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Publication #ENH-788

Thuja plicata: Giant Arborvitae1

Edward F. Gilman and Dennis G. Watson2

Introduction

A native western North American tree, Giant-Cedar can reach 180 to 200 feet in height in some areas of the Northwest but is more often seen at 50 to 70 feet in height with a spread of 15 to 25 feet. Forming an upright pyramidal silhouette with strongly horizontal branches, Giant-Cedar is an evergreen with fragrant, dark green, delicate needles which generously clothe the branches, casting dense shade beneath the tree. The insignificant yellow flowers are followed by small, half-inch cones which seem a little out-of-place on such a large tree.

Figure 1. 

Mature Thuja plicata: Giant Arborvitae


[Click thumbnail to enlarge.]

General Information

Scientific name: Thuja plicata
Pronunciation: THOO-yuh ply-KAY-tuh
Common name(s): Giant Arborvitae, Giant-Cedar, Western Redcedar
Family: Cupressaceae
USDA hardiness zones: 6A through 8A (Fig. 2)
Origin: native to North America
Invasive potential: little invasive potential
Uses: hedge; screen; specimen; highway median
Availability: somewhat available, may have to go out of the region to find the tree

Figure 2. 

Range


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Description

Height: 50 to 70 feet
Spread: 15 to 25 feet
Crown uniformity: symmetrical
Crown shape: pyramidal, columnar
Crown density: dense
Growth rate: moderate
Texture: fine

Foliage

Leaf arrangement: unknown (Fig. 3)
Leaf type: simple
Leaf margin: entire
Leaf shape: scale-like, ovate
Leaf venation: none, or difficult to see
Leaf type and persistence: evergreen, fragrant
Leaf blade length: less than 2 inches
Leaf color: green
Fall color: no color change
Fall characteristic: not showy

Flower

Flower color: yellow
Flower characteristics: not showy

Fruit

Fruit shape: cone, elongated
Fruit length: .5 to 1 inch
Fruit covering: dry or hard
Fruit color: brown
Fruit characteristics: does not attract wildlife; not showy; fruit/leaves not a litter problem

Trunk and Branches

Trunk/bark/branches: branches don't droop; very showy; typically one trunk; thorns
Pruning requirement: little required
Breakage: resistant
Current year twig color: green, brown
Current year twig thickness: thin
Wood specific gravity: 0.32

Culture

Light requirement: full sun, partial sun or partial shade, shade tolerant
Soil tolerances: clay; sand; loam; acidic; alkaline; well-drained; occasionally wet
Drought tolerance: moderate
Aerosol salt tolerance: moderate

Other

Roots: not a problem
Winter interest: no
Outstanding tree: yes
Ozone sensitivity: unknown
Verticillium wilt susceptibility: resistant
Pest resistance: resistant to pests/diseases

Figure 3. 

Foliage


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Use and Management

Tolerating shearing quite well, Giant-Cedar is ideal for use as a hedge or screen, or a specimen for a large landscape. The wood of this tree is commercially used in North America for the manufacture of roof shingles, deck boards, and siding and the split trunks were often used by Indians for making totem poles or canoes. Due to its narrow crown, it works well close to buildings where soil is frequently alkaline and drainage is poor.

Giant-Cedar naturally occurs on river banks, swamps, and even bogs so should be grown in full sun or partial shade on moist, well-drained, fertile soil, and prefers a moist atmosphere. Apparently pH adaptable, growth is stunted on dry soils. Provide irrigation during the summer or locate in an area with moist soil.

A few of the many cultivars include: `Atrovirens', excellent shining green foliage; `Canadian Gold', golden foliage; and `Fastigiata' (`Hogan'), dense columnar silhouette, very resistant to bagworms - they do not appear to infest this cultivar as much as the species.

Propagation is by seed or cuttings.

Pests and Diseases

No pests or diseases are of major concern but may be occasionally bothered by bagworm.

Footnotes

1.

This document is ENH-788, one of a series of the Environmental Horticulture, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date November 1993. Revised December 2006. Reviewed May 2011. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Edward F. Gilman, professor, Environmental Horticulture Department; Dennis G. Watson, former associate professor, Agricultural Engineering Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.