Rocky Mountain Juniper (Juniperus scopulorum) Bonsai Care Timeline
Rocky Mountain Juniper (Juniperus scopulorum) is an evergreen conifer native to western North America, from British Columbia and Alberta south to Arizona, New Mexico and western Texas (and into northern Mexico), east to the Dakotas. It grows on dry, rocky slopes, canyons, and high plains, from near sea level around Puget Sound to about 9,000 feet, often in pinyon-juniper woodlands with full sun and poor soils, typically reaching 15–40 feet tall (occasionally taller) with a conical to irregular form, scale-like foliage, and reddish-brown bark that shreds in strips.
It is drought- and cold-tolerant, with blue-green foliage and small blue berries on female trees. In bonsai, Rocky Mountain Juniper is one of the best North American junipers for its fine scale foliage, prolific deadwood, and rugged character, suiting windswept, literati, or upright styles. It is popular in the USA for Rocky Mountain yamadori. In USDA Zone 7 it is hardy outdoors with full sun and sharp drainage.
Evergreen conifer; outdoor in Zone 7.
- Type: Evergreen conifer; outdoor in Zone 7.
- Light: Full sun.
- Watering: Every 2–4 days when topsoil dries.
Skip to a season:
Spring (Mid-March – Mid-May)Summer (Mid-May – August)Fall (September – Mid-November)Winter (Mid-November – Early March)
Spring (Mid-March – Mid-May)
Goal: Promote dense new growth.
- Light: Full sun.
- Watering: Every 2–4 days when topsoil dries.
- Fertilizing: Balanced organic every 3–4 weeks from mid-April.
- Pruning: Cut extending shoots back to a fork with scissors; thin pads with scissors at the base; never remove all growing tips.
- Wiring: Light wiring only; avoid heavy bending while new growth is soft (bark slips easily).
- Repotting: Every 3–5 years early spring; high-drainage mix. Collected yamadori are slow and finicky after collection — keep root work conservative and mist the foliage after repotting.
- Pests/Diseases: Spider mites, bagworms; neem preventive. Tip blight (Phomopsis/Kabatina) in wet springs — prune out dead tips well below the infection, disinfect tools, copper fungicide preventively; cedar rusts — remove galls in spring.
- Notes: Excellent drainage essential.
Summer (Mid-May – August)
Goal: Maintain compact foliage.
- Light: Full sun.
- Watering: Daily in heat.
- Fertilizing: Balanced; reduce in extreme heat.
- Pruning: Cut extending shoots back to a fork with scissors; thin pads with scissors at the base; never remove all growing tips.
- Wiring: Check wire monthly.
- Repotting: Avoid.
- Pests/Diseases: Mites; hose foliage.
- Notes: Drought-tolerant once established.
Fall (September – Mid-November)
Goal: Refine structure.
- Light: Full sun.
- Watering: Every 3–5 days.
- Fertilizing: Low-nitrogen in September; stop mid-October.
- Pruning: Light thinning.
- Wiring: Ideal for major wiring/styling.
- Repotting: Avoid.
- Pests/Diseases: Tip blight (Phomopsis/Kabatina) — prune out dead tips well below the infection, disinfect tools, copper fungicide preventively; cedar rusts — remove any galls.
- Notes: Blue berries on females.
Winter (Mid-November – Early March)
Goal: Dormancy.
- Light: Sunny shelter.
- Watering: Every 7–14 days.
- Fertilizing: None.
- Pruning: Minimal.
- Wiring: Wire OK with care; avoid heavy bends in deep cold (branches brittle).
- Pests/Diseases: Inspect inner foliage for scale and overwintering spider mites; horticultural oil on a mild day if found.
- Protection: Mulch pot; hardy.
- Notes: Very cold-tolerant. Foliage may bronze or turn purplish-brown in frost — normal frost protection; it greens up again in spring.
Zone 7 Tips: Full sun and sharp drainage; excellent native juniper for deadwood and rugged style.
Supplies for your trees
These guides are how we grow our own trees — and the supplies we use are the ones we sell: Bonsai Shoes training pots · Wire Condo wire caddies · Bonsai trees & pre-bonsai · Bonsai soil. Questions about your tree? Contact us.