A small caudiciform Pelargonium from the fog belt of the southern Namib in Namibia's Karas Region, ranging about 300 km south along the coast as far as the Orange River in South Africa's Northern Cape. Short, fat dark-brown stems branch densely into finger-like twigs that carry small grey-silver woolly fan-shaped leaves and white to pale-pink flowers from autumn through spring; in summer the plant drops its leaves and rests as a winter-grower. Kew POWO treats P. crassicaule L'Hér. (1789) as the accepted name, which this site adopts (Dinter's P. mirabile (1920) is nom. illeg.). Seed and plants continue to circulate in horticultural trade under the mirabile name. In Japan it is also known affectionately as karintō — for the resemblance to a knobby brown sugar candy — and remains a favourite among caudex collectors.
Native climate
Almost no rain falls all year — a hyper-arid setting. 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
The native habitat receives less than 100 mm of rain a year, almost all of it in winter, supplemented by frequent fog from the cold Benguela current; plants wedge into cracks of quartz, granite-gneiss and sandstone outcrops under intense sun but cool air. During the autumn-to-spring active season in Japan, give as much bright outdoor or windowsill light as possible — strong light keeps branches short and the dark-brown bark and silver leaf-down crisp. The dangerous season is summer after the rainy season: shift to bright shade out of direct sun (50–70% shade cloth), raise the pot on a bench, and run a circulation fan. Winter indoors above 5°C on a bright windowsill is straightforward.
Watering
Restart watering in small amounts from September into October, then water properly when the substrate has dried once leaves are out. Cut water in May–June once leaves yellow and drop, and keep dry through summer. Watering in summer because the plant looks "too dry" is the single most reliable way to lose it.
Substrate
Drainage first, inorganic-led. Akadama : Kanuma : pumice = 3:3:4, leaning on pumice to dry faster. Habitat is shallow rock cracks, so a shallow pot that dries from the surface down works better than a deep one.
Fertilizer & Supplements
Liquid feed at heavy dilution once a month through the active season, or a pinch of slow-release at repotting. Native soils are extremely poor; pushing fertilizer elongates branches and dulls the bark. Nothing through summer.
Temperature & Overwintering
Optimal 15–25°C; minimum around 5°C. When dry the plant tolerates close to 0°C, but damp soil under cold is fatal. Summering is harder than overwintering: tropical nights above 35°C combined with humidity will rot the base. Keep summer on shade, ventilation and complete dryness; an air-conditioned room is a legitimate retreat.
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. Floaters are typically past their prime. Seeds are typical Geraniaceae achenes with a feathered awn; viability drops with age.
Substrate
A separate seedling mix, fine-grained and near-sterile: fine Akadama, fine Kanuma, and vermiculite in 1:1:1, sterilized with boiling water or a microwave pass. SANBI notes for the closely related crassicaule that "keeping the medium damp at 15–21°C suppresses damping-off."
Sowing method
Either no cover or a very thin dusting on a pre-moistened surface. Space seeds at least 1 cm apart to prevent crowding.
Light & temperature
Bright shade, 15–22°C. As a winter-grower, heating above 25°C actually suppresses germination. September through November is the right window in Japan; germination usually arrives in 1–4 weeks, and growers report sprouting in as little as a week under warm-room conditions.
Watering
Bottom-water 1–2 cm up the pot. Don't let things dry out for the first 2–3 weeks, then drop the level gradually. Avoid cold water; room-temperature is preferable.
Fertilizer
None right after germination. Once true leaves emerge, a heavily diluted liquid feed once or twice a month. Growth is slow — first-year seedlings reach only a few mm to ~1 cm; the swollen base takes years.
From Germination to Repotting
Germination through true leaves
Continue bottom watering, keep in bright shade.
Weaning off bottom watering
Phase out gradually over 1–2 months.
First repotting
In the second or third year, in autumn, into a shallow pot.
Common Pitfalls
Mold & damping-off
- Cause: excess moisture, contamination, poor airflow
- Prevention: sterilize the substrate, refresh the bottom-water, run a circulation fan
Etiolation
- Cause: insufficient light. The active winter season runs through low-sun months
- Prevention: run an LED close indoors, or move to bright shade outdoors on clear days
Seeds fail to germinate
- Cause: stale seed, temperatures too high
- Prevention: sow as soon as a batch arrives. Skip the heat mat — keep room temperature 15–22°C
Summer stall and rot
- Cause: heat and humidity during summer dormancy, or watering in summer. The single biggest risk for this species
- Prevention: taper water from May–June and go fully dry before the rainy season; through summer hold under shade with airflow in the coolest spot, with an air-conditioned room as a legitimate option
Notes
Not CITES-listed, but assessed Near Threatened in Namibia in habitat; choose seed-grown or nursery-propagated material.
