Smoke bush, Cotinus coggygria, is a deciduous shrub that's also commonly known as royal purple smoke bush, smokebush, smoke tree, and purple smoke tree. Smoke bush is often used as a garden specimen thanks to its beautiful purple-pink smokey plumes and the purple leaves found on some cultivars.
Smoke bush has an upright, multi-stemmed habit. The leaves are waxy green except for those cultivars with purple leaves, and are 1 1/2 to 3 inches long, ovate in shape. They turn yellow, orange, or purplish-red in fall, depending on variety. The name "smoke bush" derives from billowy hairs attached to the flower clusters which remain in place through the summer, turning a smoky pink to purplish-pink as the weeks progress. Purple smoke bush is dioecious, meaning it has staminate and pistillate (male and female) flowers borne on different individuals.
Smoke bush is often used as an individual specimen plant, and in larger landscapes, it can be massed or planted as an informal screening hedge. The plant is drought-tolerant, so it's useful in xeriscaping and other applications where water conservation is important.
|Botanical Name||Cotinus coggygria|
|Common Names||Smoke bush, purple smoke bush, smoke tree, smoketree, European smoketree, Eurasian smoketree, Venice sumach, dyer's sumach|
|Plant Type||Deciduous shrub|
|Mature Size||10 to 15 feet high, similar spread|
|Sun Exposure||Full sun|
|Soil Type||Prefers infertile loam, but tolerates all soils except wet, poorly drained soils|
|Soil pH||Tolerates both acidic and alkaline soils|
|Bloom Time||Late spring to mid-summer|
|Hardiness Zones||4 to 11|
|Native Area||Southern Europe to central China|
|Toxicity||Poisonous to humans|
Watch Now: How to Grow and Care for a Smoke Bush
Care For Smoke Bush
Smoke bush should be planted in full sun, but it does well in almost any soil type and most any pH level. The ideal circumstance is slightly sandy loam, but they also do well in rocky soils. In zone 5, plant them in slightly sheltered locations to protect from winter winds. When grouping plants, they should be spaced 10 to 15 feet apart.
Young plants should be watered deeply and regularly, but once established, smoke bush has good resistance to drought. Mulch the base of the shrubs with wood chips, or bark mulch, to keep weeds away and soil moist.
The only mandatory pruning is to remove dead or damaged wood, but the shrubs will tolerate hard pruning to shape them or rejuvenate them.
In part shade conditions, foliage will be sparse, requiring regular pruning to keep the plants dense.
Smoke bush does well in nearly all soil conditions provided the soil is well-drained. It does not tolerate damp, soggy soils.
Once established, smoke bush has good tolerance for dry conditions. When getting established, the shrubs require regular watering, but mature plants thrive nicely if watered moderately every 10 days during the active growing season.
Temperature and Humidity
Smoke bush does best in moderate temperatures and average to dry humidity levels. In moist, very warm climates, fungal diseases are often a problem. In colder climates, winter winds can damage the plants, so they should be planted in sheltered conditions in these regions.
Smoke bush does not require much in the way of feeding. Fertilize them in spring with a layer of compost. An annual application of organic plant food may be called for if the shrubs are not growing vigorously. The main needs are for nitrogen to fuel the growth of foliage.
Is Smoke Bush Toxic?
Smoke bush's sap can irritate the skin, as its leaves may be poisonous to humans.
Symptoms of Poisoning
Skin irritation is the most common response that people have to Smoke bush.
Smoke Bush Varieties
- 'Daydream' is a good green-leaved cultivar with dense, creamy blooms. It is a somewhat smaller plant, growing to a maximum of 10 feet wide and tall
- 'Nordine' is a very hardy purple-leaved variety. It has yellow-orange fall foliage
- 'Royal Purple' is a common purple-leaved form with dark foliage and purple-red "smoke"
- 'Velvet Cloak' is another dark purple-leaved form; it has dramatic orange-red fall color
Pruning needs are minimal with smoke bush. You can prune anytime to remove damaged branches, but spring is the best time to prune in order to shape the shrub or rejuvenate it. If you wish to avoid the messy flowers, prune heavily in spring to remove the flowering wood.
If you wish to encourage a tree-like growth habit, prune away all but one central leader stem, and keep pruning away any stems that reappear. A bushier shrub can be obtained by cutting all stems down to ground level in late winter for the first two or three years.
Propagating Smoke Bush
Propagation of smoke bush is by cuttings and seeds. A leafy stem stripped of its lower leaves and embedded in a growing medium will easily root itself.
How To Grow Smoke Bush From Seeds
Seeds are teeny-tiny, and must be soaked in water for 24 hours before planting, changing water once. Air dry. Plant 3/8" into sandy soil.
Potting and Repotting Smoke Bush
Smoke bush has a nicely contained fibrous root system and is easy to transplant. Start by root-pruning the shrub several months before you plan to move it, by digging a 12-inch to 24-inch circle, 14 inches deep, around the plant's base. At transplant time, dig down around the tree 12 to 14 inches, then lever the root ball out of the ground and move the shrub to its new location.
Be sure you use good, feritlized potting soil, and mix in some sand and compost. Be sure to place your potted smoke bush in a sunny area, and water fully but infrequently.
Be careful not to over water or over fertilize your smoke bush this time of year. Use around 3" of mulch around the bases of plants
Common Pests (or Diseases)
The oblique-banded leafroller, a native North American pest that feeds on a wide range of plants, can be a problem with smoke bush.
If soils are not well-drained, smoke bush is very susceptible to verticullum wilt—a browning of the leaves caused by the fungus Verticillium. It can also get scabs and leaf spot, a fungal condition prevalent in warmer weather. If you live in the eastern United States, watch out for stem canker.
Cotinus Coggygria. Missouri Botanical Garden
Hall, Carol W., and Norman E. Hall. Timber Press Guide to Gardening in the Pacific Northwest. Timber Press, 2008