Western arborvitae (Thuja plicata) is a large native evergreen tree from the Western U.S. (USDA hardiness zones 5-7). As many as 30 cultivars are available among dwarf, weeping, and variegated leaf forms. One of the most popular selections is ‘Green Giant,’ a hybrid between T. plicata and T. standishii, a Japanese arborvitae.

In its native Oregon the species (T. plicata) attains heights greater than 100 feet with a strong vertical presence (see photo). In the Eastern U.S., western arborvitae typically matures to 60 to 70 feet tall and 25 to 35 feet wide.

Established Green Giant arborvitaes grow at a torrid pace, as much as 2 to 3 feet per year. During its initial 2 years growth rate may be slow, as it adapts to the new site. A single row, planted 10-12 feet apart, should provide a dense privacy screen within 10 years. I recommend minimum 16 feet spacing.

Its narrow pyramidal form stands tall under winter ice or snow. The lustrous dark green summer foliage naturally bronzes off in cold winters, and greens back up with spring’s arrival. Green Giant is disease and pest resistant. Deer seem to leave it alone. Young trees exhibit a grayish bark, which ages to fibrous reddish-brown. Small ½-inch long cones mature dark brown in the fall.

Green Giant retains its lower branches longer than most evergreens. Pruning is rarely necessary except to remove multiple leaders or to hedge them for a shorter privacy screen. Over the years, lower branches near the ground may root and form a mini-forest or thicket.

Green Giant prefers a cool, moist, well-drained soil. The soil pH should be mildly acidic to near neutral. It can be planted on a sunny or partially shady site. An established plant handles moderate shade and summer dry periods. It is tolerant of heavy clay or urban disturbed soils where few other needle evergreen trees survive. Roots are deeply anchored and Green Giant is unlikely to be blown over by strong winds.