By: Vicky Congdon
If you've got a spot in the yard for something really eye-catching and a little different, consider smoke bush (Cotinus). The colorful foliage of this unusual ornamental is attractive throughout the season, but really heats up in fall, deepening to brilliant shades of purple, red, or orange-yellow, depending on the variety. As the large, loose clusters of tiny greenish flower blossoms fade, the flower stalks get longer and by midsummer are covered with fuzzy purple or pink hairs. These feathery trusses look like puffs of smoke -- hence the common name smoke bush or smoke tree. Even with these showy blossoms and vibrantly colored leaves, smoke bush is an easy plant to work into the landscape because it combines so readily with other perennials.
Striking as a single plant, it is spectacular in a group. "This plant is definitely underused," says Alan Summers, owner of Carroll Gardens, a retail and mail-order nursery in Westminster, Maryland. "It just marches out of here. Once people see it, they take it home."
Smoke bush is hardy in virtually all regions of the United States from USDA Hardiness Zone 4a through 11. However, it's most prized in the colder areas where few other plants can compete with its dramatic foliage color.
You'll see smoke bush described in catalogs and garden references as both a shrub and a tree. Left to its natural inclinations, it will grow into a tree. The Eurasian species, Cotinus coggygria, reaches a height of 15 feet; C. obovatus, a native of the southeast, is even taller, reaching 25 to 30 feet. In the garden, smoke bush can be trained as a single- or multi-trunked tree. "But that's a lot of work," says Summers. Treat it as a large shrub, he advises, and you'll have a full, nicely rounded plant that's easily maintained.
Another recommendation from Summers is to start with a named variety. Bill Funkhouser, assistant director of horticulture at Wayside Gardens in Hodges, South Carolina, agrees. "Although the American native has good fall color and I'd like to see it grown more," he notes, "you want the best show you can get out of your plants, and a selected variety will give you the best blooming, the best form and the most consistent coloration."
There are several fine selections of C. coggygria available; the shades and intensity of the colors can vary somewhat depending on soil conditions and climate.
'Velvet Cloak' has reddish purple leaves that hold their color well through the season, turning to a brilliant deep red in fall. It produces many purply pink "smokes." "It's just spectacular all season long," says Summers.
The leaves of 'Royal Purple' start off red, deepening to a rich purple that stays vibrant through the summer, then changing to shades of red, yellow, and orange in fall. "It's a little more compact than some of the other cultivars," notes Funkhouser, "and the foliage doesn't fade." The blossom clusters are purple.
The hardiest of the purple-leaved smoke bushes, 'Nordine', has large, pinkish blossoms and purplish red leaves that turn a rich green or orange-yellow in fall. "By fall, the blossom clusters are huge and showy, and the leaves have good color," says Summers.
Hardier still are the green-leaved smoke bushes, and 'Daydream', with blue-green leaves that turn red-orange in fall, is a very attractive variety. Its pink smokes stay showy for a long period of time.
A pink hybrid, 'Grace', is now available in the United States. A cross between Cotinus obovatus and 'Velvet Cloak,' it has won several awards in England. "The 4- to 6-inch leaves are about 1/3 larger than those of other cultivars and the huge smokes are almost a fluorescent pink," says Rick Eggimann, owner of Hollandia Gardens, wholesale growers in Hubbard, Oregon. The purplish red foliage turns red-orange in fall. 'Grace 'is a very vigorous grower, however, and tends to be lanky rather than bushy, he notes. It requires some vigilance with the pruning shears during the growing season to keep it looking good.
Whether you plant one smoke bush or group several together, choose the location carefully. "It's too large to be a foundation plant, and I wouldn't simply park it in the middle of the lawn as a single specimen, either," says Alan Summers. "Think of it as a lilac in terms of placement. It's a good screening plant and works well on the edge of the property, perhaps dressed down with another shrub.