Smokin'! This is the first word that comes to mind when I see this unusual plant in bloom. What could be an ordinary large shrub or small tree becomes puffy in summer with these ethereal plumes. They last a long time. Ours has been in bloom for the past month and is just barely beginning to fade. Even as they wither their attractive appeal continues. Eventually, the spent flowers become so fragile that they break away and gather around like miniature tumble weeds.
Just when C. coggygria 'Purpureus' takes a break from its show, autumn arrives and the leaves turn shades of red, orange and yellow, and we enjoy it until the last leaf drops in winter. Once dormant, pruning and shaping is easy to evaluate. If the form is attractive, no pruning is necessary, but sometimes the smoke tree can get a little wild, sending out shoots seemingly haphazardly. I tend to remove them unless the limbs are pointing in a desirable direction. Other gardeners may choose to cut it back hard and allow it to regrow, maybe taking on another form.
I had difficulty capturing the true color of the leaves, but Cal Poly's SelecTree has helpful images. The leaves (shown below) are certainly green...dark green...and have a slight purple tint to them. By comparison, C. coggygria has brighter green foliage and tannish flowers. There are so many cultivars coming on the market that designers can choose chartreuse (C.c. 'Golden Spirit') or deep purple foliage (C.c. 'Royal Purple'), as examples.
Nurseries favor carrying the named cultivars for the stellar coloring. Typically found in 5 gallon, 15 gallon, or larger containers, their form is either multi-trunk or can sometimes be found as a standard (single trunk). The single trunk specimens do not easily retain their form, as they prefer to branch out with low limbs. This is what makes them more suitable as large shrubs, but with a little effort, smoke trees can be used as small patio trees.
facts
Botanical Name: Cotinus coggygria 'Purpureus'
Cotinus: Greek for kotinus for olive (possibly for the leaf color?)
Coggygria: Greek for kokkujia for smoke tree
Purpureus: Purple, probably for the flower and/or leaf tint
Common Name: Smoke tree
Family Name: Anacardiaceae
Origin: Southern Europe to eastern China
design considerations
Positioning: Background, forest edge, courtyard, raised planter, residential/commercial, under power lines
Garden Themes: Mediterranean/dry, woodland, cottage/informal, rain
Uses: Specimen, border, mass, accent, container, green stormwater infrastructure (elevated slopes and uplands only)
identifying characteristics
Type: Deciduous shrub or small tree (multi-trunk or standard)
Form: Round, upright, spreading
Texture: Medium (fine when in bloom)
Size: 15' tall and wide
Outstanding Feature(s): Flower, fall foliage
Bark: Dark gray, exfoliating
Leaf:
Type: Simple
Arrangement: Alternate
Shape: Obovate to ovate
Margin: Entire
Color: Dull dark green with red/purple tint turning red, orange or yellow in Autumn
Surface: Smooth, glabrous
Flower: Summer. Burgundy pink panicle fading to tan. Fuzzy/smoky appearance
Fruit: Summer. Tan drupe
cultural requirements, tolerances & problems
Sunset Zones: 2-24
USDA Zones: 4-9
Light: Full sun
WUCOLS SF Bay Area Hydro Zone: Low
Soil:
Texture: Sand, loam, clay, well composted, well-drained
Moisture Retention: Allow to completely dry for extended periods
pH: Highly acidic to highly alkaline
Tolerances: Drought, heat, heavy soil, deer, armillaria
Problems: May readily reseed but uncommon; may produce lanky growth; flower drop messy by patios/pools; low topical toxicity
Insects: Leaf rollers
Disease: Leaf spot, scab, verticillium
citations & attributions
Gilman, E.G., Watson, D.G. (1993). Cotinus coggygria 'Purpureus': 'Purpureus Smoketree. Department of Agriculture Forest Service. Accessed on July 21, 2021, from https://hort.ifas.ufl.edu/database/documents/pdf/tree_fact_sheets/cotcoge.pdf.
NC State Extension. "Cotinus coggygria." North Carolina State University, Raleigh. Accessed on July 28, 2021, from https://plants.ces.ncsu.edu/plants/cotinus-coggygria/.
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
SelecTree. UFEI. "Cotinus coggygria 'Purpureus' Tree Record." 1995-2021. Cal Poly State University, San Luis Obispo. Accessed on July 21, 2021, from https://selectree.calpoly.edu/tree-detail/437.
Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on June 28, 2021.
Photos:
All photos by TELCS.