A Commiphora that grows on the rocky hillsides of Namibia under sun and wind, weathering into the silvery blue-grey bark from which it takes its name — glaucescens means "becoming bluish". Engler described it in 1888 from northern and central Namibia, and the species ranges widely from the Kaokoveld outcrops to seasonal-drainage slopes and dry shrubland that bakes through the dry season. It is a deciduous small tree reaching 3–5 m, with a rounded canopy of arching branches and fine trifoliate leaves that give an old specimen the quiet bearing of an aged garden tree. The resin, leaves, and fruits all carry a sweet frankincense-like scent, and locally it has long been known as the "blue-leaved corkwood". Its bonsai-like form lends itself well to careful pot culture. IUCN conservation status: Least Concern.
Native climate
Rain concentrates in the warm season, with a dry season of roughly 6 months. Overall a mild climate.
A broad-scale picture of the native range. Real growing spots — rock crevices, fog belts — can be milder.
Sources: climate & elevation WorldClim 2.1 (1970–2000) · occurrences GBIF · native range POWO · current weather Open-Meteo
Care
Light & Placement
A plant of the rocky hills and seasonal-drainage slopes of Namibia, where it grows under strong sun with sharp day-night temperature swings. Place outdoors in full sun through the growing season — bright light tightens the trunk and brings out the blue-grey bark. Japan's hottest months tend to be manageable for this species, but a touch of afternoon shade on days well above 35°C helps prevent leaf burn. The plant dislikes wet conditions, so shelter under eaves from rain. Bring indoors to a bright window before temperatures fall below 8°C, holding warmth and low humidity. Airflow matters year-round.
Watering
In active growth, soak thoroughly once the topsoil has fully dried, then dry the surface quickly with good airflow. Withhold water completely through winter dormancy.
Substrate
A sharply draining inorganic mix: akadama : kanuma : pumice at 4:3:3. Sift out fines to avoid compaction and excess moisture. Deep pots help create clear wet-dry cycles.
Fertilizer & Supplements
A dilute liquid fertilizer once a month during active growth. Keep nitrogen low — excess softens trunk character and dulls the blue cast of the bark — and lean toward phosphorus and potassium.
Temperature & Overwintering
Optimal 20–35°C; this species is on the hardier side of the genus. Aim for an 8°C floor; brief dips below 5°C bring black blotches and soft rot. Hold fully dry indoors in a bright, warm spot through winter.
Starting from Seed
Where to source seeds
Pre-sowing treatment
Soak seeds for about 7 hours in a mix of a registered seed-treatment fungicide (Benlate or Daconil) and a plant tonic (Menedael; outside Japan, SUPERthrive or a chelated iron / seaweed extract works similarly), each diluted per label. Freshness strongly governs germination — old seed lots may turn out to be empty, so source recent seed and sow promptly.
Substrate
A fine-grained inorganic mix — fine akadama and fine hyuga at roughly equal parts. Sterilize with boiling water or a brief microwave pass before sowing.
Sowing method
Level the surface and lay seeds on their sides. Cover with the thinnest dusting of substrate, just enough that the seeds remain faintly visible. Avoid deep sowing.
Light & temperature
Bright shade out of direct sun, with temperatures held at 25–32°C. Germination takes 7–21 days. Germination depends on seed freshness, but with fresh seed it is reasonably steady. A heat mat helps stabilize temperatures.
Watering
Bottom-water continuously until germination to keep the mix evenly moist. Once seedlings are up, shift to shallow bottom watering to encourage root extension.
Fertilizer
Once two or three true leaves have emerged, apply a liquid feed diluted to less than half strength, monthly. Stronger doses burn fine roots.
From Germination to Repotting
Germination through true leaves
Continue bottom watering and keep humidity up.
Weaning off bottom watering
Wean gradually over 1–2 months.
First repotting
Year 1–2, once roots have filled the pot.
Common Pitfalls
Mold & damping-off
- Cause: Excess moisture, microbes, poor airflow
- Prevention: Sterilize the substrate, ensure ventilation, shelter from rain
Etiolation
- Cause: Low light, excess fertilizer
- Prevention: Full sun in growing season, keep nitrogen low
Seeds not germinating
- Cause: Stale seed, insufficient heat
- Prevention: Use fresh seed, use a heat mat
Notes
The sap is mildly toxic. Soft rot appears below 5°C.
