Juniperus

Blue star juniper is native to the Himalayas and north-west China’s mountains at elevations between 1600-4800m. Its habit is variable, like most other junipers: it can grow as a small tree or as a prostrate creeper, but most commonly is an erect shrub.

The blue star’s branch tips droop attractively. The bluish needle leaves – varying in shade from blue-green to strongly bluish - are in groups of three, broad and curved, with sharp tips. In colder months they take on shades of brown and bronze.

The berry-like cone is oval, black when ripe, and contains a single seed; most others juniper cones usually contain more than one.

Not many wild forms of blue star juniper are in production but there are numerous cultivated varieties available, which vary in size and habit. The first plant to be taken into cultivation was a beautiful steel blue, found in the early 1900s by Frank Meyer and know by the varietal name ‘Meyeri’.

Creeping juniper grows naturally over a large area of northern North America, from Newfoundland to near the Arctic Ocean, on rocky shores, in the mountains, in nutrient-poor forests and on bogs. It is hardy to heat and cold, enjoys full sun but also tolerates a degree of shade.

Creeping juniper grows in low ground-covering thickets and its long snakily twisting stems take root easily. It has both needle-like young leaves and soft scale-like mature leaves, varying in shade from dark green to blue-green. The species is usually dioecious, i.e. the male and female flowers are on separate plants; the berry-like cones of the female plants are dark blue.

Creeping juniper is a very popular ornamental due to its low habit. Previously, individual plants were selected direct from the wild for their attractive colour or habit. Nowadays an enormous number of varieties are in production.

Rocky Mountain juniper grows throughout the mountainous areas of western North America, mainly above 1500 metres elevation. In places it forms large thickets giving a characteristic appearance to the landscape. It can grow into an erect, pillar-shaped or conical tree to 10 metres, or an irregular round shrub with strong branching from the base.

Rocky Mountain juniper has two kinds of leaves, one kind being needle-like, the other scale-like and pressing close to the branches. Their colour varies from dark blue-green to a dull grey-green. The species is usually dioecious, i.e. each individual is either male or female. The berry-like cones borne by the females are roundish, clear blue, with a surface bloom. This species is extremely long-living: a tall tree-like specimen found in New Mexico had 1888 annual rings.

Rocky Mountain juniper’s hardiness in Finland has not been properly tested. Those plants grown here are usually pillar-shaped or other attractive varieties, which at Mustila seem to thrive better than the wild species. The most commonly grown variety in Finland is probably ‘Skyrocket’, often named J. virginiana. 'Blue Arrow', 'Moonglow', 'Silver Star', 'Springbank' and 'Wichita Blue' are other varieties planted at the Arboretum.