Mammillaria bombycina
| Light | Bright light with some direct sun; a few hours of morning sun suits it well |
|---|---|
| Water | Sparingly; let the mix dry fully between waterings, and keep dry through winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; roughly USDA zones 9b–11 |
| Propagation | Offsets (primary); also seed |
| Toxicity | Non-toxic to cats and dogs |
Mammillaria bombycina is a clustering pincushion cactus from north-central Mexico, prized for the dense, silky white wool that fills the spaces between its tubercles. Each areole carries a spreading crown of fine white radial spines together with a few stouter central spines, the lowest of these longer, reddish-brown and hooked, and in spring a ring of small purplish-pink flowers opens around the top of each head — earning it the common name silken pincushion. It is one of the more forgiving members of Mammillaria, and a long-time favourite with collectors.
Description
Mammillaria bombycina begins as a solitary cylindrical to club-shaped stem and, with age, clusters freely to form mounded colonies of many heads. Individual stems reach roughly 10–20 cm tall and up to about 6 cm across, firm and deep green beneath their spination. The body is built from spirally arranged conical tubercles, and the axils between them are filled with the copious white wool that gives the species its silky look.
Each areole bears numerous short, white radial spines that lie against the body like a fine comb, together with a small number of stouter central spines. The lowest central is typically longer, reddish-brown to amber, and distinctly hooked — a feature that readily catches on clothing and skin, so handle the plant with care.
Flowers appear in spring, forming a neat ring near the crown of each mature head. They are small and funnel-shaped, purplish-pink to deep pink, and are sometimes followed by slender pinkish seed pods.
Distribution and habitat
The species is native to north-central Mexico, in the states of Aguascalientes and Jalisco and neighbouring areas, where it grows on rocky slopes and in crevices in a semi-arid climate. As with many Mexican cacti, its habitat is patchy and localised, and — like the whole cactus family — it is listed under CITES Appendix II. Nursery-propagated plants are widespread, affordable and entirely legal to own and trade; collecting from the wild is not.
Cultivation
Mammillaria bombycina is an easygoing cactus and a good choice for a keen beginner, provided it is not overwatered. Grow it in a gritty, mostly mineral mix in a pot that drains freely, and give it bright light with a few hours of direct sun to keep the spination tight and encourage flowering. Water thoroughly once the mix has dried out, then allow it to dry again before the next drink.
Through winter, keep the plant cool and completely dry; this rest both prevents rot and helps trigger the spring ring of flowers. See Watering and Repotting for general technique. As the plant clusters it will eventually appreciate moving up a pot size, but it flowers well even when a little crowded.
Propagation
The easiest method is by offsets: mature clumps produce plenty of heads, which can be gently detached, left to callus for a few days, and then set on a barely moist gritty mix to root. See Propagation — offsets and Propagation — cuttings for details.
The species can also be raised from seed, which germinates readily on a warm, mineral surface kept humid; seedlings are slow at first but undemanding. Because clusters offset so freely, most growers simply divide established plants.
Common problems
- Rot — the usual cause of loss, almost always from overwatering, a poorly draining mix, or moisture during the cold winter rest; heads soften and discolour from the base.
- Etiolation — too little light makes the stems stretch pale and lose their compact, well-spined form.
- Pests — mealybugs (white fluff, often hidden in the woolly axils) and red spider mites (fine webbing and bronzed skin) are the most common; the dense wool can make mealybugs hard to spot early. See Pests and diseases.
See also
- Mammillaria — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — offsets · Pests and diseases