center Glow' in Oklahoma.

He hopes to breed ninebarks more suited to hotter climates, as well as more dwarf varieties.

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Specifics

Name: Physocarpus opulifolius

Common name: Ninebark.

Description: Deciduous shrub 8-10 feet high with white spring flowers, red fruits and exfoliating bark. Cultivars are available with foliage ranging from dark purple to red to gold.

Culture: Foliage color is most dramatic in full sun. It performs best in cooler climates and in well-drained soils.

Propagation: Easy from cuttings.

Hardiness: USDA Hardiness Zones 2-7.

For more: Monrovia Growers, 18331 E. Foothill Blvd., Azusa, CA 91702; (800) 999-9321; fax (626) 334-3126; www.monrovia.com. Spring Meadow Nursery, 12601 120th Ave., Grand Haven, MI 49417; (800) 633-8859; www.colorchoiceplants.com. Bailey Nurseries, 1325 Bailey Road, St. Paul, MN 55119-6313; (651) 459-9744; fax (651) 459-5100; www.baileynursery.com. Harold Pellet, Landscape Plant Development Center, P.O. Box 444, Mound, MN 55364; (952) 443-1400.

- Todd Davis