Royal Purple Smoke Tree
Cotinus coggygria 'Royal Purple'
This striking ornamental tree captivates with deep purple foliage that intensifies in fall and ethereal, smoke-like flower clusters that give the tree its common name. 'Royal Purple' offers year-round interest and serves as a dramatic focal point that few other small trees can match.
Sun
Full sun
Zones
4–8
USDA hardiness
Height
10-15 feet
Planting Timeline
Showing dates for Royal Purple Smoke Tree in USDA Zone 7
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Royal Purple Smoke Tree · Zones 4–8
Growing Details
Zone-by-Zone Planting Calendar
Complete Growing Guide
Light: Full sun (6 or more hours of direct sunlight a day). Soil: Clay, High Organic Matter, Loam (Silt), Sand, Shallow Rocky. Soil pH: Acid (<6.0), Alkaline (>8.0), Neutral (6.0-8.0). Drainage: Good Drainage, Moist. Height: 10 ft. 0 in. - 15 ft. 0 in.. Spread: 10 ft. 0 in. - 15 ft. 0 in.. Spacing: 6-feet-12 feet, 12-24 feet, 24-60 feet. Growth rate: Rapid. Maintenance: Low, Medium. Regions: Coastal, Mountains, Piedmont.
Harvesting
Small drupe, not showy, kidney shaped.
Type: Drupe. Length: < 1 inch. Width: < 1 inch.
Storage & Preservation
The Royal Purple Smoke Tree is an ornamental plant and does not require culinary storage or preservation. However, cut branches can be displayed in water indoors at room temperature (65-75°F) with moderate humidity for 1-2 weeks. For longer preservation, air-dry flower clusters in a cool, dry location away from direct sunlight; they retain their distinctive appearance for months. Alternatively, press individual leaves or flowers between paper for botanical preservation, which can last indefinitely when stored in a dry environment away from moisture.
History & Origin
Origin: S. Central Europe to China
Advantages
- +Attracts: Butterflies
- +Fast-growing
- +Low maintenance
Considerations
- -Toxic (Sap/Juice): Low severity
- -Causes contact dermatitis
Companion Plants
Lavender, Russian sage (Perovskia atriplicifolia), catmint, and ornamental grasses are the strongest partners here because they share the same basic requirements: full sun, lean soil, and sharp drainage. None of them are heavy feeders or water hogs, so they won't compete with the smoke tree's roots or push it toward the soft, aphid-prone growth that comes with over-rich soil. Sedum and Black-eyed Susan fill the ground layer without crowding, and barberry echoes the deep purple foliage without needing anything different in terms of care. In our zone 7 Georgia summers, that purple-and-silver combination with Russian sage holds its color through July and August better than almost anything else you can put together in a dry border.
Black walnut (Juglans nigra) is a hard no — it produces juglone from its root zone, a compound toxic enough to affect a wide range of woody plants, and Cotinus is not known to tolerate it well. Hostas and azaleas are a subtler problem: both want consistently moist, acidic soil in the 4.5–6.0 pH range, while 'Royal Purple' is happiest at 6.0–8.0 and on the dry side. Put them together and you'll end up overwatering the smoke tree trying to keep the hostas from crisping, which is a bad trade.
Plant Together
Lavender
Thrives in similar dry conditions and repels pests while attracting beneficial pollinators
Russian Sage
Shares drought tolerance and provides complementary blue-purple blooms
Barberry
Similar soil preferences and creates layered texture with spiny protection
Ornamental Grasses
Provides textural contrast and thrives in well-draining soil conditions
Sedum
Excellent groundcover for dry conditions and adds late-season color
Juniper
Complementary evergreen structure and similar low-water requirements
Black-eyed Susan
Drought-tolerant perennial that provides bright contrast to purple foliage
Catmint
Shares water-wise needs and attracts beneficial insects while deterring pests
Keep Apart
Black Walnut
Produces juglone which can inhibit growth and cause leaf yellowing
Hostas
Requires consistent moisture and shade, competing needs with smoke tree's preferences
Azaleas
Needs acidic, moist soil conditions that conflict with smoke tree's alkaline preferences
Pests & Disease Resistance
Resistance
Excellent disease resistance, very hardy
Common Pests
Few serious pests, occasional aphids
Diseases
Verticillium wilt (rare), generally disease-free
Troubleshooting Royal Purple Smoke Tree
What you'll see, why it happens, and what to do about it.
Leaves wilting and yellowing on one side of the plant, or entire branches dying back mid-season despite adequate water
Likely Causes
- Verticillium wilt (Verticillium dahliae) — a soil-borne fungus that colonizes the vascular tissue and blocks water movement
- Planting in a bed previously occupied by susceptible hosts like tomatoes, strawberries, or maples
What to Do
- 1.Prune out affected branches at least 6 inches below the visible dieback and dispose of the wood — don't chip it into mulch
- 2.There's no chemical cure once a tree is infected; if the whole canopy declines within a season or two, remove the tree and don't replant a Cotinus or other susceptible species in that spot for at least 4 years
- 3.Before planting, avoid beds with a known Verticillium history — choose a site with good drainage and no previous solanaceous crops
Sticky residue on leaves and stems, small clusters of soft-bodied insects visible on new growth in spring
Likely Causes
- Aphids (likely Aphis gossypii or related species) — they congregate on tender new growth and excrete honeydew, which leads to sooty mold if left unchecked
- Excess nitrogen from nearby over-fertilized lawn or beds, which pushes the kind of soft new growth aphids prefer
What to Do
- 1.Knock aphids off with a firm stream of water from the hose — do this in the morning so foliage dries before evening
- 2.A single spray of insecticidal soap (follow label dilution, typically 2 tablespoons per gallon) handles heavy infestations without doing much damage to beneficial insects
- 3.Skip the nitrogen fertilizer entirely — 'Royal Purple' doesn't need it, and feeding it just produces the lush, aphid-attractive flush you're trying to avoid
Leaf edges scorching brown or leaves dropping early in summer, no obvious pest pressure visible
Likely Causes
- Drought stress combined with reflected heat — 'Royal Purple' handles dry conditions once established, but trees under 2 years old are vulnerable during their first few dry summers in the ground
- Poorly drained or consistently wet soil, which paradoxically causes the same wilted, scorched appearance by suffocating roots
What to Do
- 1.For trees under 2 years old, water deeply once a week during dry stretches — soak to 12 inches depth rather than shallow daily sprinkles
- 2.Apply 3–4 inches of wood chip mulch in a 3-foot ring around the base, keeping it a few inches off the trunk, to hold soil moisture and buffer soil temperature
- 3.If the ground stays soggy more than 48 hours after a rain, that's a drainage problem; amend the planting site or relocate the tree — standing water through the root zone will kill it before drought will