Western red cedar

Botanical data

Family

Cupressaceae (Cupressaceae)

Height

3–20 m

Width

2–5 m

Habit

Conical

Growth rate

Fast

Position

Full sun, Partial shade

Soil

Humus-rich, Loamy

pH reaction

pH 5.5–7.5

Moisture

Moderate, Moist

Bloom

—

Hardiness

USDA 5b–8a

Propagation

From cuttings, From seed

Characteristics

An evergreen conifer with a regular, conical habit and flattened, scale-like sprays arranged in one plane. It differs from white cedar in several features: a darker and distinctly glossy green, a sweet, fruity scent when crushed (rather than sharp and resinous) and white, butterfly-shaped waxy markings on the underside of the scales; it also lacks the raised resin gland clearly visible in white cedar. It grows fast, adding from a dozen to several dozen centimetres a year, and under garden conditions usually reaches 10–20 m, while as a specimen tree in a mild, moist climate much more — in the wild it ranks among the tallest trees in the world. The plant is monoecious: in spring small, brown male cones and inconspicuous female cones appear on the same plant, and by autumn the latter develop into upright, narrow cones about 1–1.5 cm long, ripening from green to brown. In winter it discolours less than white cedar — the green stays dark, with at most individual sprays turning brown. The root system is shallow, but the species tolerates shade and periodically moist soil better than white cedar and is markedly less prone to dieback in poorly ventilated, overly dense hedges. The price for these advantages is lower frost-hardiness — reaching about zone 5b–6, whereas white cedar withstands down to zone 3a.

Popular cultivars

‘Atrovirens’

The most commonly planted hedging cultivar of this species (and not of white cedar): dark green, glossy, dense foliage that holds its colour in winter, and fast, even growth. The basic material for tall, dense hedges.

‘Martin’

A cultivar selected for hedging, with a compact, conical habit and dark green, prized for slightly better frost-hardiness and even growth. A frequent choice where the typical species can be too sensitive to frost.

‘Excelsa’

A vigorous, tall cultivar with a looser habit, intended for tall screens and hedges. It builds height faster than other forms, so it needs space and regular formative pruning.

‘Zebrina’

A cultivar with foliage banded crosswise in yellow and cream (hence the name), growing slower than purely green forms. Planted as a colourful specimen, not for hedging; it colours best in full sun and turns green in shade.

‘Whipcord’

A dwarf cultivar with long, hanging, cord-like shoots and a soft, dome-shaped habit up to about 1 m. For beds, rock gardens and containers, not for hedging; its unusual habit makes it an ornamental accent.

Growing and care

Companion plants

The evidence level indicates whether the relationship is backed by research, observation, or gardening tradition.

Diseases and pests

Toxicity

History and origin

Western red cedar comes from the moist, oceanic forests of the west coast of North America — from southern Alaska to northern California and inland into the Rocky Mountains. For the indigenous peoples of the Pacific coast it was a tree of first-rate importance: its soft, durable, rot-resistant wood was used to build totem poles, longhouses and dugout canoes, while ropes, mats and clothing were woven from its fibrous bark — hence the English name "western red cedar" and the epithet "canoe tree." The species was scientifically described by the Scottish botanist David Don in 1824. Its seeds were brought to Europe in 1853 by the collector William Lobb, working for the Veitch nursery; the tree was quickly appreciated in the moist British climate, where to this day it ranks among the fastest-growing park conifers. In twentieth-century horticulture the cultivars of western red cedar — especially Atrovirens — became widespread as material for tall, quickly closing hedges, promoted as a healthier and less dieback-prone replacement for white cedar.

Uses

Planted primarily for tall, formal hedges and screens and as a fast-growing specimen and park tree. It is often recommended as a replacement for white cedar where a dense wall of greenery is wanted quickly and greater health matters — plicata grows markedly faster, tolerates shade and harder pruning better and dies back less often in dense plantings. For a hedge it is planted every 60–100 cm, setting the root ball level with the ground; planting too densely and too deeply are among the common causes of browning. A formal hedge is maintained by trimming the current year's growth in spring and late summer. Unlike white cedar, western red cedar regenerates well after harder pruning, which makes it easier to rejuvenate neglected hedges. It requires fertile, deep, well-drained and constantly moderately moist soil; it tolerates prolonged drought and salinity poorly, which is why it browns on the roadward side along salted roads. It grows best in a mild, moist climate — in areas with harsh, snowless winters young specimens are sometimes damaged by winter desiccation and need a sheltered position. The base of a dense hedge creates a dry shade in which only a few ground-cover perennials will cope.

Trivia

• In the wild it ranks among the tallest and mightiest trees in the world — wild specimens exceed 60 m in height and the oldest are over a thousand years old; in hedge and garden cultivation, however, it lives considerably shorter.
• The specific epithet plicata means "folded, pleated" and refers to the arrangement of the scales on the flattened sprays.
• Despite the English name "red cedar" it is not a cedar — cedars (Cedrus) belong to the pine family, while western red cedar belongs to the cypress family (Cupressaceae).
• The fruity, pineapple-like scent of a crushed spray is a simple way to tell it apart from white cedar, which smells sharp and resinous.

Frequently asked questions