1123 Thuja plicataCommon Names: western redcedar, giant redcedar, giant arborvitae, red cedar Family: Cupressaceae (cypress Family)
Western redcedar grows in a symmetrical, narrow conical shape. This is a fast growing tree with reddish, shredding bark and lower branches that eventually spread out quite far when grown in the open. Trees that grow in the forest are more columnar. Foliage has a pleasant, fruity fragrance. The scale-like leaves are tiny, and the cones are only a half inch (1.5 cm) long. The wild species, Thuja plicata becomes a very big tree, with a trunk up to 10 ft (3 m) in diameter, and reaching some 200 ft (60 m) towards the heavens. However, in gardens they rarely exceed 70 ft (21 m) in height, and many of the cultivars stay much smaller than that. 'Atrovirens' is a shrub with very dark green foliage that makes a fine hedge. Other shrub-like cultivars include the yellow leaved 'Aurea'; 'Hillieri', which is a very slow growing, rounded bush with blue-green leaves and gets just 6-10 ft (2-3 m) tall; 'Stoneham Gold', which is even smaller and has yellow new foliage that ages to dark green; and the smallest of all, 'Rogersii', which gets less than 3' (1 m) tall. 'Zebrina' is a large cultivar with variegated foliage that is so intense that the whole tree appears to be yellow.
Thuja 'Green Giant' is a noteworthy hybrid between T. plicata and T. standishii, Japanese arborvitae, that has a columnar shape, is reported to grow more than 3 ft (1 m) per year and useful for a quick evergreen hedge/screen.
The natural range of Thuja plicata, western redcedar, is along the Pacific Coast from southeastern Alaska to northern California, and a disjunct, inland area from southwestern Alberta to northern Idaho and northwestern Montana. The species is usually a dominant or co-dominant tree in coniferous forests with douglas-fir (Pseudotsuga menziesii), Sitka spruce (Picea sitchensis) and western hemlock (Tsuga heterophylla).
CultureWestern redcedar is tolerant of a wide variety of soils, alkaline and acidic, dry and moist. Light: These fast growing trees really do best in full sun, but can tolerate shade. The sunnier the position, the denser the foliage becomes. In nature, western redcedars are often obliged to grow in the shade of their taller neighbors until they become tall enough to make their own rules. Moisture: Redcedars like a moist, but well drained soil. They can tolerate dry ground, but thrive in moist soils. Hardiness: USDA Zones 5 - 9. Propagation: The species can be propagated from seed, but the cultivars are started from cuttings.
A western redcedar or two, along with a couple sequoias and maybe a few redwoods, would make a nice statement in a yard the size of, say, a small state. Otherwise, you may want to consider one or more of the smaller selections for use as specimen trees. On the other hand, the species and many of the larger cultivars are used extensively for privacy screening. They grow fast, respond well to clipping, are not eaten by deer, and are tolerant of shade. As a specimen tree in a large yard, western redcedar has few peers, but be advised that the lower branches eventually will reach out and extend way beyond the trunk, and if these are cut off, the tree loses a lot of its character. Gardeners may want to plan ahead: Western redcedar is known to live more than 1400 years.
The smallest cultivars are excellent in rock gardens. Thuja 'Green Giant', the hybrid, is excellent for privacy screening, parking lot and highway median plantings, and windbreaks.
Western redcedar is an important timber tree in its natural range. The soft, reddish wood has a pleasant aroma, is easy to work, and resists rot. It is widely used for outdoor applications such as fence posts, shingles, siding and lawn furniture. Closets and chests lined with redcedar repel moths and other destructive insects. Native Americans stripped the bark from western redcedars for use in making rope, mats, baskets and clothing.
There are only six species in the genus Thuja, with four occurring in eastern Asia. The other North American species is Thuja occidentalis, American white cedar, which occurs in the east.
Some people apparently are allergic to contact with redcedar foliage.
Steve Christman 8/31/10