Western Red Cedar (Thuja plicata Atrovirens AGM)

Western Red Cedar (Thuja plicata Atrovirens AGM) is native to western North America. This impressive evergreen conifer is a member of the cypress family Cupressaceae.

Happy growing from sea level to 2,290 m above sea level, it has two other growing properties that has made it so popular in gardens and larger landscapes. First, it is exceptionally shade tolerant and can even reproduce under extreme shade. Second, it is riparian, meaning it will tolerate the damp, even boggy, conditions associated with areas where land meets rivers, lakes and other large bodies of water.
Unsurprisingly, Western Red Cedar has been successfully introduced across the world’s temperate zones – western Europe, Australia (at least as far north as Sydney), New Zealand and the eastern United States. It is naturalized in Britain where it is increasingly sought after for planting as a hedge an/or ornamental specimen.

What’s in a name?

Western Red Cedar is one of those plants that has a multitude of names, especially in its native region.

Because Thuja plicata Atrovirens is not a true cedar, North American authorities in particular prefer to spell its anglicised name in two words rather than three: Western Redcedar rather than Western Red Cedar. This side of the pond, the three word name still prevails, unchallenged by the many alternatives used in America and Canada. These include: Giant Arborvitae (tree of life); Giant Redcedar; Pacific Redcedar; Shinglewood; British Columbia Cedar; Canoe Cedar; Red Cedar and its native American name of Long Life Maker.

Its botanical name breaks down as follows:

  • Thuja: From the classical Greek thua, the name of an African tree. In medieval and then in the New Latin of the C.18th, thua became thuia.
  • Plicata: From the Latin plicare, meaning folded in plaits – a reference to the pattern of its small leaves.
  • Atrovirens: Dark green – from the Latin atratus (blackened, dark) and virens (green).
  • AGM: And let’s not forget, Western Red Cedar has the RHS Award of Garden Merit

In Britain, the Western Red Cedar (Thuja plicata Atrovirens AGM) is grown primarily as a highly attractive and eminently practical hedge for both formal and informal gardens.

Like many other hedging plants, the Western Red Cedar is, of course, a tree – a tree that if left to nature and given the space, time and right conditions will grow to 70m and live for well over 1,000 years. It may seem, therefore, somewhat incongruous that it can be grown with no trouble and little maintenance as a classic 2m high, close-knit garden hedge. But then, the same is true for Yew, Hornbeam, Beech etc. – proving that gardening is no more, but no less, than the redirection of nature’s potential. We’ll explore just how this can be achieved in the next post – here we’re concentrating on the aesthetic appeal of Western Red Cedar.

As with any conifer, Western Red Cedar is grown for its evergreen foliage. In botanical terms the foliage forms “flat sprays with scale-like leaves in opposite pairs, with successive pairs at 90 degrees to each other. The foliage sprays are green above and green marked with whitish stomatal bands below. Individual leaves are 1-4 mm long and 1-2 mm broad on most foliage sprays, but up to 12 mm long on strong-growing lead shoots.” The rich green foliage is tactile, delicate and feathery yet grows sufficiently thick to offer privacy, protection and security. It is a perfect foil for the attractive red-brown bark. It also has a wonderfully aromatic scent, subtly reminiscent of pineapple.

With simple trimming you can create simple, classic perfection of a geometric hedge – but if you leave it be (you can still trim the top to maintain the required height) you may also get to enjoy its red/purple pollen cones that then form slender seed-baring cones, maturing from yellow-green to green to brown. The choice is yours.
In the next post, we’ll look at growing Western Red Cedar.

Growing Western Red Cedar is both simple and rewarding and its popularity is deservedly on the increase.

More information about western red cedar

  • Foliage: Flat sprays of small, aromatic, scale-like leaves
  • Cones: Small, slender and knobbly.
  • Scent: Fragrant leaves, reminiscent of pineapple
  • Hardiness: Once established Western Red Cedar will cope with just about anything our climate may throw at it though it’s not really suited to coastal gardens – Griselinia littoralis AGM, Photinia x fraseri ‘Red Robin’, Escallonia macrantha Rubra or Buxus Sempervirens are good alternatives if you garden by the sea.
  • Aspect: Can be planted facing any aspect, exposed or sheltered.
  • Ease of maintenance: Extremely easy.
  • Specialist care: Protect young plants from drying winds.
  • Pruning: No major pruning is required – minor trimming to maintain shape and tidiness can be carried out any time from spring through to early autumn but is best done in August. Unlike with Leylandii, you can cut back into old wood.
  • Drought Resistance: Good
  • Soil pH: Acid, through neutral to alkaline.
  • Soil Type: Chalk, Clay, Sand or Loam
  • Moisture: Prefers damp but well-draining soil.
  • Light: Prefers full sun.
  • Height: 12m+
  • Spread: 8m+
  • Rate of Growth: Fast.
  • Versatility: On the practical front, Western Red Cedar’s thick growth makes it one of the best barrier hedges available as it is effective against wind, noise, prying eyes and intruders. Aesthetically it scores on all fronts as either a statement hedge or specimen.