Thuja plicata, western red cedar
Coniferous Trees

Thuja plicata

western red cedar

Cupressaceae

Alaska south through BC, Washington, Oregon, northern California, and northern Rocky Mountains; moist to wet forest lowlands and valley bottoms

At a Glance

TypeTree
HabitUpright
FoliageEvergreen
Height100-200 feet (30-60 m)
Width20-60 feet (6-18 m)
Maturity50 years

Growing Zones

USDA Hardiness Zones

5 - 9
Zone 5
Zone 6
Zone 7
Zone 8
Zone 9
These zones indicate the coldest temperatures this plant can typically survive.
Frost Tolerancehardy

Key Features

Deer Resistant
Fragrant (moderate)
Native to North America
Maintenancevery low

Overview

A very large, long-lived, evergreen coniferous tree in the family Cupressaceae, native to moist to wet forest lowlands and valley bottoms from Alaska south through British Columbia, Washington, Oregon, and into northern California and the northern Rocky Mountains — one of the most ecologically and culturally significant trees of the Pacific Northwest. The specific epithet plicata means 'folded,' referring to the overlapping, scale-like foliage. Despite the common name, western red cedar is not a true cedar (Cedrus) but a member of the cypress family. Mature trees grow 100–200 feet (30–60 m) tall with massive, strongly fluted and buttressed trunks 4–12 feet (1.2–3.7 m) in diameter. The foliage consists of small, overlapping, scale-like leaves in flattened, pendulous, fernlike sprays that are bright glossy green above and display distinctive BUTTERFLY-SHAPED white stomatal markings on the underside. The foliage is strongly aromatic when crushed. Small, egg-shaped, upright cones 0.4–0.6 inch (10–15 mm) ripen in late summer. Western red cedar was the most important single plant to Pacific Northwest Coast Indigenous peoples — used for canoes, longhouses, totem poles, bentwood boxes, clothing, and ceremonial objects for thousands of years. Non-toxic.

Native Range

Native to moist to wet forest lowlands and valley bottoms from Alaska south through British Columbia, Washington, Oregon, northern California, and the northern Rocky Mountains.

Suggested Uses

Planted as a large native evergreen conifer for screening, windbreaks, and forest restoration in Pacific Northwest large-scale native landscapes and riparian plantings. Important nesting, roosting, and foraging habitat for numerous birds and mammals. Of exceptional educational and cultural significance — the single most important tree to Pacific Northwest Coast Indigenous peoples for thousands of years; provides essential context for teaching about indigenous uses of native plants, Northwest Coast art, and cultural ecology. Fragrant foliage, dramatic buttressed base, and pendulous fernlike sprays provide year-round ornamental interest in large settings.

How to Identify

Identified as a very large evergreen conifer with flattened, pendulous, fernlike foliage sprays of small overlapping scale-like leaves. Plicata = 'folded.' PRIMARY FIELD CHARACTER: the underside of the foliage spray shows distinctive BUTTERFLY-SHAPED or X-SHAPED white stomatal markings — hold a spray up and examine the underside; the white pattern is immediately visible and diagnostic. Foliage is STRONGLY AROMATIC when crushed — cedar fragrance. Thin, fibrous, REDDISH-BROWN BARK peeling in long vertical strips; strongly fluted and buttressed trunk base in mature specimens. Small egg-shaped upright cones 0.4–0.6 inch (10–15 mm). Not a true cedar (not Cedrus) — a cypress family member.

Appearance

Size & Dimensions

Height100' - 200'
Width/Spread20' - 60'

Reaches mature size in approximately 50 years

Colors

Flower Colors

brown

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~3 weeks
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Spring
Pollen released from small male strobili at branch tips in early spring (March–April). Small, egg-shaped, upright female cones 0.4–0.6 inch (10–15 mm) with 8–12 thin scales mature in late summer (August–September) of the same year, releasing tiny winged seeds. Wind-pollinated. Mature cones persist on branches through fall and winter.

Detailed Descriptions

Flower Description

small egg-shaped upright cones 0.4–0.6 inch; ripen Aug–Sept; wind-pollinated; NOT a true cedar (not Cedrus) — Cupressaceae; most culturally significant PNW tree — canoes/longhouses/totem poles/baskets for Coast Indigenous peoples; extremely rot-resistant heartwood; DATA CORRECTIONS: species null; rewrote curly-brace prose

Foliage Description

bright glossy green above; BUTTERFLY/X-SHAPED WHITE STOMATAL MARKINGS on underside of foliage sprays — primary field character; scale-like overlapping leaves in flattened pendulous fernlike sprays; STRONGLY AROMATIC when crushed; fibrous reddish-brown bark in long vertical strips; strongly fluted/buttressed trunk base; plicata = 'folded'

Growing Conditions

Sun Requirements

Full Sun
Partial Shade
Requires 3-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.0 - 7.0(Neutral)
357912
Soil Types
loamclaysilt
Drainage
moist

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

20-50 years

Care & Maintenance

Care Guide

Plant in full sun to partial shade in moist to wet, acidic soil with a pH of 5.0–7.0. Requires consistently moist to wet conditions — one of the most moisture-demanding native PNW conifers. Very fast-growing in optimal moist conditions. Will grow in average garden soil but performance is best in moist settings. Not appropriate for small gardens given ultimate size. Allow ample space — 30+ feet from structures. The heartwood is naturally rot-resistant and requires no preservative treatment.

Pruning

No pruning required for natural form. Lower branches can be removed to raise the crown as the tree matures. Do not top — severely damages form and structure. Hedging is possible when young but not recommended for natural specimens.

Pruning Schedule

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late spring

Maintenance Level

very low

⚠️ Toxicity Warning

Non-toxic