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How to Take Care of Thuja Occidentalis

The Thuja occidentalis, also known as the American arborvitae, is a tall, pyramid-shaped evergreen tree that is often used to create hedges or privacy screens. The Thuja can grow up to 30 feet tall and 12 feet wide in most yards and is frost-hardy. These trees grow best in USDA zones 3 through 7, enjoying climates with cold winters and enduring minimum annual temperatures of -35 to -40 degrees Fahrenheit. You should plant your arborvitae trees in full sunlight for best growth.

Plant your Thuja occidentalis trees in well-draining, acidic soil. Amend the soil with gypsum or another amendment for acidifying alkaline soils if needed.

Space your Thuja occidentalis trees about 3 feet apart if you’re creating a hedge or privacy screen. Space them 12 feet apart if you’re growing them as individual trees.

Water your arborvitae trees only during dry spells or droughts. During prolonged dry spells, water the trees deeply to soak the soil down to the root zone.

Feed your Thuja occidentalis trees once in early spring and again in mid-fall with a granular 6-12-12 or 10-10-10 NPK (nitrogen-phosphorous-potassium) fertilizer. Follow the directions on the label for fertilizing evergreen trees and shrubs.

Plant Thuja Occidentalis Smaragd

Locate an area with full or partial sun and well-drained soil. Emerald arborvitae prefers loamy, deep soil but will do just fine in rocky, dry and compacted soils of almost any pH without additional amendments. Dig a hole twice the width of the root ball of the plant, and at a depth about the same height as the root ball. Remove the emerald arborvitae from its container or untie the rope securing the burlap around the trunk. If the roots look matted on the edges of the root ball, untangle them with your fingers. Check the soil every few days, and water when the top layer of soil dries slightly.


Fertilize the American arborvitae trees right after planting them with the 6-12-12 or 10-10-10 NPK feed. You should plant the trees in the fall or early spring.

Watch out for pests infesting your Thuja occidentalis trees, such as leaf miners, spider mites and bag worms. Treat the trees with an approved insecticide according to the application instructions on the label.

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