Northern white-cedar (Thuja occidentalis): what the agencies record

This page reports what US federal publications say about one tree. It does not identify trees from descriptions or photos and does not say what should be done with any tree. The family overview, tree species in the agency records, explains the sources and holds the comparison table.

At a glance

Item	What the source records
Scientific name	Thuja occidentalis L., cypress family
Other names	Eastern white-cedar, arborvitae and swamp-cedar (Silvics); USDA PLANTS lists arborvitae, eastern white cedar and northern white cedar
Native status, USDA PLANTS	Native in Canada and in the lower 48 states
Size, Silvics	Commonly 12 to 15 m (40 to 50 ft) tall and 30 to 60 cm (12 to 24 in) in diameter at maturity; record tree in Michigan 175 cm (69 in) in diameter and 34 m (113 ft) tall
Maximum age, Silvics	400 years or more in swamps or other lowland sites
Green weight of the wood, NRS-38	36 lb per cubic foot, without bark

Native range

The Silvics of North America handbook (Agriculture Handbook 654, volume 1, 1990) says the main range of northern white-cedar runs through the southern part of the eastern half of Canada and the adjacent northern United States. It extends west from Anticosti Island in the Gulf of St. Lawrence to the southern part of James Bay and through central Ontario to southeastern Manitoba, south through central Minnesota and Wisconsin to the southern tip of Lake Michigan, then east through southern Michigan, southern New York, central Vermont and New Hampshire, and Maine. The handbook also lists local populations in northwestern Ontario, west-central Manitoba, north-central Illinois, Ohio, southern New England and the Appalachians from western Pennsylvania south to western North Carolina and eastern Tennessee. It describes the tree as growing on rocky cliffs throughout its range, and calls it a widely planted ornamental that also provides shelter and browse in winter deeryards.

Size, cones and roots

Silvics says infrequently the tree reaches 21 to 24 m (70 to 80 ft) tall and 120 to 150 cm (48 to 60 in) in diameter, with maximum reported dimensions of more than 30 m (100 ft) and 180 cm (72 in). It says the tree generally grows more slowly and attains less height than its associates, especially in swamps, and commonly has a curved butt and poor form there. The tree is monoecious, with tiny conelike male and female flowers usually on separate twigs. Ripe cones are pale cinnamon brown, oblong and 8 to 13 mm (0.3 to 0.5 in) long, ripening from August to September in northern Michigan.

On roots, the handbook says that after the seedling stage the tree generally develops a shallow, wide-spreading root system and that natural root grafts are fairly common. Seedlings grown in different media changed from a long taproot with few laterals to shorter, thicker roots with many laterals as the moisture-holding capacity rose.

Wood

The Wood Handbook (FPL-GTR-282, 2021) says the heartwood of northern white-cedar is light brown and the sapwood nearly white and usually narrow. The wood is lightweight, rather soft, low in strength and shock resistance, with low shrinkage on drying, easily worked, and a very decay-resistant heartwood. Production is greatest in Maine and the Great Lakes states. Uses it lists are poles and posts, outdoor furniture, shingles, cabin logs, lumber, water tanks and boats. Silvics names rustic fencing and posts as the principal commercial uses.

Wood Handbook figure	Green	At 12% moisture content
Specific gravity (Table 5-3b)	0.29	0.31
Modulus of rupture, lbf per square inch (Table 5-3b)	4,200	6,500
Side hardness, lbf (Table 5-3b)	230	320
Moisture content of green wood (Table 4-1)	Not published for this species	Not applicable

The green weight of the wood is in the NRS-38 table, the same figure used in the log weight calculator.

Damaging agents the handbook names

Silvics (1990) says northern white-cedar is relatively free from serious insect injury and has few serious diseases as a forest tree.

Water and weather. On wet sites, restricted soil aeration from abnormally high water levels, caused mainly by wetland road crossings and beaver damming, usually reduces growth and may kill entire stands. Snow and ice break limbs and stems, and winter weather, deicing salts and drought are listed as agents that turn the foliage yellow or brown. The handbook says the oldest foliage turning rusty red in fall is a natural shedding of branchlets.
Fire. The handbook says the tree is highly susceptible to fire damage because its bark is thin with a high oil content and its shallow roots are easily damaged even by light ground fires.
Insects. Carpenter ants and leafminers are called probably the principal insect pests. The black carpenter ant is recorded as commonly reducing the timber value of large trees, and the arborvitae leafminer as severely damaging stands in Maine. For ornamentals it names the bagworm, juniper scale and spruce spider mite, and in nurseries the Fletcher scale, arborvitae aphid and arborvitae weevil.
Foliage fungi. Phomopsis juniperovora and Didymascella thujina among the main organisms causing seedling diseases, with the first also blighting foliage and shoots under humid conditions.
Butt and root rots. Poria subacida, balsam butt rot (Tyromyces balsameus) and red-brown butt rot (Phaeolus schweinitzii). The handbook says they mainly attack old or damaged trees, that fruiting bodies seldom appear on living trees, and that the most common outward sign of rot is woodpecker holes.
Animals. Winter browsing by white-tailed deer on seedlings and saplings in the Lake States, snowshoe hares, and porcupines that feed on foliage and girdle stems and branches.

The guide on reporting a pest in the United States gives the office that takes sightings of regulated pests, and pests and diseases by country sets out which ones agencies regulate. Who may apply pesticides is in pesticide licences by country.