Thuja 'Green Giant' is a fast-growing evergreen hybrid that reaches 40 to 60 feet tall with a dense, narrow form, thriving in hardiness zones 5 through 8. This cultivar, bred from Thuja plicata and Thuja standishii, has earned a reputation as a disease-free alternative to Leyland cypress, especially throughout the southeastern United States where it handles both heat and humidity with ease. Its columnar shape and year-round deep green foliage make it an outstanding choice for screening and hedgerows, while its moderate water needs and low maintenance demands mean once established, it largely takes care of itself.
Partial Sun
Moderate
5-8
720in H x 216in W
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High
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Green Giant's real strength lies in its hybrid vigor and disease resistance. Reaching 40 to 60 feet with a narrow, dense habit, it delivers the visual impact of a mature screen in far less time than older cultivars. The plant tolerates a surprisingly wide range of soil conditions and even handles some dry spells, making it far more adaptable than the Leyland cypress it was developed to replace. Scale insects and bagworm can occasionally appear, and root rot may develop in poorly drained sites, but these issues remain minor compared to the serious disease susceptibility that plagues less robust varieties.
Green Giant serves primarily as a tall screening plant and hedgerow specimen. Its narrow, columnar form makes it exceptionally useful for creating visual barriers along property lines or screening unsightly views without consuming excessive width. When planted 5 to 6 feet apart, it forms a dense hedge that provides year-round privacy. The plant also works well as a single specimen in landscapes where vertical emphasis is needed, lending architectural structure to foundation plantings and large garden spaces.
No timeline data available yet for this variety.
Plant in spring or fall when soil is workable. Space trees 5 to 6 feet apart for hedgerow screens, or further apart for other landscape uses. Dig a hole no deeper than the root ball and twice as wide, backfilling with existing soil improved with organic matter. Water thoroughly after planting and maintain consistent moisture for the first growing season.
Green Giant naturally develops a dense, narrow columnar form requiring minimal pruning. Remove any dead, diseased, or crossing branches as they appear. Light shearing in early summer maintains form and encourages density, though the plant's naturally compact habit means aggressive pruning is rarely necessary.
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“Green Giant emerged as a deliberate cross between Eastern arborvitae (Thuja plicata) and Japanese arborvitae (Thuja standishii), engineered specifically to combine the disease resistance of one parent with the vigor of the other. The hybrid was developed in response to widespread problems plaguing Leyland cypress in warm, humid climates, particularly across the southeastern United States where that species had fallen victim to devastating fungal diseases. By crossing these two Asian and North American species, breeders created a cultivar that preserves the tall, narrow silhouette gardeners love while eliminating the vulnerability that made Leyland cypress increasingly unreliable.”