Smoketree

Cotinus, known as Smoketree, is a genus of woody plants appreciated for their “smoky” flower plumes and for their leaf color, especially in autumn. Michael Dirr in his famous Manual of Woody Landscape Plants says “…it may be the best of all American shrub/trees for intensity of color.” Two species and many selections and hybrids offer leaf colors ranging from rich blue-green, maroon red, purple-red and yellow-gold; and the fall colors are even more vibrant. With the current passion for new plants, it is curious that Smoketree is not seen more often in our western landscapes.

The species Cotinus obovatus (americanus), native from Alabama to Texas, is only hardy to zone 5 but I know of an old one in Boulder that is 16’x18’. The flowers are not quite as showy as the European species, but the fall color is brilliant, turning vivid red, yellow, and orange. The main season leaf color for American Smoketree is an attractive rich blue-green. It likes our alkaline soils and is heat and drought tolerant, though it will grow faster and have better leaf color with once a week watering. This species can grow to 20’-25’ tall and has no serious insect or disease problems. The habit is loose, and can even be unkempt, so avoid over-fertilizing and over-watering. Keep any leggy growth shortened for beauty and strength, and/or remove some of the lowest branches to create a small tree look.

The other species, Cotinus coggygria (pronounced koe-gige-ri-a), is native to Europe and China. It is hardy to zone 4, grows like a big shrub to 10’-15’ and its showy, smoky pink flower panicles are 8” long or more. In truth, the individual flowers are insignificant little greenish yellow things that develop the attractive smoky effect when thousands of pinkish hairs elongate from the fading flowers. Like C. obovatus, it is adapted to dry, rocky soils, but will tolerate anything but wet soils. The books all say Smokebush wants full sun, but Dan Wise from Ft. Collins Wholesale Nursery says it looks best as an understory shrub in filtered shade. The form tends to be loose and can be improved with pruning.

Several varieties are available locally. ‘Grace’ is a hybrid between C. obovatus and C. coggygria ‘Velvet Cloak’. It can become a small tree to 20’ and is said to have leaves that are light red when young, turning blue-green. In my garden’s water-deprived conditions, the leaves are blue-green in its own shade and in full exposure, they are a dull purple edged and veined with cherry red. The pink smoky panicles can grow to 14” long and in fall the leaves turn luminous red, orange and yellow.

The most commonly available selection of C. coggygria is the very showy ‘Royal Purple’. Its foliage begins a rich maroon-red, becoming dark purple and turning a showy red-purple in fall. It makes a dramatic specimen or is effective as a background planting to highlight shorter plants with pink flowers or silver foliage. The flower panicles are also a purple red. If you can sacrifice the flowers, intensely vivid colored foliage can be produced by cutting the shrub to 4” each spring before it leafs out. It will then grow into an eye-catching 4’-5’ vase-shaped shrub.

 ‘Royal Purple’ will grow 10’-15’ tall and almost as wide. I have been growing this selection in a difficult spot for about ten years in full sun with only two waterings a year, and it is now 4’ tall and 3’ wide. It even looks good in July, making a splash of purple next to a Threeleaf Sumac.

Other selections available locally are ‘Young Lady’, selected for its ability to bloom even as a young plant, growing 8’x8’ with green foliage and turning orange/red in fall; and ‘Golden Spirit’, 8’x6’, with yellow/gold leaves that don’t scorch in sun unless grown too dry. It turns coral, gold, red and orange in fall. At least one of these varieties was available at Timberline, Echter’s, Harlequin’s Gardens, The Flower Bin and Nick’s. Many other selections and hybrids have been made.

This adaptable shrub/tree is drought tolerant, with colorful foliage and an ethereal smoky inflorescence. It was introduced to horticulture in the 1600s. It’s time we discovered it in Colorado.