Thuja occidentalis / eastern arborvitae

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,

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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.
natural range of <em>Thuja occidentalis </em>
natural range of Thuja occidentalis

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.

Attribution from: Wikipedia

Thuja occidentalis
Photo by Lyle Littlefield garden
Arborvitae in the Powsin Botanical Garden, Warsaw, Poland.
Photo by Albert Jankowski

Comments

Katherine Wagner-Reiss

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.

Katherine Wagner-Reiss

Thank you, David. I will certainly try to submit a photo of 'Pulcherrima' to ACS after my next visit to the New York Botanical Garden in the Bronx, NY.

Kelly Polello

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.

Patricia V.

My neighbor decimated the trees between our properties and I would like to know which variety of thuja occidentalis would grow 15 to 20 feet but also have a narrow diameter? What kind of spacing would be best? I still want to let all the sun in, but create a natural looking screen that would obliterate their house, which now feels like it is practically in my backyard. I did come across the junior and baby varieties sold by a reputable company online but wonder if there is something else out there.... I live in the northeast US. Thanks!

Maxwell Cohn

'DeGroot's Spire' is probably the narrowest one that you'll be able to easily find. In reality though, most of them are pretty narrow if they've raised with a single leader instead of being topped and sheared every year.

Jan Frazee

Will Thuja occidentalis thrive at 3500 elevation in NC mountains?

Cg

I am currently selecting Thuja for a hedge. What are some notable differences between Thuja occidentalis 'Holmstrup' & 'Smaragd'? Thank you!

Mary Gilbert

I am trying to find a Thuja occidentalis that is the straight species, not a cultivar. They seem not to be available anywhere. Yes, hundreds of cultivars, but not the straight species. Can you help?

Dee Gardener

I've bought seedlings each spring for the last few years from my local county conservation office. They offer a seedling sale every year. Maybe check with yours? They're a government agency outreach kind of organization. Even if they don't offer seedling sales, they may know of wholesalers or retail places you could check. (Funding the conservation district is one of the only decent uses I've seen of taxpayer dollars... but that's another subject for another day.) What's really nice is that if bunnies trim your arborvitae for you like they do mine over the winter trying to keep their teeth sharp and worn down, the trimmings root easily in water (give them 3 or 4 weeks to see roots) which turn to new seedling trees.

Elaine

I was told my arborvitae hedge is a Teemed arborvitae. I live in Mich but I do not see that kind of arborvitae in any article

Bill Barger

I've never heard of that term. Were they referring to the cultivar? Maybe it's something new?