From groundcover to tree: with its varied varieties, Juniper is a versatile, decorative, woody addition to any garden. It’s also a popular seasoning and is valued as a healing plant. Here’s how to cultivate this plant – from planting to harvest.
Juniper (Juniperus), along with its 70 species, is part of the Cupresaceae family of conifers, where it forms the largest group. Since ancient times, Juniper has been very important as a spice and healing plant. In the Middle Ages, juniper smoke was used to discourage illness as well as ward off witches and demons. Juniper extracts are still used today to treat UTIs and stomach problems. The fruit of this tree or shrub, the Juniper berry, is a popular culinary ingredient.
Appearance and Growth
Depending on the species, Junipers may be a creeping shrub or an evergreen tree. The four to six-bladed branches feature small, densely arranged leaves. These are needle-like, extremely pointed and arranged in threes or fours, forming little whorls that look like green stars. Juniper berries are actually small cones. This is easiest to spot when they are still green and unripe. The seed heads form after fruiting, from the fused seed and covering scale of the female cone. Juniper is dioecious. If you want to harvest fruit, you will have to plant a male and at least one female - and be patient, as it can take up to seven years for the female Juniper to flower for the first time. It can then take another two years for the berries to ripen. The fruits and needles of almost all Juniper species are toxic, with the single exception of the dark blue berries found on common Juniper (Juniperus communis).
Location and Soil
All Junipers are very adaptable and grow in subarctic as well as subtropical areas. Juniper thrives in sunny and partially shaded locations in permeable soil that may also contain lime. It can tolerate heat and drought exceptionally well but will suffer in the shade (e.g. under a large tree canopy) as it requires plenty of light.
Early fall is the best time to plant evergreen conifers with root balls. Garden soil retains a relatively high level of heat until mid November. Thanks to these energy reserves, the freshly planted shrubs can root slightly even in the year of planting. This is important, as evergreens evaporate water from their needles even in winter, and only a well-established root network can replace the moisture required. Depending on growth type (groundcover, shrubby or upright), junipers need varying amounts of space. If you want to use Juniper as a hedge, you should leave at least 2.3 feet between the plants.
Juniper is very low-maintenance. It needs to be watered when dry only for the first few years: older plants will get by fine without additional watering. Regular feeding with long-term conifer fertilizer supports the plant’s robust nature.
Juniper tolerates pruning well and can be shaped at any time of year, but ideally in spring or fall. The old wood is very hard to get rid of. Note: its pointed needles make Juniper a very resilient plant. So always wear long sleeves and sturdy gloves when pruning!
Well-rooted Juniper plants are completely winter hardy and need no protection in winter.
Various Juniper species and varieties create diversity in the garden, catching the eye all year round thanks to their great variety. There is the perfect plant for any size garden size in the Juniper genus. Slow-growing Juniper varieties are particularly suited to domestic gardens. Smaller varieties can also be planted in containers and pots, as even bitter frost will not impact them much. Creeping Junipers come with yellow, blue and green needles (e.g. “Hornibrokii”), and their slow growth makes them perfect for smaller gardens and sunny plots. It spreads out like a carpet and is ideal as a low-growing border edge. Juniper shrubs grow rapidly and tolerate pruning well (such as uniperus virginiana “Hetzii” and “Pfitzeriana” varieties). It also thrives in pots, developing the Juniper berries that are beloved as a spice. Columnar Juniper, such as “Skyrocket” and “Hibernica”, are typical plants for heather gardens and are often planted instead of cypress at temperate latitudes. Due to its slim growth, it is ideal for small front yards, around boulders and next to graves.
Tip: Juniper branches are toxic but give off a lovely resinous smell in the home. Juniper berries are harvested from August into late fall. The pointy needles make it very difficult to pick by hand, so the berries are knocked from the branches with a stick. Juniper chips are suitable for smoking and barbecuing, and are also used in baths and as a natural moth repellent. Juniper berries are used to flavor various alcoholic drinks such as gin and jenever.
Important Species and Varieties
The wild variety of Juniper is seldom used in domestic gardens. Here, cultivated varieties are preferred because of their more compact growth. Possible alternatives, including for harsher locations, are columnar junipers such as Juniperus chinensis “Spartan” or “Keteleeri” or even Juniperus scopulorum “Skyrocket”, which grows several feet high but remains extremely slim, so it only requires minimal space to grow. Thanks to its ground-hugging growth, creeping Juniper (such as Juniperus procumbens “Nana”, Juniperus horizentalis “Glauca” and Juniperus squamata “Blue Carpet”) is ideal for greening a large amount of space. Dwarf Juniper (Juniperus chinensis ‘Stricta’) has a less formal appearance. Its needles turn a steely blue in winter, and really catch the eye. The needles of the flaky juniper (Juniperus squamata “Blue Star”) also feature a lovely shade of blue. The Yellow Juniper Juniperus media “Old Gold” has golden yellow needles all year round. Chinese Juniper “Rockery Gem” will add a leafy green to your garden. Its growth is low and its branches are strongly branched. Low-growing Creeping Juniper (Juniperus horizontalis “Bar Harbour”) is like a blue rug, taking on a purple shimmer in the fall.
It’s best to propagate Juniper in summer using cuttings. Some, particular creeping varieties, can also be propagated through layering. Cultivated varieties are developed in nurseries through grafting. Propagation through seeds usually does not work.
Diseases and Pests
Juniper rarely falls foul to disease and pests, but it can carry pear rust. Savin Juniper, Chinese Juniper and Red Cedar are the main carriers of this fungus. Common Juniper (Juniperus communis) is not affected. This fungal disease takes hold on its main host in spring, forming gelatinous winter sporocarps on thickened shoots (galls). In rainy periods, a multitude of fungal spores is released and carried on the wind to its secondary host, the pear tree. Here, small orange-red spots appear on the leaves during its flowering period along with wart-like growths on the underside of the leaf, where new fungal spores form. The pear tree will no longer bear fruit and will die if the infection becomes serious. To prevent an infection, you should keep these two plants as far apart from each other as possible. During flowering season, three to five sprays with plant protection products should help. The only treatment for Juniper is drastic pruning back to the healthy wood. Do not put the cuttings into your compost, rather dispose of it with general household waste.