Common Name: Western Red Cedar

General Information

Thuja plicata is an evergreen tree with a conical crown; it usually grows up to 50 metres tall, exceptionally to 75 metres, though it can be stunted in harsh environments. The straight, cylindrical bole is up to 200cm in diameter (exceptionally to 500cm), and is often buttressed at the base.
Thuja plicata is an important commercialy harvested timber tree, its soft but extremely durable wood being valued for construction etc. The tree also has a wide range of traditional uses as a food, medicine and source of materials. The plant is cultivated as a timber crop in N. America and Europe, and is also commonly grown as an ornamental in parks and gardens - many cultivars have been developed[].
Despite extensive logging, the extensive range and abundance of Thuja plicata makes it ineligible for any threatened category. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

Known Hazards

The essential oil in this plant contains thujone. Thujone is a GABA receptor antagonist which allows neurons to fire more easily. In larger doses this can cause muscle spasms and convulsions, and can also be toxic to brain, kidney, and liver cells.
There has been a lot of negative press regarding thujone, particularly in the mid 19th century when thujone was reported to be more dangerous than alcohol - since shown to be exaggerated; and reports in the 1970’s that it might have a similar effect on the brain to THC (found in cannabis) – since found to be incorrect.
Thujone is probably best known for its use in the alcoholic drink ‘Absinthe’. It is also found in the essential oils of many other plants that are used in herbal medicines and foods, including Arborvitae (Thuja species), some Junipers (Juniperus species), Wormwoods (especially Artemisia absinthium) and Sage (Salvia officinalis). There are some legal restrictions in various countries on the quantity of thujone that can be added to foods and drinks and these vary between countries.
Side effects from consuming thujone can include sleeplessness and anxiety but, unless the pure essential oil is used, the quantity of thujone found in plants is well within safety levels. Pregnant women, however, may be advised to restrict their use of thujone-containing plants.

Botanical References

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Range

Western N. America - British Columbia to California.

Habitat

Grows singly and in small groves, on various substrates, in moist to swampy soils, usually in shady forests; at elevations from sea-level to 1,500 metres[, , , ].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	40.00 m
Growth Rate	Fast
Pollinators	Wind
Cultivation Status	Wild

Cultivation Details

Thuja plicata is found in two, more or less disjunct areas, each with their own distinct climate - the Pacific coastal mountains and Rocky Mountains. The Pacific coastal mountains experience high rainfall levels (up to 6,600mm per annum with the majority falling in winter) and mild winters. Here, in the wet forests amongst many other giant species such as the Redwood (Sequoia sempervirens), Thuja plicata can be up to 75 metres tall and live for more than 1,000 years. In the Rocky mountains of the interior, the climate is much drier (rainfall does not exceed 1,200mm per annum), winters are much colder, and the tree is usually less than 50 metres tall[].
Prefers a moist loamy soil[, ]. Dislikes dry soils[]. Not suitable for light sandy soils because it is shallow rooting[], but it succeeds on most other soil types, even on waterlogged soils and heavy clays[, ]. Succeeds in chalky soils[]. Prefers some shelter from the wind according to some reports[, ] whilst others say that it is fairly wind resistant[, ]. Trees tolerate salt winds[] but not severe maritime exposure[].
The wood and foliage are highly aromatic[]. The foliage has a strong fruity smell, like pear-drops or crushed apples[].
A fast growing tree, it often puts out new growth of 1 metre a year and can average 60cm a year for the first 40 years. Increase in girth can also be rapid, 5cm a year for the first 60 years has been recorded[].
The tree is sometimes planted for forestry in Britain[], it is at its best in the moister western half of the country[, ].
There are many named varieties selected for their ornamental value[].
Plants are very tolerant of light trimming, so long as this is not back into old wood. Plants can also retain their lower branches unless these are shaded out by neighbouring plants[].
The foliage turns bronze in cold weather[].
Trees are notably susceptible to honey fungus[, ].
Western redcedar ( Thuja plicata ) is the provincial tree of British Columbia[].

Edible Uses

Inner bark - fresh or dried[, , ]. The inner bark can be dried, ground into a powder and then used as a thickening in soups etc or mixed with cereals when making bread.

A pitch obtained from the trunk has been used as a chewing gum[].

Medicinal

Western red cedar was employed medicinally by a number of native North American Indian tribes, who used it to treat a wide range of complaints[]. It is seldom, if ever, used in modern herbalism.

An infusion of the leaves has been used in the treatment of stomach pains and diarrhoea[]. A decoction of the leaves has been used in the treatment of colds[].
A decoction of the powdered leaves has been used externally to treat various internal pains, including rheumatism[].
The leaf buds have been chewed in the treatment of toothaches and sore lungs[]. A decoction of the buds has been used as a gargle[].

A decoction of the small branches has been used in the treatment of coughs, colds and tuberculosis[]. A weak infusion has been drunk in the treatment of painful joints caused by rheumatism or arthritis[].
A poultice of the crushed bough tips and oil has been applied to the back and chest in the treatment of bronchitis, rheumatism, stomach pains and swollen neck[]. An infusion of the twigs has been used as a wash in the treatment of venereal disease sores[].

