arborvitae (Thuja occidentalis)
Nominated (2025) champion arborvitae in Carbondale at the historic Thompson House.
Species info:
Leaves: Scale-like evergreen foliage arranged in flat, fan-shaped sprays. Foliage texture is soft and fine, with colors ranging from bright yellow-green to deep emerald depending on cultivar.
Leaflets: None (foliage consists entirely of overlapping scale leaves).
Leaf Surface: Smooth, resinous, and aromatic when crushed. Scales are closely pressed and form distinct flattened fans.
Bark: Thin, reddish-brown, and fibrous, but often hidden by dense foliage. Peels in narrow vertical strips on older trunks.
Flowers: Inconspicuous; male and female reproductive structures occur on the same plant (monoecious). Male pollen cones are tiny and yellowish.
Fruit: Small, oblong cone-like structures light brown to brown, typically ⅜–½ inch long. Cones dry and open to release winged seeds.
Botanical: Thuja occidentalis
Family: Cupressaceae
Mature Height: Common landscape selections typically 10–20 feet; some cultivars remain smaller; a few larger types can exceed 20 feet
Canopy Spread: Often equal to height; 8–20 feet depending on cultivar
Foliage Type: Evergreen conifer
Tree Shape: Dense, pyramidal to rounded; many cultivars are columnar, globe-shaped, or broadly conical
Growth Rate: Moderate
Water Use: Moderate to high
Hardiness: Zones 4–6
Soil Preference: Moist, well-drained soils; tolerates a range of soil types but performs best in fertile loams; avoid compacted or excessively dry conditions
Sun Exposure: Full sun to partial shade
Wildlife Value: Provides shelter for birds and small mammals; foliage and cones offer limited food value
Wood: Light, soft, and decay-resistant; historically used for posts, small construction, and specialty woodwork
Pests/Pathogens: Generally trouble-free; may experience bagworms, spider mites, or winter burn in exposed sites; highly susceptible to deer browsing
Planting Recommendations: Conditionally recommended as it is prone to winter burn, use in protected sites
Information Sources:
Front Range Tree Recommendation List
Michael A. Dirr. Dirr’s Encyclopedia of Trees and Shrubs. Timber Press. 2011.
