Smokebush (Cotinus coggygria), is a native of Europe and Asia. Grown as either a shrub or a small tree, the species is best known for its colorful "smoke"--actually fine, colorful filaments that appear on the stalks and branches in late spring. These filaments give a mature smokebush the appearance of being enveloped in a smoky pinkish haze. Smokebush cultivars have either green or purple leaves that light up the tree in shades of red and orange in the fall. The plants can reach 10-15 feet in height, with a similar spread.
Most commercially available smokebush varieties are cold-hardy to USDA Zone 5 and a few may be viable to Zone 4. This means that the plants can generally survive in climates where temperatures can drop as low as -15 degrees Fahrenheit.
Ideally, smokebush thrives in loamy, well-drained soil that is on the acid side of the pH spectrum (3.7-6.8). However, the plants are not particularly fussy and can tolerate more alkalinity, as well as clay soil and dry or windy sites.
Shady sites tend to promote lanky growth, which can be remedied, to some extent, by pruning. To grow smokebush in the form of a small tree, locate one strong, central stalk and remove lower branches. Continue the practice as the plant matures. For a shrub, cut all stems back hard (close to the ground) for two or three years when the plant is young. This means sacrificing the beautiful "smoke" for those years, but will assure vigorous, multi-branched plants thereafter.
Smokebush responds well to massing and can be grown as a hedge. To do so, plant individual specimens close together and prune for shrubby growth as above. Prune after blooming period to maintain desired height.