Common Name: Juniper

General Information

Juniperus communis is a very variable, evergreen shrub or a tree with an erect stem; it can grow up to 12 metres tall, though it is more commonly within the range 1 - 3 metres. The branches can be erect or spreading, so crown shape is very variable[].
The plant has a long history of traditional uses as a food flavouring, medicine and source of materials, and is still often used as a flavouring (especially in gin) and medicine. It is a commonly used medicinal herb in India, where it is gathered in large quantities from the wild for local use and for trade[]. The plant is also commonly grown as an ornamental - a wide range of cultivated forms have been developed some of them suitable for use as hedges or ground cover.
This is the most widespread species of conifer in the world. While it is struggling to survive in some areas, e.g. England, it is increasing elsewhere; both phenomena in its population dynamics are related to shifts in agricultural practices and general land use. Globally, this species or any of its varieties are not threatened with extinction. 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.
Juniper should not be used internally in any quantities by pregnant women[, ].

Botanical References

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Range

Widespread through the Northern temperate zone, south to the mountains of N. Africa, the Himalayas, Korea and southern N. America

Habitat

Pine woods, moorland, calcareous river banks; more rarely mossy, bogs, among undergrowth of deciduous and mixed woods, dry hills, and dry mountain slopes[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Shrub
Height	9.00 m
Growth Rate	Slow
Pollinators	Wind
Self-fertile	No
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Juniperus communis is a very cold-hardy plant, able to tolerate temperatures down to around -40°c when fully dormant. However, although the fully dormant plant is very cold-tolerant, the young growth in spring can be damaged by late frosts.
An easily grown plant, it succeeds in hot dry soils and in poor soils. This species seems very indifferent to soil type and occurs in dry sand, chalk downs, and loose (dolomitic) scree, as well as in acidic peat, with low or fluctuating ground water levels[]. Succeeds in most soils so long as they are well drained[], preferring a neutral or slightly alkaline soil. Does well in chalky soils[]. Grows well in heavy clay soils. Tolerates a pH range from 4 to 8[]. Succeeds in light woodland but dislikes heavy shade[]. Established plants are very tolerant of drought[].
All parts of the plant are very aromatic[].
Juniper is a very polymorphic species that has a long history of culinary and medicinal use[]. It is frequently grown in the ornamental and herb garden, there is a huge range of cultivars of widely diverse habits[, ]. At least some forms tolerate maritime exposure[], there is a thriving colony in an exposed position at Land's End in Cornwall[].
The fruits take 2 - 3 years to ripen on the plant[].
Plants are usually very slow growing, often only a few centimetres a year[].
Resists honey fungus[]. Plants are sometimes attacked by a rust, this fungus has an aecidial stage on hawthorn (Crataegus spp.)[].
A dioecious species - both male and female forms must be grown if fruit and seed are required.

Edible Uses

Some caution is advised when using this plant for food - see the notes above on toxicity.

Fruit - raw or cooked[, , , ]. It is usually harvested in the autumn when fully ripe and then dried for later use[]. A soft, mealy, sweet, resinous flesh[]. The fruit is often used as a flavouring in sauerkraut, stuffings, vegetable pates etc, and is an essential ingredient of gin[]. The aromatic fruit is used as a pepper substitute according to one report[]. The bluish black, globose to ovoid seed cones mature in two years. They are of two distinct sizes, ranging from 6 - 13mm in diameter and containing 2 - 3 seeds[].

An essential oil is sometimes distilled from the fruit to be used as a flavouring[]. Average yields are around 1%[].

The roasted seed is a coffee substitute[].

A tea is made by boiling the leaves and stems[].
A tea made from the berries has a spicy gin-like flavour[].

