Northern White-cedar, Arborvitae (Thuja occidentalis) Growing & Care Guide for Gardeners
Article by Dean Ravenscroft, Ph.D. - Updated 1st Feb 2024
- Plant Characteristics: A coniferous evergreen tree with dense, fan-like foliage and a pyramidal shape. Widely used for privacy hedges, screens, and as a standalone specimen in landscapes.
- Growing & Care: Prefers full sun to partial shade and moist, well-drained soil. Tolerates a range of soil types and conditions, including wet soils. Regular watering is beneficial, especially in dry conditions.
- Tips for New Gardeners: Easy to grow and maintain, making it a popular choice for beginners. Prune regularly to shape and control its size. A versatile plant that provides year-round interest and privacy.
The Thuja occidentalis plant is a small to medium sized evergreen coniferous tree. It is commonly known as the Eastern Arborvitae or Northern White-cedar (It is Cedar-like as opposed to being a true Cedar of the Cedrus genus).
It natively grows in Eastern Canada and North-eastern USA.
Thuja occidentalis 'Little Giant' cultivar photograph by F. D. Richards.
Although full grown pure Thuja occidentalis species trees may grow from 20 feet (6 m) up to 50 feet (15 m) in height (depending upon environment), there are numerous dwarf varieties of this conifer available.
This means that it can be used as an ornamental plant even in small gardens. For example the cultivar Thuja occidentalis 'Danica' (white-cedar 'Danica') has a height and spread of around 20 inches (50 cm).
There are over 300 known cultivars of Thuja occidentalis available. These have a large range of shapes (from conical and narrow pyramid shape to round), leaf color (golden to green), and sizes (dwarf to natural tree).
This tree typically has a single trunk with a diameter of around 3 feet (90 cm), though some trees can grow twice as thick in the right circumstances.
The bark is a reddish-brown and is furrowed in trenches. Bark may turn grayish in more mature trees. Bark sheds off in strips.
Natively the Eastern Arborvitae is found in wet forests and swamps, where they are easily able to out compete other tree larger species of trees.
Deer naturally feed on Arborvitae trees in the winter, so don't grow if deer are an issue in your area.
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Quick Growing and Care Guide
- Scientific Name: Thuja occidentalis
- Common Name (s): Eastern Arborvitae, Northern White Cedar, Tree of life, American arborvitae, Grandmother Cedar.
- Growing Zone (USA / UK Hardiness): 2 to 7 / H7
Plant Details
- Life Cycle / Plant Type: Evergreen Conifer
- Plant Height: 20 to 50 feet (6 m to 15 m); Cultivars, can be as small as 20 inches (50 cm); medium sized cultivars for the garden tend to be around 8 to 13 feet (2.5 m) in height.
- Plant Spread: 10 to 15 feet (3 to 4.5 m); dwarf cultivars 4 to 20 inches (10 to 50 cm); medium sized cultivars 5 to 8 feet (1.5 to 2.5 m).
- Blooms: Does not flower
- Leaf Foliages: Depends on cultivar. Native tree has flattened fan shaped sprays. Needled leaves are pointed and scale like. Aromatic. Dull green-yellow colour.
- Cones: Ovoid. green when juvenile; brown when mature. 1/3rd to 1/2 inch (9 to 14 mm) long. 8 seeds per cone.
Growing Conditions
- Best Light Conditions: Full sunlight to partial shade.
- Suitable Soil Types: Well drained gives best results, but species is naturally found in wet forests and swamps.
- Suitable Soil pH: neutral to alkaline.
- Soil Soil Moisture: Medium, Wet
- Sowing, planting, and Propagation: Semi-hardwood cuttings in late summer or at the start of autumn. Spacing depends on cultivar, but at least 2 feet (60 cm) for smaller varieties. See plant spread for a better idea of spacing for Eastern Arborvitae cultivars. If growing from seed then place half a dozen cones into a paper bag and leave in a sunny area to dry out. Shake to remove seeds. Sow onto peat moss and cover with a lid. imbibe in the fridge for about 3 months. place tray into sunny part of the garden in spring. Once seedlings have reached about 2.5 inches (7 cm) transfer to final location (dig a hole larger than the root ball, add a thin layer of potting compost, then plant the root ball and compress with top soil. Provide a good watering.
- Care: Low maintenance. Extremely cold hardy. Protect from high winds when young. Some cultivars may irritate the skin so wear gloves. Protect from conifer aphids (numerous natural enemies or wash with soapy water) and scale insects (can be biologically controlled with parasitoid wasps, Black ladybird, or removing egg masses).
Further Information
- Best used for: Screening, hedging, ornamental, smaller cultivars in containers, Winter interest, air polluted areas, landscaping.
- Miscellaneous: Oldest known tree is about 1050 years old. Genus named after a type of Juniper. Used in traditional medicines by the indigenous people, the Ojibwe. Often used in local construction as lumber, especially for fences and log cabins. Contains essential oils that are used as a tincture, disinfectant, cleanser, and for soap.
- Family: Cupressaceae (Cypress family).
- Cultivars: Thuja occidentalis 'Holmstrup': Slow growing, medium sized, Rich green foliage; 'Amber Glow': Slow growing, compact, golden-yellow foliage; 'Smaragd'; Slow growing; conical; bright green leaves; 'Danica'; dwarf; bright green sprays tinged with bronze in the winter; 'Degroot's Spire'; dense, conical, yellow-green leaves.
- Further Reading and References used for this Thuja occidentalis growing guide: Conifers.org; T. Occidentalis cultivars
I hope that you enjoyed this guide on how to grow Thuja occidentalis plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Cupressus sempervirens and X Cupressocyparis leylandii plants.
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