A decoction of the stem tips and the roots has been used in the treatment of colds[].

An infusion of the bark and twigs has been used in the treatment of kidney complaints[].

An infusion of the seeds and twigs has been used in the treatment of fevers[].

The chewed bark, or a decoction of the bark, has been drunk to induce menstruation[].

A moxa of the inner bark has been used as a counter-irritant for the skin[]. A poultice of the inner bark has been applied to carbuncles[].

The bark has been pounded until it is as soft as cotton and then used to rub the face[]. The very soft bark has been used to bind wounds and cover dressings[].
The shredded bark has been used to cauterize sores and swellings[].

Agroforestry Uses:

When grown in an open position, this tree will usually retain its lower branche in full leaf - since it is also tsolerant of light trimming and of reasonable exposure, it can be grown as a hedge or as part of a shelterbelt[].
Western redcedar can be planted as a pioneer species for restoring woodland on disturbed sites within its natural range. It may be the species of choice for reforesting high, brush-risk areas near the coast It is suitable for planting on slightly dry to wet nutrient-poor to nutrient-rich sites (usually in compination with other suitable conifers). It does best when planted in mineral soils on upland sites and in well-decomposed organic material on lowland sites. Containerized rees appear to perform somewhat better than bareroot stock. Direct seeding is practical and effective where a mineral soil seedbed is available[].

Other Uses

An infusion of the boughs can be used as a hair wash to treat dandruff and scalp germs[].

The fibrous inner bark can be pounded until it is soft and then used as a sponge for scouring dishes etc, or can be used for making rough clothing, blankets, mats, ropes, sanitary towels, a padding in a baby's cradle, nappies etc. Waterproof hats, capes, trousers, skirts etc can be made from the inner bark[]. It is also used in thatching and as a stuffing material for mattresses[, , , , , , , ]. Inner bark strips have been used as a roofing material[]. The bark has also been used to make paint brushes[].

The inner bark has been used to make a wick for oil lamps[].

The inner bark has been used for making baskets[].
The roots are used in basket making, making nets etc[]. The roots have been used in coiled and imbricated baskets[]. The roots have been peeled, split and used to make coiled watertight baskets that can be used for boiling water[]. The roots are harvested in the spring or early autumn when it is easier to remove the bark. The outer strips of the roots are used to make the bottom of the basket, the centre core is used in the coils and the root bark, because of its toughness, is used to make the edges[].

The fibrous bark is used for roofing and the sides of shelters. It is also used as an insulation[, ].
A fibre obtained from the bark is used in making paper. The fibre is about 3.8mm long (this refers to the heartwood fibre, the inner bark fibre is probably longer)[]. Branches can be harvested at any time of the year, they are cut into usable pieces and pre-soaked in clear water prior to cooking. They are then cooked for six hours or more with lye. It is difficult to rinse it to clear water because it seems to be a dye material[]. The fibre is then hand pounded with mallets, or put through a blender or a ball mill for six hours. It is difficult to hydrate properly. The resulting paper is a rich deep brown/red[].

The slender pliable branches are used as a high quality rope[]. They are gathered in spring, peeled and, if thick, are split into halves or quarters. They are then twisted and worked until soft and pliable and finally woven together to make the rope[].

A green dye can be obtained from the leaves and twigs[].

The inner bark can be used as a tinder[].

The wood is aromatic, light, soft, straight-grained, not strong, very resistant to decay. This resistance to decay is probably due to the existence of powerful naturel fungicides in the wood[]. The wood from fallen trees remains sound for at least 100 years[]. It is pale to dark red in colour[]. The wood was widely utilized by many native North American peoples, who used it for making a wide range of items including canoes, houses, totem poles, bowls, spoons, ladles and tools[, ]. It is currently used in making greenhouses[, , , ]. The wood is not of such good quality when grown in mild humid areas[].
The wood makes a good fuel, burning with very little smoke, though it burns quickly[].
The wood of this species provided the main building material for the Amerindian tribes along the Pacific coast, who developed a technique to split large planks from the lower boles of big trees without destroying the trees themselves. Nowadays, its main use is for making shingles used in roofing residential buildings; as in most Cupressaceae, the wood is decay-resistant and easy to work. For large construction purposes it is less suitable as it tends to split, but it can be used for a variety of smaller utilities from garden sheds, glass houses, and furniture to tools[].

Propagation

Seed - best sown when ripe in the autumn in a cold frame[]. Stored seed germinates best if given a short cold stratification[]. It can be sown in a cold frame in late winter. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts.
If growing large quantities of plants, the seed can be sown in an outdoor seed bed in mid spring[]. Grow the plants on for two years and then plant them out into their permanent positions in late autumn or early spring.
Cuttings of half-ripe wood, 5 - 8cm with a heel, mid summer in a shaded frame. Forms roots by the end of September but it should be overwintered in a frame[].
Cuttings of almost ripe wood, 5 - 10cm with a heel, September in a cold frame. Forms roots in the following summer. Plant out in autumn or spring[].