Copiapoa laui
| Light | Bright light; a little shade from the harshest midday sun |
|---|---|
| Water | Very sparingly; allow to dry completely between waterings, dry rest in winter |
| Soil | Extremely free-draining, mostly mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing, ideally above about 5 °C; roughly USDA zones 10a–11 |
| Propagation | Offsets and division; seed |
| Toxicity | Non-toxic to cats and dogs |
Copiapoa laui is one of the very smallest members of the genus Copiapoa, a Chilean cactus that forms dense, low clusters of tiny brownish heads studded with minute spines. Each head is only a centimetre or so across, so a mature clump reads as a tight little cushion of jewel-like buttons — a firm favourite among growers of miniature and slow-growing cacti.
Description
Copiapoa laui is a dwarf, clustering cactus whose individual heads rarely exceed 1–2 cm in diameter. The stems are dull greyish-green to brownish, often flushed darker in strong light, and carry small, low tubercles rather than pronounced ribs. The spines are tiny, fine and closely appressed to the body, giving the plant a soft, almost combed appearance rather than a fierce one.
In habit the plant hugs the ground, with a substantial tuberous root anchoring it below the surface — much of the plant's bulk is underground, and only the flattened tops of the heads sit above the soil. Small flowers open from the woolly crown, yellow and modest in size, followed by little fruits. Like many Copiapoa, it grows extremely slowly, and a broad clump represents many years of patient cultivation.
Distribution and habitat
The species is native to the Atacama coastal desert of northern Chile, one of the driest regions on Earth. There it grows in gritty, mineral ground where the plants draw much of their moisture from coastal fog (camanchaca) drifting in from the Pacific rather than from rainfall, which may be absent for years at a time. Contracting down into the substrate is a survival strategy against relentless sun and drought.
Because of their restricted range and the pressures of over-collection and habitat disturbance, wild Copiapoa populations are of conservation concern; like the whole family they are listed under CITES. Nursery-propagated plants are the responsible and legal way to grow the species — wild-collected material should be avoided.
Cultivation
Copiapoa laui is prized but demands restraint, especially with water. Grow it in a very open, almost entirely mineral mix in a pot deep enough to accommodate the tuberous root, and give it bright light — good light keeps the heads compact and brings out the brownish colouring, while too little causes soft, pale, etiolated growth. A little shade from the fiercest afternoon sun in a hot greenhouse does no harm.
Water sparingly and only when the mix has dried out completely, easing off further in the heat of high summer when the plant may rest, and keeping it essentially dry and cool through winter. Overwatering and a slow-draining mix are the fastest routes to rot in this species. Because it is so slow, some collectors grow it grafted (see Grafting) to build up size more quickly, though many prefer the tighter, more characterful growth of plants on their own roots. See Watering and Repotting for general technique.
Propagation
The clustering habit makes vegetative propagation straightforward: established clumps can be divided, or individual offsets removed, allowed to callus, and rooted on a barely-moist mineral surface — see Propagation — offsets and Propagation — cuttings. The species can also be raised from seed, though seedlings are tiny and grow with the same glacial patience as the adults.
Common problems
- Rot — nearly always from overwatering, a stale mix, or moisture sitting around the neck and tuberous root; the heads soften and discolour.
- Etiolation — too little light makes the heads swell, pale and lose their tight, brownish character.
- Pests — mealybugs (white fluff between the heads and at the roots) and red spider mites are the usual offenders; inspect the crowded crowns regularly. See Pests and diseases.
See also
- Copiapoa — the genus overview
- Grafting · Soil and potting mix · Watering · Propagation — offsets · Propagation — seed