Plant taxonomy classifies Diablo ninebark as Physocarpus opulifolius 'Monlo.' "Diablo" is a corruption of the trademark name, "Diabolo," but it is so widely used that it has become accepted. 'Monlo' is the name of the cultivar.
Traits and Best Features
Diablo ninebark shrubs reach eight to 10 feet tall with a similar spread. These multi-branched, upright shrubs are fast growers. Late-spring or early-summer bloomers, they bear white or pinkish-white flowers in June. The flowers grow in clusters that will remind you of those on spirea shrubs (Spiraea japonica). The purplish foliage of Diablo ninebark plants (with a touch of red here and there) earns them the nickname, "purple ninebarks" or "purple-leafed ninebarks." An increase in red color and a hint of bronze added to the purple in the leaves make them even more attractive in the fall. Mature branches have a peeling bark the way some birch trees (Betula) do, making the plants useful for injecting visual interest into your landscaping for winter.
Diablo ninebark's main feature is its purplish leaves, setting it apart from the species plant, which has green leaves. Some of this shrub's leaves may green up a bit during hot weather, but the color is a dark green (which is still plenty dark enough to set Diablo ninebark apart from most other shrubs). With flowers in spring, dark foliage in summer, fall foliage in autumn, and peeling bark year-round, there is never a season in which this bush has nothing to offer
Planting Zones, Sun, and Soil Needs
One of Diablo ninebark's selling points is its flexibility. Although it will flower better in full sun to partial sun in the North (give it a little shade in the South), it tolerates partial shade. Likewise, while Diablo ninebark will perform best in a well-drained soil that is kept evenly moist, it is relatively good at tolerating wet soil (the species is sometimes listed as a wetland plant in the wild) and clay. It even tolerates some drought.
Diablo is not the only type of ninebark widely available at garden centers. Other kinds, all of which can be grown in zones 3 to 8, include:
- 'Little Devil,' which has dark leaves, like those on Diablo.
- 'Dart's Gold,' which bears golden foliage.
- 'Coppertina,' aptly named for its coppery-colored leaves.
- 'Nana,' a dwarf variety (five feet by five feet) with green leaves.
- 'Seward,' which is usually sold as "Summer Wine." It is a cross between Diablo and Nana. This bush takes its size from Nana and its leaf coloration from Diablo. The leaves are also deeply cut.
- "Tiny Wine," which is even smaller (three to four feet in both height and spread). It is another dark-leaved type.
Uses for Shrubs, Companion Plants, and Care Tips
Many gardeners grow Diablo ninebark shrubs as specimen plants in their landscaping. Massed along a border, they can form a loose privacy hedge for summer. Their foliage color goes well with plants that are golden or chartreuse, such as Gold Mops false cypress (Chamaecyparis pisifera 'Gold Mop').
Prune the bush to shape it (if you do not like its natural shape) after blooming since Diablo ninebark blooms on the prior year's wood. Or if you do not mind sacrificing flowers for one year to make your plant more compact, you can prune it back to ground level in winter. (This is called rejuvenation pruning). But many prefer to let these bushes go wild rather than pruning them into human-chosen shapes. Red seed pods can succeed the flowers in fall, but only if you spare the pruning shears and spoil your shrubs with the freedom to grow as they naturally would.
Origin of the Names
Its devilish cultivar name (via Spanish) refers to the dark purplish leaves that this shrub bears in spring, with dark colors being loosely associated with the devil.
The common name "ninebark" comes from the plant's peeling bark. Several shades of brown are displayed as it peels. As an outer layer of bark peels, a new layer with a slightly different color is revealed. The "nine" refers to the number of such layers, although nine seems to be an arbitrary figure.