The smoke tree, or smokebush, is an ornamental plant known for its striking, cloud-like plumes that give it a hazy appearance. This deciduous shrub or small tree offers multi-season interest, with vibrant foliage colors that transition dramatically from spring through autumn.
Identifying Characteristics and Name Origin
The plant’s common name comes from its spectacular summer display, which resembles a puff of smoke suspended above the foliage. This smoky effect is not the bloom itself, but the clusters of tiny flowers that failed to develop. These sterile flower stalks, known as pedicels, elongate and become covered in fine, feathery hairs after the flowers have dropped.
These airy filaments create the illusion of pink, purple, or reddish-brown haze that lasts for several weeks through the summer. The foliage provides a backdrop for the plumes, with cultivars offering leaves in shades ranging from bright green to deep purple, such as ‘Royal Purple’. In autumn, the leaves turn brilliant shades of orange, red, and scarlet.
Distinguishing the Two Main Varieties
The name “smoke tree” commonly refers to two distinct genera. The most widely cultivated species is the ornamental European Smokebush, Cotinus coggygria, native to southern Europe and temperate parts of Asia. This species is typically a multi-stemmed shrub or small tree prized for its colorful foliage and plumes.
The second plant sharing the name is the North American Desert Smoke Tree, Psorothamnus spinosus. Psorothamnus is a legume native to the arid Mojave Desert, including parts of Arizona and California. This desert variety is characterized by spiny, intricately branched stems that are nearly leafless for much of the year, giving the tree a gray, smoky appearance from a distance.
The ornamental Cotinus thrives in garden settings, while the desert Psorothamnus is adapted to extremely dry conditions and is not typically grown outside of its native range. While both share the “smoke tree” moniker, their growth habits, flowering structures, and native environments are entirely separate, making them easy to differentiate.
Cultivation and Maintenance
Cotinus coggygria is valued for its hardiness and adaptability, typically thriving in USDA zones 5 through 8. For the best foliage and plume color, the plant requires full sun exposure, although it can tolerate partial shade. Purple-leaved varieties need the strongest light to maintain their deep color and prevent the leaves from reverting to green.
The smoke tree is highly tolerant of poor or rocky soil conditions, but proper drainage is necessary to prevent root rot. It performs well in a wide range of soil pH, from slightly acidic to calcareous. Once established, Cotinus is drought tolerant, requiring minimal supplemental watering.
Pruning techniques depend on the desired outcome, as the plant is low-maintenance and does not require annual trimming. For a natural, small-tree form that maximizes the plumes, only light pruning to remove dead or crossing branches is needed in late winter. However, a technique called coppicing, or hard pruning, involves cutting the stems back significantly—sometimes to within a foot of the ground—to encourage vigorous new growth. This hard prune sacrifices the plumes for that year, but it results in larger, more vibrant leaves, often preferred for purple-leaved cultivars.