A small succulent from the stony semi-desert of northern Somalia. Authority is Bally; the specific epithet cubiformis means "cube-shaped," and the species earns it — a chunky grey-green to grey-brown body grows into an almost perfect cube with hard angular faces and a coarse rocky surface. Leaves are virtually absent, and small dark purple-red star flowers bloom directly from the body in summer. The most sharply angular "stone mimic" in the genus and a signature collector species. Rots within days if overwatered, putting it among the hardest in the genus — strictly an advanced-grower plant.
Native climate
Very little rain falls all year — an arid setting. Overall a warm climate.
* Accurate distribution data is scarce for this species, so these values are taken from the climate near the approximate center of its native range instead.
Sources: climate & elevation WorldClim 2.1 (1970–2000) · occurrences GBIF · native range POWO · current weather Open-Meteo
Care
Light & Placement
In its native ground in northern Somalia, the species lives on stony semi-desert under intense sun and high heat. Through active growth, full direct sun outdoors keeps the angular cube body firm. Shade isn't needed in Japan's midsummer, but rain absolutely must be avoided — keep the pot on a bench with maximum airflow. Move indoors early as autumn cools, kept above 10°C and bone-dry.
Watering
In active growth, give very small amounts only after the substrate is fully dry. The species is the most overwatering-sensitive in the genus — slight under-watering is the safer side. A few days of damp pot collapses the body completely. Bone-dry through winter.
Substrate
Drainage first, with extremely coarse inorganic mix. Pumice : fine Kanuma : fine Akadama = 5:3:2 — pumice over half the volume — for a maximally fast-drying mix.
Fertilizer & Supplements
Almost none. A heavily diluted liquid feed once a month in active growth at most.
Temperature & Overwintering
Optimal 22–35°C with a 10°C minimum. Most cold-sensitive in the genus — branch tips die back near 5°C. Bring indoors early in autumn and overwinter bone-dry.
Starting from Seed
Where to source seeds
Pre-sowing treatment
Soak seeds for about half a day (overnight) 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. Anything still floating is unlikely to carry a viable embryo; freshness matters greatly.
Substrate
Use a separate seedling mix, fine and near-sterile: fine pumice, fine Kanuma, and vermiculite in 2:1:1 parts. Sterilize with boiling water or microwave first.
Sowing method
Sow with no covering. Space seeds at least 1 cm apart.
Light & temperature
Bright shade, 25–30°C steady. Expect germination in 14–30 days. Germination depends heavily on seed freshness, and even fresh seed stays on the lower side.
Watering
Bottom-water with the level only ~1 cm up the pot. Drop the level early to avoid damping-off.
Fertilizer
None for the first months after germination. Once true leaves emerge, a heavily diluted liquid feed once a month.
From Germination to Repotting
Germination through true leaves
Avoid overwatering at all costs; bright shade.
Weaning off bottom watering
Phase out within one month.
First repotting
In year 2–3, once the cube body has reached fingertip size.
Common Pitfalls
Mold & damping-off
- Cause: overwatering (the single biggest failure mode in the genus)
- Prevention: sterilize substrate, push pumice ratio higher, shorten the bottom-water period
Etiolation
- Cause: insufficient light
- Prevention: move LEDs closer right after germination, or shift the tray to bright shade outdoors
Seeds fail to germinate
- Cause: stale seed, insufficient warmth
- Prevention: source fresh seed and hold 25–30°C steady on a heat mat
Notes
A challenging advanced-grower species: rotted by the slightest overwatering, killed by autumn cold — bring indoors early. The sap is mildly toxic.
