How to grow and care for juniper trees

Juniper is in decline in wild populations and has been designated a UK Biodiversity Action Plan priority species. This special tree has disappeared from several areas in the south of England. Many remaining colonies are so small that they're considered functionally extinct. Scotland is now the stronghold for 80 per cent of the UK’s juniper trees.

Juniper has been important to humans for millennia for its culinary, medicinal and ritual properties. It was believed that the aromatic smoke of burning juniper would purify temples and offer protection from the plague. Juniper has been valued in traditional medicine for treating a wide range of complaints.

How to grow a juniper tree

Juniper can develop in one of two ways – either as a columnar form that creates architectural structure in the garden, or as a spreading form that works well as ground cover. Both types of juniper are suitable for UK gardens. Juniper is hardy and drought-resistant, making it a good choice for free-draining soils, dry regions and coastal areas.

Identifying juniper

Juniper trees have dark grey-green, aromatic, needle-like leaves that taper to sharp points, arranged in whorls of three along the stem. Juniper bark is grey-brown on larger branches and reddish-brown on twigs. It has a tendency to peel off in long shreds. Juniper is a dioecious conifer, which means that male and female cones grow on separate plants. Male cones are small and yellowish, and female cones are fleshy, berry-like structures that ripen from green to blue-black over a period of around 18 months to two years.

The female cones of common juniper (Juniperus communis) are usually referred to as ‘juniper berries’ and have traditionally been used for flavouring gin. All juniper species apart from common juniper have toxic berries, although the common juniper can be toxic in large amounts. Do not use common juniper berries if you are pregnant or have kidney disease.

Size: height and spread

Common juniper trees can grow to around 8m tall. Many species and varieties are much smaller, some only reaching 10cm in height. Prostrate juniper can spread up to 4m. Trees are slow growing and can live for up to 200 years, although the average lifespan is 100-120 years.

Value to wildlife

Many species of fungi and over 40 plant-eating insects are associated with juniper, including the juniper carpet moth and the juniper shield bug. Juniper bushes provide dense prickly cover in which small birds such as stonechats nest, and its berry-like female cones are eaten by birds such as the mistle thrush.

Where to plant a juniper tree

Juniper grows best in moist but free-draining soil in full sun or partial shade. Dry, chalky and sandy soils are all suitable for juniper trees, and they're unusual in their ability to tolerate both acid and alkaline conditions. They're ideal for wildlife gardens and coastal situations.

How to plant juniper

Plant juniper trees between late October and March as long as the soil isn’t waterlogged or frozen. Juniper foliage can cause skin and eye irritation, so it's advisable to wear gloves and other protective equipment when handling plants.

1. Choose an area with free-draining soil and loosen soil in planting area if necessary
2. Dig a square hole the same depth as the rootball and twice as wide
3. Soak the rootball in a bucket of water before planting
4. Loosen roots and ensure the top of the rootball sits level with the soil
5. Refill the hole with soil and firm gently
6. Water well after planting and water in dry periods for the first couple of years

How to care for a juniper tree

Once established, these low-maintenance plants don’t require watering or feeding. Add a mulch around the base (avoid mulching directly up against the trunk) in late winter or early spring to suppress weeds and retain moisture.

How to prune juniper

Juniper trees require no routine pruning. If you do decide to create topiary with juniper, it's important to avoid cutting into dead wood. Dead branches should be pruned right back.

Pests and diseases

Juniper can host a range of specialist insects, including aphids, caterpillars and scale insects, which shouldn’t cause significant problems unless infestations are particularly heavy. Many of these insects provide a good source of food for birds.

Studies suggest the decline of wild juniper populations could be partly due to browsing by livestock, deer and rabbits. Juniper is also susceptible to fungal infections from canker, honey fungus and Phytophthora root rot, in particular Phytophthora austrocedrae, which can kill juniper trees.

Eight types of juniper to grow

Juniperus chinensis 'Blue Alps’

This attractive Chinese juniper can reach 4m in height. It grows into an aromatic shrub or small tree with steely blue, prickly foliage and a robust upright habit.

• Buy Juniperus chinensis 'Blue Alps' from Gardenersdream, Paramount Plants, Suttons and Thompson & Morgan

Juniperus communis ‘Gold Cone’

‘Gold Cone’ has yellowy-green needles that turn a vivid golden yellow in winter. With a compact, conical habit (only reaching around 1.5m in height), this juniper is ideal to add evergreen interest to beds and borders.

• Buy Juniperus communis ‘Gold Cone’ from Gardenersdream, Jacksons Nurseries, Suttons and Thompson & Morgan

Juniperus communis ‘Green Carpet’

This prostrate variety of juniper is excellent as a mat-forming plant in rockeries, borders and on slopes. Only reaching 10cm high, it'll spread for a metre or more, providing year-round evergreen ground cover.

• Buy Juniperus communis ‘Green Carpet’ from Crocus, Langthorns Plantery, Suttons and Thompson & Morgan

Juniperus communis ‘Hibernica’

Also known as Irish juniper, this columnar conifer should grow to around 3m tall over a 20-year period. ‘Hibernica’ is perfect to create architectural structure, even in smaller gardens.

• Buy Juniperus communis ‘Hibernica’ from Arundel Arboretum, Dobies, Paramount Plants and Thompson & Morgan

Juniperus communis ‘Repanda’

Another prostrate, mat-forming variety, ‘Repanda’ has soft evergreen needles that take on a bronze hue in the autumn and winter. It'll grow 40-50cm in height and spread around 2m.

• Buy Juniperus communis ‘Repanda’ from Burncoose Nurseries, Crocus, Mail Order Trees and Paramount Plants

Juniperus sabina ‘Tamariscifolia’

The tamarisk-leaved savin is a spreading juniper reaching 1.5m in height and 2.5m spread over 20 years. Great as a ground-cover plant on banks and slopes.

• Buy Juniperus sabina ‘Tamariscifolia’ from Ashwood Nurseries, Dobies, Ornamental Trees and Thompson & Morgan

Juniperus scopulorum ‘Blue Arrow’

Ideal for small gardens, the Rocky Mountain juniper only grows to 2.5m in height and maintains a narrow, upright habit. With silvery-blue fragrant foliage, ‘Blue Arrow’ can be grown as a specimen tree to create a dramatic focal point or planted in groups to add formality and evergreen interest to your garden.

• Buy Juniperus scopulorum ‘Blue Arrow’ from Crocus, Frank P Matthews, Kelways and Thompson & Morgan

Juniperus squamata ‘Blue Carpet’

This low-growing variety, also known as flaky juniper, has spiky blue-green foliage that develops even bluer shades in the winter. ‘Blue Carpet’ is a low-maintenance, vigorous conifer that grows around 30cm in height and spreads around 2.5m.

• Buy Juniperus squamata ‘Blue Carpet’ from Langthorns Plantery, Ornamental Trees and Suttons