Genus Thuja Species x Cultivar 'Green Giant' Common Name 'Green Giant' Arborvitae Patent ID Height 25 to 30 Feet Spread 18 to 20 Feet Habit Uniformly conical tree. Moderate growth rate. Zone 3 to 8 Culture Full Sun. Flower Flower Color Foliage Dark green, scale-like. Evergreen. Category: Conifer Description Virtually disease free. Responds well to shearing. Excellent substitute for Leyland Cypress.