Friends say that I never met a plant I didn’t like. That may be true, but my deepest regard is reserved for precious few in Flora’s kingdom. One is purple-leaved Eastern ninebark (Physocarpus opulifolius ‘Diablo’, syn. ‘Monlo’ and ‘Diabolo’). This stunning multistemmed deciduous shrub has it all: superlative color, appealing form, and good looks that last all year long. It’s adaptable in terms of soil conditions and is drought resistant and easy to grow, which it does eagerly and, better yet, rapidly.
The main claim to fame for ‘Diablo’ (which means “devil” in Spanish) is the deep burgundy color of its maplelike foliage. It bears the most deeply hued leaves of any woody plant in my garden. And unlike the others, it doesn’t get greener with the onset of summer heat and humidity in my USDA Hardiness Zone 6 Connecticut garden—though farther south it might. Instead, the leaves on mine are almost black by midsummer. That color veers toward bronzy red by the time the leaves fall in late November.
‘Diablo’ also has an exquisite form, like a perfect fountain. Plants reach 10 feet high and 10 feet wide in four or five years. But if you need a smaller specimen, cutting ‘Diablo’ to the ground in early spring will result in a flush of even darker foliage and, of course, a more compact shrub.
Even in winter ‘Diablo’ has something to add. Like its parent—plain old Physocarpus opulifolius—the bark of this German selection of a North American native exfoliates in so many layers that it was dubbed ninebark. ‘Diablo’ also boasts pink-tinged white flowers, which appear in June in clusters about 2 inches across. I like them better as they go to seed and redden.
This shrub’s foliage really pays the rent in a mixed border, serving as the perfect foil for anything gold, pink, or silver. Blue looks good against it, too, as do chartreuse and red. ‘Diablo’ would also make an outstanding hedge. Plants prefer well-drained, acidic soil in full sun, but mine, which is in lightly amended clay and part sun, is no slacker. It’s said to tolerate poor soil and thrives in Zones 3 to 7. It has won loads of awards, from the Royal Horticultural Society and the Pennsylvania Horticultural Society, among others. In other words, this ‘Diablo’ is a saint.