Thuja Green Giant Growing Information

Updated February 21, 2017

Thuja Green Giant is an evergreen hybrid between Thuja standishi and Thuja plicata. Thuja Green Giant develops a 60-foot height and 20-foot spread. The pyramid-shaped conifer produces dense, scalelike foliage. Thuja Green Giant grows rapidly and makes an ideal privacy screen or windbreak when planted in mass. Thuja plants do not suffer from many pests or diseases.

Growing Conditions

Thuja Green Giant is hardy in U.S. Department of Agriculture Zones 5 to 7. Thuja prefers moist, well-drained, loamy soil in full sun. The plant adapts to clay, compacted, dry and rocky soils and partial shade. It tolerates drought, heat, humidity and pollution well.

Time Frame

You can plant Thuja Green Giant in spring or fall. An evergreen enters dormancy and handles transplant stress better in fall. Planting too late in the season does not provide the plant enough time to establish. The plant becomes susceptible to winter injury because the foliage loses more moisture than the roots can replace. Set the plant in the ground at least six weeks before the first fall frost. Avoid planting the tree during periods of drought. Place the potted tree in a shaded area until the weather becomes more favourable for planting.


Plant Thuja Green Giant in a hole that is twice as wide and slightly deeper than its container. Turn the plant on it side, and slide it out of the container with the roots attached. Separate the roots, then place the plant in the hole. Replace the soil up to the point where the trunk meets the roots. Tamp the soil to ensure good root-to-soil contact and eliminate air pockets. Water the plant immediately with a soaker hose. Provide Thuja with 1 inch of water per week the first two seasons.


Water newly planted Thuja weekly during the first year. Thuja benefits from a 2- to 4-inch layer of bark or wood chip mulch around the base of the plant to retain moisture and suppress weed growth. Apply 0.151kg. nitrogen fertiliser per foot of height or spread, whichever is greater. A 6-foot tree needs 0.907kg. of fertiliser; a tree with a 3-foot spread requires 0.454kg., according to the University of Wisconsin Extension. Prune in spring or midsummer. Shear the sides of the plant to maintain the desired size. Top or reshape overgrown Thuja over a period of years.


Thuja Green Giant tends to split apart under the weight of heavy snow and ice. Tie the stems of the upper canopy together to support the shrub. To avoid constricting and killing the branches, use cloth strips or old hosiery as opposed to twine or clothesline. Do not tie the branches in tight, circular knots. Loop the cloth around each branch and anchor them to other branches, or tie them to a ground stake.

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About the Author

Renee Vians has been writing online since 2008. She earned a Bachelor of Arts in English and journalism and language arts certification from the University of Nebraska-Kearney. Her articles have appeared on various websites.