Skyrocket juniper

Sun

Full sun; shade produces looser growth and poorer foliage colour.

Water

Water regularly while establishing; drought tolerant once rooted. Avoid persistently wet soil.

Soil

Well-drained sandy, gravelly or loamy soil; tolerates alkaline conditions. Heavy clay is suitable only where drainage is good.

Height

15-20 ft (4.5-6 m), sometimes taller with age

Spread

2-3 ft (0.6-0.9 m), sometimes wider with age

Foliage

Evergreen. Dense, blue-grey to silvery-blue foliage, mainly small overlapping scales; young shoots may carry sharper, needle-like leaves.

Growth

Moderate, commonly 6-12 in (15-30 cm) a year once established.

Care needed

Low

• Deer resistant
• Drought tolerant
• Cold hardy
• Wildlife

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   7 ft (2 m)

2. After 1 year

   7 ft (2.2 m)

3. After 2 years

   8 ft (2.3 m)

4. After 3 years

   8 ft (2.5 m)

5. After 5 years

   9 ft (2.8 m)

About 20 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Mildly toxic: may upset a stomach

Native to

the US and Canada

Growth rate

Moderate

• Water deeply during dry spells for the first two growing seasons; let the soil begin to dry between waterings.
• Plant with the root flare at soil level and avoid sites where winter water collects.
• Apply 2-3 in (5-8 cm) of mulch over the root area, keeping it clear of the trunk.
• Do not feed routinely; use a modest spring application of balanced fertiliser only if growth is weak and a nutrient shortage is likely.
• Allow space between plants for air circulation rather than crowding them into an immediately solid screen.
• Gently brush off loose snow before it freezes onto branches; do not strike or pull frozen branches.

Pruning. In late spring or early summer, lightly shorten stray green shoots if needed to preserve the narrow outline. Remove dead or damaged branches promptly, but do not cut back into bare old wood because it rarely regrows.

Late winter

Inspect for snow or wind damage and remove broken branches during frost-free weather.

Spring

Plant when the ground is workable, water thoroughly and mulch without covering the trunk base.

Late spring

Check shoot tips for dieback and lightly trim any branches that spoil the outline.

Summer

Water young plants during dry spells and check bronzing foliage for spider mites.

Autumn

Water before the ground freezes if autumn has been dry, especially for recently planted trees.

• Place a matching pair beside a sunny entrance or gateway to create upright markers.
• Repeat along a boundary for a narrow evergreen screen, allowing for the mature spread.
• Use among low grasses, lavender and gravel to contrast slender blue columns with soft, spreading forms.
• Set behind low shrubs in a small sunny border to provide height without a broad canopy.

Garden styles it suits: Architectural minimal, Formal, Contemporary minimal, Dry gravel garden, Desert / xeriscape and Winter interest.

Plant it with: English lavender, Russian sage, Catmint, Blue fescue, Creeping thyme and Stonecrop.

Wildlife: Dense evergreen branches provide shelter and potential nesting cover for small birds. Junipers can also support insects and mites eaten by birds.

• Root rot in waterlogged soil: improve drainage before planting; severely affected trees usually need replacing in a better-drained position.
• Juniper tip blight: prune out dead shoot tips in dry weather, clean tools between cuts and avoid overhead watering.
• Spider mites causing fine stippling and bronzing: confirm by tapping a branch over white paper, then wash foliage with water; use a labelled mite treatment if damage continues.
• Branches splaying under wet snow: remove loose snow gently and have badly split stems assessed; preventive, loose seasonal support may help exposed multi-stemmed plants.

Rocky Mountain juniper is reported to have low-severity toxicity if eaten: foliage and berry-like cones may cause digestive upset in people, and foliage can irritate sensitive skin. Reliable toxicity information specific to this cultivar in cats, dogs and horses is limited; prevent substantial ingestion and seek veterinary advice if an animal develops symptoms. Do not use its cones as culinary juniper berries.

• Blue Arrow juniper (Juniperus scopulorum 'Blue Arrow')

  Usually has tighter, more closely held branches and a denser, slimmer outline. Young plants can be difficult to distinguish reliably without a label.

• Italian cypress (Cupressus sempervirens)

  Upright forms have a similar columnar silhouette but generally darker green foliage and much larger, woody, rounded cones rather than small berry-like juniper cones.

• Pencil Point juniper (Juniperus communis 'Compressa')

  A much smaller, slower-growing column with prickly needle leaves marked by pale bands, rather than predominantly scale-like blue-grey foliage.

Juniperus is the Latin name for juniper, scopulorum means 'of rocky places', and 'Skyrocket' describes the cultivar's slender, upward-reaching shape.

Propagation. Take semi-ripe cuttings with a small heel in late summer or autumn and root in a freely draining medium under protected conditions. Rooting can be slow; seed will not reliably reproduce the cultivar.

Accepted botanical name

Juniperus scopulorum

In the US and Canada

Native in Canada and the lower 48 states.

Native range

Alberta, Arizona, British Columbia, Colorado, Idaho, Mexico Northeast, Mexico Northwest, Montana, Nebraska, Nevada, New Mexico and North Dakota.

Measured

Soil pH 5 to 8.5. Average height 1200 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.