Copiapoa dealbata
| Light | Very bright light to full sun; acclimatise to avoid scorch |
|---|---|
| Water | Very sparingly; long dry rests, especially in winter |
| Soil | Gritty, sharply draining mineral mix (see Soil and potting mix) |
| Temperature | Keep frost-free; USDA zones 9b–11 |
| Propagation | Seed (primary); offsets from established clumps |
| Toxicity | Non-toxic to cats and dogs |
Copiapoa dealbata is a large, slow-growing, clumping cactus from the coastal deserts of northern Chile, celebrated for the impressive white-grey mounds of many heads it forms with age. Its chalky, ash-coloured skin — the source of the epithet dealbata, "whitewashed" — is coated in a fine waxy bloom that reflects the harsh coastal sun, making a mature clump one of the most striking sights among the copiapoas. It is sometimes treated as a variety of the closely related Copiapoa cinerea.
Description
Copiapoa dealbata begins as a solitary globular stem but, over many years, branches freely from the base to build broad clumps that can eventually hold dozens of heads and spread well over a metre across in habitat. Individual stems are cylindrical to shortly columnar, reaching perhaps 6–16 cm in diameter, and are clothed in the pale chalky-white to grey epidermis that gives the species its name.
The ribs are prominent and carry closely set areoles bearing stiff, needle-like spines that range from pale amber to dark grey or almost black, contrasting sharply against the ghostly body. A patch of felty wool sits at the crown, from which the flowers emerge. Blooms are funnel-shaped and yellow, opening in the sunniest part of the day, and are followed by small fruits.
Distribution and habitat
The species is endemic to a limited stretch of the Atacama coast in the Chilean region of Atacama, growing on arid hillsides and coastal terraces within reach of the sea. Rainfall there is almost nonexistent; the plants survive largely on the frequent coastal fog (the camanchaca) that rolls in off the Pacific, condensing on their waxy skins. The reflective white bloom helps them endure fierce sun and drought in one of the driest environments on Earth.
Like all cacti, Copiapoa dealbata is listed under CITES Appendix II, and wild populations are vulnerable to illegal collection and habitat disturbance. Nursery-grown, seed-raised plants are the responsible source for collectors; plants should never be taken from habitat.
Cultivation
Copiapoa dealbata rewards patience above all else — it is naturally very slow, and forcing growth spoils both its form and its characteristic colouring. Grow it in a very gritty, mostly mineral mix in a pot that drains freely, and give it the brightest position you can offer; strong light is what encourages the dense spination and the pale, waxy skin. Acclimatise plants gradually to avoid scorching the bloom.
Water is the main hazard. This is a fog-desert plant that resents sitting wet, so water sparingly only when the mix has dried right out, and keep it almost completely dry through the cool, dark months. Good airflow and a cool, dry winter rest reduce the risk of rot and encourage flowering. See Watering and Repotting for general technique.
Propagation
Seed is the usual and most rewarding method, though seedlings are slow and demand careful, mineral-based, well-ventilated conditions. Because the species clumps with age, established plants can also be increased by removing rooted or semi-rooted offsets from the base; let the cut surfaces callus thoroughly before setting them on a dry, gritty mix. See Propagation — seed and Propagation — offsets for full walkthroughs.
Common problems
- Rot — the commonest cause of loss, almost always from overwatering, a poorly draining mix, or moisture during the winter rest.
- Loss of bloom — the waxy white coating can rub off or fail to develop under weak light or from frequent handling; it does not regrow on old skin.
- Etiolation — too little light produces soft, greener, elongated growth that never recovers its natural squat, chalky form.
- Pests — mealybugs (including root mealybugs) and red spider mites are the usual offenders. See Pests and diseases.
See also
- Copiapoa — the genus overview
- Copiapoa cinerea — the closely related species this taxon is sometimes placed under
- Soil and potting mix · Watering · Propagation — seed · Propagation — offsets