Western Red Cedar Plant Care

Western Red Cedar (Thuja plicata) belongs to the Cupressaceae family within the Thuja genus. Western Red Cedar is native to the Pacific Northwest of North America. Western Red Cedar is also known as Giant Arborvitae, Red Cedar, Western Redcedar.

Western Red Cedar displays a pyramidal, columnar growth habit, reaching up to 40 ft tall with a spread of approximately 15 ft. Western Red Cedar produces small cones, not showy.

Leaf size: approximately 0.5 inches.

Water a young or newly planted Western Red Cedar every 7–14 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established trees mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Western Red Cedar thrives in full sun to part shade.

Thuja plicata tolerates temperatures of 0–100°F. Western Red Cedar prefers humidity levels of 30–70%.

Well-draining loamy soil with good aeration. Good drainage is essential for Western Red Cedar to prevent waterlogging, which leads to root rot and fungal issues.

Feed Western Red Cedar every 8 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established trees in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

The PlantoScan app can remind you when to water and when to fertilize each plant.

Choose a spot with full sun to part shade and well-draining loamy soil with good aeration. Avoid low spots where water collects after rain.

Plant container-grown or balled-and-burlapped trees in spring or early autumn, setting the root flare at soil level, and water well after planting.

Western Red Cedar can spread to about 15 ft (4.6 m) and reach about 40 ft (12 m) tall. Space plants about 15 ft (4.6 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the tree spacing calculator.

Prune Western Red Cedar while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the tree in one year.

Water deeply in late autumn before the ground freezes — evergreens keep losing water through their needles all winter, and spread a 5–8 cm (2–3 in) layer of mulch over the root zone, keeping it away from the trunk.

Young and container-grown trees need extra protection: roots in a pot freeze much more easily than roots in the ground.

Western Red Cedar can be propagated through seeds, cuttings. Similar propagation techniques also apply to arborvitae plant care, which shares the same genus.

See all plants toxic to cats and plants toxic to dogs.

Western Red Cedar is susceptible to spider mites, bagworms, scale insects. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.

Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.