Turbinicarpus horripilus
| Light | Bright light with a little shade from the harshest afternoon sun |
|---|---|
| Water | Sparingly; let the mix dry out completely between waterings, kept dry in winter |
| Soil | Very free-draining, mostly mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; a cool, dry winter rest is beneficial |
| Propagation | Seed (primary); offsets from clustering plants |
| Toxicity | Non-toxic to cats and dogs |
Turbinicarpus horripilus is a small, clumping cactus from the limestone canyons of Hidalgo in central Mexico. It forms short-cylindrical, dark green to grey-green stems that offset freely into low clusters, each stem armed with stiff, dark-tipped spines and crowned in season with cheerful magenta to purplish-pink flowers. Like the rest of its genus it is a slow-growing miniature that rewards patience, and it was for many years placed in the segregate genus Gymnocactus.
Description
Turbinicarpus horripilus grows as a short-cylindrical body that in time clusters into a low mound of many heads. Individual stems are firm and rather columnar for the genus, dark green to a dull grey-green, and patterned with spiralling tubercles rather than continuous ribs. Each areole carries a set of stiff, straight spines that are noticeably darker toward their tips, giving the plant a bristly, well-armed look that sets it apart from the softer-spined members of the genus.
Flowers open from near the growing tip, funnel-shaped and magenta to purplish-pink with a paler edge, appearing over the warmer months. As with most Turbinicarpus the blooms are large in proportion to the modest body, a big part of the appeal for collectors.
Distribution and habitat
The species is native to the state of Hidalgo in central Mexico, where it grows on steep limestone canyon walls and rocky outcrops. Plants root into cracks and pockets of gritty, alkaline substrate, often wedged among rock where drainage is sharp and competing vegetation is sparse. This cliff-dwelling habit is reflected in cultivation, where the plant strongly resents anything holding moisture around its roots.
Unlike most cacti, which fall under CITES Appendix II, the whole genus Turbinicarpus is listed under the stricter Appendix I, and several species are of serious conservation concern in habitat, their wild populations depleted by illegal collecting. Nursery-propagated plants are widely available and legal to own and trade; collecting from the wild is not.
Cultivation
T. horripilus is grown much as the rest of the genus. Give it a very free-draining, mostly mineral mix with plenty of grit, ideally with some limestone or crushed rock to suit its alkaline origins, in a pot that is not too generous. Site it in bright light with just a little protection from the fiercest afternoon sun, which keeps the body compact and the spination strong.
Water thoroughly only once the mix has dried out completely, then wait; through winter keep the plant cool and entirely dry, which both prevents rot and helps trigger the following season's flowers. Overwatering and a slow-draining mix are the two things most likely to kill a plant, so err toward keeping it lean. See Watering and Repotting for general technique.
Propagation
Seed is the standard and most reliable method, sown on a warm, gritty surface kept humid until the tiny seedlings appear; growth is slow but steady. Because the species clusters, established clumps can also be increased by removing rooted offsets, allowing the cut surfaces to callus, and potting them into the same mineral mix. See Propagation — seed and Propagation — offsets for full walkthroughs.
Common problems
- Rot — almost always from overwatering or a mix that stays wet; stems soften and discolour from the base.
- Etiolation — too little light makes stems stretch, pale, and lose their tight, bristly form.
- Pests — mealybugs (white fluff among the tubercles and roots) and red spider mites (fine webbing, bronzed skin) are the usual offenders. See Pests and diseases.
See also
- Turbinicarpus — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — seed · Propagation — offsets