Family: Cupressaceae
Common Name: Juniper

Mostly found in temperate and subarctic regions of the northern hemisphere, although extending into the tropical mountains of Southeast Asia, eastern Africa and Central America, this genus comprises around 60 species of conifers ranging from very tall trees to prostrate shrubs, all of which are long lived and become woody with age. The cones, com­monly known as 'berries', distinguish junipers from other members of the cypress family. They are blueish black or reddish in colour and the seed-bearing scales are fused together, forming a fleshy structure. The juvenile leaves are needle-like, often developing with maturity into cypress-type leaves: short, scale-like and pressed closely to the branchlets. The unpleas­ant smell emitted by the adult leaves of some species when crushed helps to distinguish this genus frorn Cupressus. Junipers are extremely useful plants: apart from their aesthetic appeal, they are probably the hardiest and most trou­ble-free of all the conifers.

Species

J. bermudiana, Bermuda cedar, zone 9, from the Bermudas, is a large, spreading tree, rarely seen outside botanical gardens. The beau­tiful forests in its native habitat have long been denuded.

J. chinensis, Chinese juniper, zone 4, from China, Japan and Mongolia, is generally a bushy tree up to 20 m (65 ft) tall, with fine, dark green, cypress-like foliage. The hard, brownish seed cones, about 1 cm (½ in) in diameter, have a waxy bloom. Cultivar 'Aurea' is an upright shrub, to 10 m (33 ft) or more, with golden yellow foliage in winter and spring, becoming greener in summer; 'Kaizuka' (Synonym: 'Florulosa') is a slender tree, 5-6 m (16-20 ft) tall, with a narrow trunk, deep green, adult-type, corkscrew-like foliage, and strongly ascending, sharply pointed, lateral branches; 'Keteleeri', has a narrow, pyramidal habit, grow­ing to 10 m (33 ft) high, with adult-type, dark green foliage and masses of cones; 'Stricta' has a slender, columnar habit, with blueish, less prickly foliage, especially when young, and some adult-type foliage.

J. communis, common juniper, zone 3, from northern Europe, Asia and North America, may be a slim, upright tree up to 10 m (33 ft), or a spreading shrub with a height and spread of 3-5 m (10-16 ft). It has juvenile-type foliage, with bands of blueish white stomata on the inside faces. This species is the source of juniper berries, the fleshy fruits used for flavoring gin. Cultivar 'Depressa Aurea' is a dwarf shrub to 50 cm (20 in) tall and 1.5 m (5 ft) across, with grace-fully pendulous branch tips which colour bronze-gold in winter, yellow in spring and greener in summer. 'Compressa' is a miniature which is column-shaped, rarely exceeding 50 cm (20 in) in height, with densely packed, dark green, small, prickly leaves. 'Hibernica', Irish juniper, the oldest and best known culti­var, grows to around 5 m (16 ft), forming a dense column of dull, blueish green foliage when young but taking on a broader conical shape with maturity.

J. conferta, Japanese shore juniper, zone 5, native to bleak, coastal areas of northern Japan and eastern Siberia, is a popular groundcover species in the UK and it will thrive in seaside as well as inland gardens. It is a prostrate species spreading to 2.5 m (8 ft) or more, eventually becoming a solid mat to a height of 30 cm (12 in). The juvenile foliage is fresh green in colour. It grows vigorously, but can be contained by trimming.

J. deppeana, alligator juniper, zone 8, from Mexico and southern North America, grows to 15 m (50 ft) or more in its habitat, but rarely taller than 6 m (20 ft) in cultivation. The bark of the trunk is divided into squarish shapes, hence the common name. It forms a conical shape, with a pointed crown and cypress-like foliage in a beautiful, silvery blueish gray colour. It prefers a relatively cool and dry climate.

