American Arborvitae (Thuja occidentalis) is a widely recognized evergreen conifer belonging to the Cupressaceae family, which includes cedars and cypresses. It is botanically classified under the genus Thuja and species occidentalis. This species is native to eastern North America and has been cultivated for centuries due to its hardiness and practical value in landscaping. It is one of the few conifers native to the northern United States and southeastern Canada.
In addition to “American Arborvitae,” this tree is also commonly known as Northern White Cedar, Eastern Arborvitae, and simply White Cedar. The name “arborvitae” means “tree of life,” a term given by early French explorers who recognized the tree’s medicinal properties—particularly its high vitamin C content, which helped prevent scurvy during long expeditions.
American Arborvitae is easily identified by its narrow, pyramidal shape and dense, fan-shaped sprays of scale-like foliage, which ranges in color from light to medium green. The foliage often takes on a yellow-brown tint in cold winter conditions. The bark is reddish-brown and peels in vertical strips, adding texture to mature trunks. Small, upright cones form in fall, measuring about half an inch long. These trees are typically symmetrical and tidy in appearance, making them visually appealing in formal plantings.
In terms of growth rate, American Arborvitae grows slow to moderate, averaging 12 to 24 inches per year depending on soil and climate conditions. It can eventually reach heights of 40 to 60 feet in the wild, though cultivated varieties are often kept much smaller. With proper care, the tree can live for 70 to over 150 years, especially in native woodland settings.
American Arborvitae is naturally found across the northeastern United States, the Great Lakes region, and southeastern Canada, where it thrives in cool, moist environments. It grows well in swamps, bogs, and along limestone cliffs, showing a preference for calcareous soils but also adapting to a variety of soil types in cultivated settings.
The tree is best suited to USDA Hardiness Zones 2 to 7, making it one of the most cold-tolerant arborvitae species available. This wide range allows it to be planted successfully in regions with harsh winters and relatively short growing seasons. Its adaptability and native status make it a reliable choice for both wild and cultivated landscapes.
Other notable facts about American Arborvitae include its cultural and ecological importance. Indigenous peoples historically used its wood and foliage for medicinal and practical purposes. The rot-resistant wood is lightweight yet durable, ideal for making canoe frames, fence posts, and shingles. The tree also provides valuable cover and nesting sites for birds, particularly in winter when few other evergreens offer protection.
Landscape uses of American Arborvitae include:
- Tall privacy screens or windbreaks
- Wildlife habitat or naturalistic plantings
- Formal hedges in urban or suburban landscapes
- Specimen trees in larger yards or parks
- Foundation plantings in colder climates
- Evergreen structure in mixed borders
- Restoration projects in native plant communities
- Shelter for birds and small animals during winter
Common problems associated with growing American Arborvitae (Thuja occidentalis)
- Deer browsing
– Highly attractive to deer, especially in winter
– Can cause severe damage or complete defoliation of lower branches - Winter burn
– Foliage may turn brown or bronze due to cold winds and sun exposure
– Often appears on the south and southwest sides of the tree - Root rot
– Occurs in poorly drained or consistently wet soils
– Leads to yellowing, wilting, and potential tree death - Drought sensitivity
– Shallow roots make it vulnerable to prolonged dry conditions
– Inner needles may brown and drop during drought stress - Pest infestations
– Can be affected by bagworms, spider mites, and arborvitae leafminers
– Symptoms include browning, thinning foliage, and small webbed sacs - Fungal diseases
– Prone to tip blight and canker diseases, especially in humid conditions
– Results in dieback of branch tips and browning of foliage - Improper pruning
– Cutting into old wood can result in permanent bare spots
– Over-pruning may distort its natural pyramidal shape - Snow and ice damage
– Heavy snow or ice can bend or break branches
– Can lead to a misshapen tree if not corrected early - Salt damage
– Sensitive to road salt and saline irrigation water
– Leads to browning at the edges or tips of foliage - Crowding and poor air circulation
– Planting too close together increases disease risk
– Reduces light penetration, causing interior browning
Cultivation of American Arborvitae (Thuja occidentalis)
Site Selection
– Choose a location with full sun to partial shade.
– Full sun promotes dense foliage and a stronger structure.
– Avoid very shady spots, which may cause thinning and weak growth.
Soil Preferences
– Thrives in moist, well-drained soil, but can tolerate clay, loam, or even rocky soils.
– Prefers slightly alkaline to neutral pH, especially in areas with natural limestone.
– Avoid planting in locations with standing water or soggy conditions.
Watering Needs
– Requires consistent watering during the first two years for root establishment.
– Once mature, it is somewhat drought-tolerant but still benefits from deep watering in dry spells.
– Shallow roots make it more prone to drying out than other conifers.
Mulching
– Apply a 2–3 inch layer of mulch around the base to retain moisture and regulate soil temperature.
– Keep mulch 2–3 inches away from the trunk to prevent rot and rodent damage.
– Organic mulches like bark or wood chips work best.
Fertilization
– Fertilize in early spring with a balanced, slow-release fertilizer (e.g., 10-10-10).
– Avoid over-fertilizing, as it can cause leggy growth and stress the tree.
– Mature trees typically need little to no fertilizer if growing in healthy soil.
Planting Time
– Spring and early fall are the best times to plant for strong root development.
– Avoid planting in extreme summer heat or frozen ground conditions.
– Water thoroughly at planting and keep soil consistently moist for several weeks.
Spacing
– Space trees 3–5 feet apart for hedges or screens, depending on the desired density.
– Allow at least 5–6 feet from buildings or fences for air circulation and mature growth.
– Proper spacing helps prevent fungal diseases and promotes better form.
Pruning Practices
– Minimal pruning is needed due to its natural pyramidal shape.
– Only remove dead, damaged, or diseased branches as needed.
– Avoid cutting into old wood, which may not produce new growth.
Winter Protection
– In colder regions, protect young trees with burlap wraps to prevent winter burn and snow damage.
– Water well in late fall before the ground freezes to hydrate the roots.
– Anti-desiccant sprays may help reduce foliage drying.
Pest Management
– Monitor for bagworms, spider mites, and arborvitae leafminers.
– Insecticidal soap or horticultural oils can help control outbreaks.
– Encourage birds and beneficial insects as natural predators.
Disease Prevention
– Ensure good air circulation by spacing trees properly and avoiding overcrowding.
– Avoid overhead watering, which increases the risk of fungal diseases like tip blight or root rot.
– Remove any infected plant material promptly.
Deer Protection
– American Arborvitae is highly susceptible to deer browsing, especially in winter.
– Use fencing, netting, or repellents in areas with high deer populations.
– Repeated browsing can permanently deform or kill young trees.
Companion Planting and Design Use
– Works well with other native shrubs, ornamental grasses, and woodland perennials.
– Use as a natural screen, windbreak, or foundation plant.
– Combines beautifully in formal landscapes, cottage gardens, and wildlife-friendly settings.