Medicinal

Juniper fruits are commonly used in herbal medicine, as a household remedy, and also in some commercial preparations. They are especially useful in the treatment of digestive disorders plus kidney and bladder problems[].
The fully ripe fruits are strongly antiseptic, aromatic, carminative, diaphoretic, strongly diuretic, rubefacient, stomachic and tonic[, , , , , , , ]. They are used in the treatment of cystitis, digestive problems, chronic arthritis, gout and rheumatic conditions[]. They can be eaten raw or used in a tea[], but some caution is advised since large doses can irritate the urinary passage[].
When made into an ointment, the fruits are applied to exposed wounds and prevent irritation by flies[].
The fruits should not be used internally by pregnant women since this can cause an abortion[]. The fruits also increase menstrual bleeding so should not be used by women with heavy periods[].

Externally, the plant is applied as a diluted essential oil, having a slightly warming effect upon the skin and is thought to promote the removal of waste products from underlying tissues[]. It is, therefore, helpful when applied to arthritic joints etc[].

The essential oil is used in aromatherapy. Its keyword is 'Toxin elimination'[].

The berries are used in homoeopathy to treat conditions such as catarrhal inflammation of the kidneys; dropsy, with suppression of urine; old persons, with poor digestion and scanty secretion of urine; chronic pyelitis[].

Agroforestry Uses:

Many forms of this species are good ground cover plants for sunny situations[]. Forms to try include 'Depressa Aurea', 'Dumosa', 'Effusa', and 'Repanda'[]. 'Prostrata' can also be used[].
Some forms can make useful low hedges[].
This is largely a pioneer woodland species, occupying natural rock outcrops and other places with skeletal soil and abundant sunlight in woodland and light forest, both broad-leaf and coniferous forest (especially Pinus sylvestris-Betula spp.-Quercus spp.), in which it can obtain local dominance after disturbances (non-fire). It is also prevalent in the ecotone between open woodland and grassland on poor sandy soils and on stabilised inland sand dunes[]. Although slow-growing, it can be used as a pioneer for restoring and establishing native woodland in more difficult terrains and also for establishing woodland gardens[].
Because it is slow-growing, the plant has low value for short-term rehabilitation projects but moderate to high value for long-term projects. It is useful in preventing soil erosion and has potential for restoration in the Canadian arctic and subarctic[].

Other Uses

A decoction of the branches is used as an anti-dandruff shampoo[].
Various extracts of the plant are used as ingredients in commercial cosmetic preparations for skin conditioning, antioxidants, perfumery etc[].

A yellow dye is obtained from the unripe fruit[].

The essential oil distilled from the fruits is used in perfumes with spicy fragrances[].

In hot countries the tree yields the resin 'Sandarac' from incisions in the trunk[, ]. This is used in the production of a white varnish[].

The stems were at one time used as a strewing herb to sweeten the smell of rooms[, ]. The whole plant can be burnt as an incense and fumigant[, , ]. It was used during epidemics in the belief that it would purify the air and cleanse it of infection[].
Fresh or dried juniper branches also make a good insect repellent[, ].

The bark is used as cordage[] and as a tinder[].

The heartwood is reddish-yellow; the sapwood whitish. It is very close-grained, strong, hard, fragrant, very durable in contact with the soil. It is often too small to be of much use, though it is valued for lathework and sculpture, whilst it can also be used as fencing stakes[, , , , ].
The wood makes an excellent fuel[]. It is used to make charcoal that is suitable for gunpowder[].

Propagation

The seed requires a period of cold stratification. The seed has a hard seedcoat and can be very slow to germinate, requiring a cold period followed by a warm period and then another cold spell, each of 2 - 3 months duration[, ]. Soaking the seed for 3 - 6 seconds in boiling water may speed up the germination process[]. The seed is best sown as soon as it is ripe in a cold frame. Some might germinate in the following spring, though most will take another year. Another possibility is to harvest the seed 'green' (when the embryo has fully formed but before the seedcoat has hardened). The seedlings can be potted up into individual pots when they are large enough to handle. Grow on in pots until large enough, then plant out in early summer. When stored dry, the seed can remain viable for several years[].
Cuttings of mature wood, 5 - 10cm with a heel, September/early autumn in a cold frame. Plant out in the following autumn[, ].
Layering in September/early autumn. Takes 12 months[].