J. horizontalis, creeping juniper, zone 4, from the north of North America, makes an excellent groundcover as it is very tough and spreads rapidly. Cultivars are available in a range of attractive colours, includ­ing 'Bar Harbor', which has small, erect, densely packed branches, the foliage turning a dull, deep mauve in winter; 'Douglasii', a very vigorous type, with a tangle of leading shoots and blueish gray foliage in summer, turning dull purplish in winter.

J. x pfitzeriana, zone 3, covers a group of cultivars probably parented by J. chinensis and J. sabina. All are spreading shrubs, and one or two semi-prostrate. Good cultivars include 'Gold Coast', 'Kuriwao Gold', 'Old Gold', and 'Pfitzeriana Aurea'. These all have gold or yellow foliage and are among the most popular cultivars of pfitzer juniper. Grow in full sun for best foliage colour.

J. procumbens, Japanese garden juniper, zone 8, from japan, is a prostrate, shrubby species, to 60 cm (24 in) high, the main branches being borne parallel to, and slightly above, the ground. Thick, flaky, pale brown bark covers the main branches. It has tufts of prickly, light green foliage and brown or black berries. J. sabina, savin, zone 3, a shrub from the mountains of Europe and Asia, a shrub, grows 3-4 m (10-13 ft) in height. Variety 'Tamariscifolia' is the type most grown in the US. It forms a dense mound of fine foliage, to 1 m (3 ft) high and 1.5 m (5 ft) across. The very small leaves are a dull, blueish green. This species will tolerate relatively warm and dry conditions.

J. scopulorum, Rocky Mountain juniper, zone 3, is native to the mountains of western North America. In its habitat, it forms a tree, to 12 m (40 ft), similar to J. virginiana. In the UK one of the most pop­ular cultivars is 'Skyrocket', which forms an extremely narrow column, to a height of about 6 m (20 ft). It is quite fast growing, so soon forms a pleasing specimen garden tree, decked in feathery, gray-green foliage.

J. squamata, zone 5, from the eastern Himalayas, is known mainly by its juvenile cultivar 'Meyeri', long cultivated in Chinese gardens and introduced to the west about a century ago. It is a beautiful form, with an erect, open habit, strong branches, pendulous at the tips, covered with steel blue, needle-like leaves. It generally grows to about 1.5 m (5 ft) but can reach 10 m (33 ft) with age.

J. virginiana, pencil cedar, zone 4, from eastern North America, grows 20 m (65 ft) in its habitat, though usually under 10 m (33 ft) in cultivation. It is a pyramid-shaped tree, with dull, grayish green foliage. Mature trees often exhibit juvenile foliage, especially around the lower parts of the tree. Cultivars worth growing include 'Gray Owl', a sizeable shrub to 3 m (10 ft), high with a spread of 3-4 m (10-13 it). The horizontal branches are clothed in silvery gray foliage. 'Hetzii' carries its branches in upward-pointing tiers, and reaches a height of 5 m (16 it), with a similar spread. It has an open habit of growth and blue-gray foliage.

Cultivation

As junipers are generally very hardy, they thrive in much of the UK. They are best grown in a position with full sun, although they will perform well in partial shade. They also do well in the dappled shade of trees, and indeed groundcover junipers are often planted under trees and large shrubs. The soil should be well drained. Chalky soils are particularly suitable, though not essential, for the plant's well-being. These plants will also take dry sandy or gravelly soils. Pruning is not essential but they can be trimmed annually if neat, bushy, com­pact plants are required. They tolerate trim­ming better than most conifers and many will even re-sprout from lopped ends of quite large branches. Nearly all junipers can be used as bonsai subjects. Propagate from cuttings taken in summer or early autumn from the current year's growth, with a heel of the previous year's wood. Dip cuttings in a hormone rooting powder, plant in a sand and peat propagating mixture and cover with an inverted glass jar or plastic hag to ensure humid conditions. Seed can also be used if available, but it requires cold treat­ment to ensure good germination. Cultivars must be grown from cuttings to retain their character.

Climate

There are species suited to various climatic zones.