Thuja 'Green Giant'

Once misnamed, Thuja 'Green Giant' now has an identity of its own, and may become an outstanding alternative screening evergreen to Leyland cypress.

This newly renamed conifer rises to 60 feet or more in height and has a tightly pyramidal growth habit. It is very versatile and can be used as a specimen or as a background plant to other plantings. It tolerates a wide range of soil types, from sandy loams to heavy clays, and thrives in a wide variety of climatic conditions. 'Green Giant' has a naturally uniform growth habit and exceptional winter color. It also roots readily from cuttings taken at any time of the year.

Through a series of mix-ups, this Thuja standishii x T. plicata putative hybrid was until recently awkwardly confused with T. occidentalis 'Giganteoides.' Thanks to the assistance of Robert Marquard, director of research at the Holden Arboretum in Mentor, Ohio, a series of protein analyses were performed that determined its identity. Nurseryman Don Shadow then suggested its present name to avoid confusion and honor its distinction.

'Green Giant' has scalelike foliage in flattened sprays, coarse in texture, glossy green above and paler beneath. Branches are somewhat thickened, horizontal to ascending with dense, alternate branchlets. Cones are oblong, 0.4-0.6 inches (1-1.5 centimeters) in length, with a spine at the tip of the scale. They are borne upright on the stem and persist through the winter months. Green at first, the cones turn brown at maturity. As the tree ages, its bark becomes thick and fibrous.

'Green Giant' has no serious pests or disease problems, grows rapidly, has a rich green color and outstanding winter color, and nurseries who tested it found it as a good substitute to Leyland cypress. A large specimen at the U.S. National Arboretum, taken from the original plant sent from Denmark in 1967 by D.T. Poulsen, is an outstanding evergreen about 30 feet tall. We believe its new and correct name reflects the beauty, utility and giant appeal of this exceptional conifer.

- Susan F. Martin, curator of conifers, U.S. National Arboretum, Washington, D.C., and Kim Tripp, director of The Botanic Garden of Smith College

Specifics

Name: Thuja 'Green Giant'

Family: Cupressaceae.

Hardiness: USDA Hardiness Zone 5.

Description: Evergreen conifer to 60 feet tall, with glossy, green foliage and dense, alternate branchlets. It has a naturally uniform growth habit and outstanding winter color.

Landscape value: Rich color and uniform growth habit suggest it as an evergreen screen or a specimen plant for a large landscape, park or botanical garden.