Juniperus scopulorum ‘Blue Arrow’ (Rocky Mountain Juniper)

Juniperus scopulorum ‘Blue Arrow’ (Rocky Mountain Juniper) is a popular choice for its distinctive vertical form and vibrant blue-green foliage, adding architectural interest to a wide range of garden designs.

Juniperus scopulorum ‘Blue Arrow’: An In-depth Look

Juniperus scopulorum ‘Blue Arrow’ is a slender, upright juniper, prized for its dense, columnar shape and striking blue-green foliage.

Native: The species Juniperus scopulorum, commonly known as Rocky Mountain Juniper, is native to western North America, from southwest Canada to the Great Plains of the United States.

Plant Type and Habit: This is an evergreen conifer with a very upright, columnar growth habit, making it ideal for narrow spaces.

Size: ‘Blue Arrow’ typically grows to about 12-15 feet in height (3.6 to 4.5 meters) and 1-2 feet in spread (30-60 cm), offering a slender vertical accent.

Cones: Junipers are dioecious with separate male and female plants. Male plants produce small pollen cones, while pollinated female plants produce small, blue-black berry-like cones, adding winter interest.

Foliage: The foliage consists of tightly packed, blue-green needles, providing a striking color year-round.

Bark: The bark is typically a gray-brown color, becoming more textured with age.

Uses: Ideal for creating vertical interest in landscapes, used as a specimen plant, in narrow spaces, or for privacy screens and hedges. Perfect for city gardens since Rocky Mountain Juniper is tolerant of pollution.

Award: Recipient of the prestigious Award of Garden Merit of the Royal Horticultural Society.

Hardiness: It is hardy in USDA zones 4-9, adaptable to a range of environmental conditions. It does not perform well in high humidity, or high night temperatures. It is also intolerant to ice.

Wildlife: Provides limited attraction for wildlife, though birds may feed on the cones.

Toxicity: Junipers are generally not toxic, but the cones can cause mild stomach upset if ingested in large quantities. Foliage may cause skin irritation. Wear gloves and other protective equipment when handling.

Deer and Rabbit: Relatively resistant to deer and rabbits, which makes it suitable for areas where these animals are a concern.

Drought: Once established, it has a good tolerance for drought conditions, making it a good choice for water-efficient landscapes.

Salt: Exhibits moderate salt tolerance, making it suitable for planting in coastal areas or landscapes where saline soil or salt spray may be present.

Invasiveness: This Juniper is not considered invasive. It grows in a controlled manner, maintaining its narrow form.

Benefits: Provides year-round visual interest with minimal maintenance and is particularly useful for adding vertical elements in landscaping.

Rocky Mountain Juniper Growing Tips

Light: Prefers full sun for optimal growth and health. Can tolerate light shade but may have reduced foliage density.

Soil: Thrives in well-drained soil. Adaptable to a wide range of soil types, including clay, loam, and sandy soils. Tolerates dry, rocky soils and does not perform well in wet soils.

Water: Requires moderate watering, especially when young. Established plants are relatively drought-tolerant. Ensure proper drainage to prevent root rot. Overwatering should be avoided.

Fertilizer: Light fertilization can be done in spring with a balanced, slow-release fertilizer. Avoid over-fertilizing, which can harm the plant.

Pruning: Minimal pruning is required, mostly for shaping or size control. Best pruned in late winter or early spring.

Propagation: Propagated through semi-hardwood cuttings, typically in summer.

Pests and Diseases: Junipers are often prone to twig blight and needle blight. They also act as hosts for cedar-apple rust and similar rust diseases during part of their lifecycle. In wet, poorly drained soils, root rot can be a problem. Additionally, they may occasionally suffer from insect pests like aphids, bagworms, webworms, spider mites and scale insects.