Thuja occidentalis - American Arborvitae
Family: Cupressaceae

Hear the scientific name

Thuja occidentalis is a common evergreen shrub. American Arborvitae is often pyramidal in shape, and useful for foundations and entranceways or as a privacy screen when in rows.

Alternate common name: Eastern Arborvitae

F   E   A   T   U   R   E   S
  form2 form Form

-small, medium, large, or very large evergreen shrub, depending upon cultivar

-often maturing at about 20' tall x 8' wide in urban landscapes; however, the species form and larger cultivars can slowly get much bigger over time, to 50' tall x 15' wide, while dwarf cultivars can mature at 3' in height with a slightly wider width

-upright pyramidal, upright columnar, or rounded growth habit, depending upon cultivar

-slow growth rate

foliage2 foliage Foliage

-sprays of scales

-evergreen

-old foliage abscising in autumn, new foliage yellows or browns in winter but remarkably turns back to dark green in Mar.

-scented when cut or bruised

-dark green, but can vary depending on cultivar

Flowers

-insignificant (Apr.)

Fruit
fruit

-small cones, often not noticed (Sept.)

Twig
twig

-brown, covered with green scaly foliage

trunk Trunk

-exfoliating to a brownish red

-often hidden by foliage

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Culture

-full sun to partial sun

-prefers a moist, well-drained, loamy soil in full sun, but tolerates soils that are poor, rocky, clay, compacted, dry, and of various pHs extremely well, and is very urban tolerant to heat, drought, humidity, and pollution; however, not tolerant of shady situations

-propagated primarily by rooted stem cuttings

-one annual pest (bagworms, which cause minor to major feeding damage to the new foliage) and one long term disease (heartwood rot of the interior wood, which leads to a decline in vigor with maturity) are noteworthy; several other potential diseases and pests occur rarely

-abundantly available in B&B or container forms

-very prone to having its vertical branches permanently separated in the upper canopy when under ice or wet snow loads, due to the very flexible and lightweight wood with dense evergreen foliage that catches and retains the heavy winter precipitation

distribution map

Hardiness

-zones 3 to 7

Origin

-native to Eastern U.S.

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Assets

-very urban tolerant evergreen shrub

-foliages to the ground even at maturity

-responds well to continuous shearing (although it is rarely needed, except when it exceeds the height or width for which it was originally intended)

-cold hardiness (to zone 3)

Liabilities

-winter evergreen foliage color is often an unattractive yellow-brown

-prone to bagworms and their feeding damage

-prone to branch separation under snow and ice loads

-widens at its base with age, or separates into several leaning but divergent canopies with age

-does not recover from severe pruning (where the bare stems are exposed, although side branches may slowly envelope the dead stems)

-interior foliage noticeably sheds in autumn

Function

-foundation, hedge, entranceway, privacy screen, non-thorny barrier, or specimen shrub

-often overused

Texture

-medium texture

-thick density

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Varieties and Cultivars - Search OSU PlantFacts for additional plants in this species

Alternates

-evergreen shrubs, especially those that are columnar, upright oval, or pyramidal

 


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