Thuja occidentalis as described in 1753 by Carolus Linnaeus (1707–1778), in Species Plantarum 2, is commonly known as arborvitae, a name which is particularly used in the horticultural trade in the United States. It is Latin for "tree of life" - due to the supposed medicinal properties of the sap, bark and twigs. Despite its common names, it does not belong to the cedar genus, nor is it related to the Australian white cedar, Melia azedarach. It is an evergreen coniferous tree, in the cypress family Cupressaceae,
Description. Eastern arborvitae is an evergreen coniferous species of tree with fan-like branches and scaly leaves. Unlike the closely related species Thuja plicata, it is only a small tree, growing to a height of 30 to 60 feet (10 – 20 m) tall with a trunk up to 1.3 feet (0.4 m) in diameter at breast height, exceptionally to 100 feet (30 m) tall with a 5 foot (1.6 m) trunk diameter. The tree is often stunted or prostrate.
Bark is red-brown, furrowed and peels in narrow, longitudinal strips.
Foliage forms in flat sprays with scale-like leaves 0.12 to 0.2 inches (3 – 5 mm) long.
Seed cones are slender, yellow-green at first, ripening brown, 0.4 to 0.6 inches (10 – 15 mm) long and 0.16 to 0.20 inches (4 – 5 mm) broad, with 6 to 8 overlapping scales. The branches may take root if the tree falls.
Distribution. This species is native to Canada — Manitoba, Ontario, Québec; Prince Edward Island, New Brunswick and Nova Scotia. In the USA — Minnesota, Michigan, Wisconsin, Illinois, Indiana, Ohio, Kentucky, Tennessee, North Carolina, Virginia, West Virginia, Maryland, Pennsylvania, New York, Connecticut, Massachusetts, Vermont, New Hampshire, Maine; growing at elevations up to 2,800 feet (0 - 900 m) above sea level on mostly calcareous substrates, neutral to basic swamps, shores of lakes and rivers, uplands, cliffs, and talus.
T. occidentalis is widely used as an ornamental tree, particularly for screens and hedges, in gardens, parks and cemeteries. Over 300 cultivars exist, showing great variation in colour, shape and size, with some of the more common ones being: 'DeGroot's Spire', 'Ellwangeriana', 'Hetz Wintergreen', 'Lutea', 'Rheingold', 'Smaragd' (a.k.a. 'Emerald Green'), 'Techny', and 'Wareana'. It was introduced into Europe as early as 1540.
Thuja occidentalis Photo by Lyle Littlefield garden
Arborvitae in the Powsin Botanical Garden, Warsaw, Poland.
Photo by Albert Jankowski
There is a Thuja occidentalis 'Pulcherrima' ( golden American arborvitae) at the New York Botanical Garden. I do not see it on the cultivar drop-down list. Do you know anything about this cultivar? Thank you.
Does plant spacing determine height? What if I want a denser hedge earlier and plant them 4 feet apart will they still grow very tall? Also, is it OK to prune the north side so I can plant them closer to a walkway, say 2 feet from it and keep them trimmed so they don't block the walkway? The intended use case is for a sun barrier on the south (front) of my house to keep my house cooler in the summer. Ideally they would grow to 40-50 feet and be able to block most of the summer sun.