624 Juniperus horizontalisCommon Names: creeping juniper, trailing juniper, creeping savin juniper, creeping cedar Family: Cupressaceae (cypress Family)
Creeping juniper is an evergreen ground cover with soft, fine-textured plume-like foliage. It has long spreading branches, and short twigs that stand upright to form a mat about a 1 ft (0.3 m) high. A single plant can cover an area 6-10 ft (1.8-3.1 m) in diameter. The leaves on new shoots are needle-like and sharp-pointed. On older growth the leaves are elliptic and scale-like, and lie flat and overlapping in four rows on the twigs. In cold weather creeping juniper often changes to an overall purplish color. Creeping juniper is dioecious (separate male and female plants). Male cones are about 1/4 in (0.6 cm) in diameter, yellow and dry. Female cones are berry-like and fleshy, dark blue, and contain 1-3 seeds.
At least 60 cultivars have been selected. Probably the most popular is 'Wiltonii', also known as 'Blue Rug'. It stays less than 6 in (15.2 cm) tall, and has glaucus (with a powdery bloom) foliage that is bright steel blue-green in summer, becoming mauve in winter. 'Plumosa' is taller, to 2 ft (0.6 m), with needlelike leaves only. It has gray-green foliage in summer, turning purplish bronze in winter. 'Blue Chip' has foliage that is almost truly blue. 'Hughs' has silvery-blue foliage, and is particularly dense and flat-topped. 'Glauca' is very flat, less than 3 in (0.9 cm) tall, with blue-gray foliage that is tinged purple in winter. 'Bar Harbor' is steel blue in summer and plum colored in winter. It is more tolerant of salt spray.
Juniperus horizontalis, the creeping juniper, occurs naturally in open dry, sandy and rocky habitats in northern North America from Newfoundland to Alaska, and south to Wyoming, Nebraska, northern Illinois and northern New York. It's a common shrub in the Adirondacks, growing between the rocks in the boulder-strewn drumlins left by retreating glaciers 8,000 years ago.
CultureCreeping juniper will grow in acidic to slightly alkaline soils. It can grow about 15 in (4.6 cm) a year. Prune young shoots to encourage branching, but older branches may not produce new growth when pruned. Light: Full sun is best. Tolerates partial shade, but foliage will be thinner. Moisture: Established plants are highly drought tolerant. Hardiness: USDA Zones 3 - 10. Grows well up to 8000 ft (2438 m) in Colorado. Propagation: Juniper seeds can take up to 5 years or more to germinate. Several treatments to speed up the process have been tried with limited success: pre-chilling, soaking in hot water, soaking in an oxygen-saturated solution of gibberellin, soaking in sulfuric acid, soaking in citric acid, and surgically removing parts of the seed coat! (It is not clear whether conferring with the Juniper shaman has been adequately tested.) Suffice it to say, most people propagate junipers from cuttings. In the summer, start softwood cuttings under mist (use a fungicide) and supply bottom heat. Ripe-wood cuttings taken in fall and winter can be started without the mist or bottom heat. Creeping juniper also can be propagated by layering: Girdle a young, fast-growing stem about 10 in (25.4 cm) back from the tip, bend it up, and bury the girdled part in the ground. It may take several months for roots to form before you can sever the layered stem from the parent. Leave it in place for a few more weeks. Then prune off the growing tip to encourage the new roots even more. Eventually, you should be able to dig up the new plant and replant it where you need it.
Creeping juniper is used throughout the U.S. and probably is the most common evergreen groundcover, available in retail outlets everywhere. Creeping juniper tolerates hot and dry conditions, clayey, sandy, gravelly and compacted soils, salt spray, air pollution, and urban conditions. (It does not like to be trod upon, however.) Use it anywhere (in sun) you need a ground cover. Let it cascade over walls and down slopes. Its one drawback is that grass and weeds often find a way to poke through the foliage. Some gardeners grow creeping cedar in hanging baskets. It also is used in bonsai.
In its native range, the foliage and fruits are eaten by moose, deer and grouse. (Gardeners in zones 6-10 have reported little predation by moose, however.) There are about 70 species of Juniperus in North America, Europe and Asia, some even in the arctic. Red cedar is a juniper (J. virginiana). Common juniper (J. communis) is the source of the berries that give gin its distinctive flavor.
Native Americans, including the Blackfoot, Cheyenne, Crow, and Ojibwa, made tea from the berry-like fruits and used infusions to treat kidney diseases, colds and sore throats. They also burned creeping juniper as incense in ceremonies. Modern herbalists use essential oils from the related J. communis to treat urinary tract infections, and claim it is useful in treating rheumatism, arthritis and gout.
Steve Christman 12/19/99; updated 6/10/04