Mammillaria magnimamma
| Light | Bright light to full sun; a few hours of direct sun brings out the best form |
|---|---|
| Water | Regularly in the growing season once the mix has dried; keep dry and cool in winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; hardy to roughly USDA zones 9b–11 |
| Propagation | Seed and offsets (see Propagation — seed, Propagation — offsets) |
| Toxicity | Non-toxic to cats and dogs |
Mammillaria magnimamma is a hardy, highly variable clustering cactus from the highlands of central Mexico, and one of the most familiar members of the huge genus Mammillaria. It is easily recognised by its large, angular, cone-shaped tubercles and the generous white wool that gathers in the axils between them, from which its cream to pink flowers emerge in a neat ring around the crown. Because it varies so much from plant to plant, it has collected a long list of synonyms and is often sold under the common name Mexican pincushion.
Description
Mammillaria magnimamma begins as a solitary flattened globe and, with age, offsets freely from the base to build up broad, mounding clumps of many heads. Individual stems are usually 5–13 cm across, grey-green to deep green, with a slightly sunken growing point. The species takes its name (magni-mamma, "large teat") from its prominent, sharply four-angled tubercles, which are firm, pyramidal and arranged in spirals. The tubercles exude a milky latex when cut.
Spination is one of the most variable features in the whole genus: plants may carry anywhere from two to six stiff spines, straight or curved, short or strikingly long, and coloured from pale horn to nearly black. The axils between the tubercles are filled with dense white wool, most conspicuous around the crown. Small flowers appear there in spring, forming a tidy circlet; they range from creamy white and yellowish to pink and pale magenta, often with a darker midstripe. Flowering is followed by slender pink to red club-shaped fruits.
Distribution and habitat
The species is widespread across the central Mexican plateau, particularly in the states of Hidalgo, Querétaro, México, Guanajuato and neighbouring areas. It grows on rocky volcanic slopes, in grassland and among scrub, frequently in exposed, high-altitude sites. This montane origin makes it more tolerant of cold, bright conditions than many lowland cacti. It is common in the wild and not considered threatened, though — like the whole cactus family — it is listed under CITES Appendix II.
Cultivation
Mammillaria magnimamma is one of the easiest and most forgiving cacti to grow, which makes it an excellent choice for beginners. Give it a gritty, free-draining mix and the brightest position you can offer — plenty of direct sun encourages compact growth, strong spination and good flowering. Water regularly through the warm months once the soil has dried out, then keep the plant dry and cool over winter. A cold, dry winter rest not only prevents rot but is the key to a generous spring display of flowers.
The species is remarkably tolerant of cold when kept dry, shrugging off light frost in a protected spot, though it is safest to keep it above freezing. Its main enemy is standing moisture: an open mineral mix and a snug pot go a long way. See Watering and Repotting for general technique.
Propagation
Because the plant clusters so readily, the simplest method is to remove an offset, let the cut surface callus for a few days, and pot it into a dry gritty mix; see Propagation — offsets and Propagation — cuttings. The species also sets seed freely and comes readily from a warm, humid sowing, though seedlings show the same wide variation as wild plants — part of the fun of raising it from seed. See Propagation — seed for a full walkthrough.
Common problems
- Rot — the usual cause of loss, almost always from overwatering, a slow-draining mix, or moisture sitting in the crown over winter.
- Etiolation — too little light stretches the body and weakens the tubercles and spines, spoiling the tight symmetry.
- Pests — mealybugs love to hide in the woolly axils, and root mealybugs and red spider mites can also appear; inspect the crown and roots regularly (see Pests and diseases).
See also
- Mammillaria — the genus overview
- Soil and potting mix · Watering · Propagation — offsets · Propagation — seed · Repotting · Pests and diseases