Turbinicarpus schmiedickeanus
| Light | Bright light with some shade from the harshest afternoon sun |
|---|---|
| Water | Very sparingly; allow to dry fully between waterings, keep dry in winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; roughly USDA zones 9b–11 with a cool, dry winter rest |
| Propagation | Seed (primary); grafting to speed slow seedlings |
| Toxicity | Non-toxic to cats and dogs |
Turbinicarpus schmiedickeanus is a highly variable miniature cactus from arid limestone country in northeastern Mexico, and one of the most collected members of the small-growing genus Turbinicarpus. It is best understood as a complex of named subspecies — including klinkerianus, macrochele, schwarzii, flaviflorus, dickisoniae, andersonii and rioverdensis — which differ noticeably in body shape, spination and flower colour while sharing the same tiny, tuberous-rooted growth habit.
Description
Turbinicarpus schmiedickeanus is a small, mostly solitary cactus, typically only a few centimetres across, with a soft greyish-green to bluish body that sits atop a stout, carrot-like taproot. The body is divided into low tubercles rather than continuous ribs, each tipped with an areole bearing a small number of spines. Spination is the most obvious point of variation across the complex: some forms carry curved, papery, cork-like central spines that twist over the crown, while others are shorter and stiffer or nearly inconspicuous.
Flowers appear from the woolly crown, opening mainly in late winter and spring. Depending on the subspecies they range from white and pale pink to magenta or clear yellow (as in subsp. flaviflorus), and are large and showy relative to the diminutive plant that produces them.
Because the plant is so small and cryptically coloured, in habitat it often sits nearly flush with the surrounding rock and gravel, contracting into its taproot during drought and becoming very hard to spot.
Distribution and habitat
The species is endemic to Mexico, where its various subspecies occupy scattered, often highly localised sites across the states of San Luis Potosí, Nuevo León, Tamaulipas and neighbouring areas. Plants grow on limestone — in rock crevices, gravelly flats and exposed slopes — usually wedged among stones with only the top of the body visible.
Many populations are naturally tiny and restricted to a single hill or valley, which makes the complex both taxonomically interesting and conservation-sensitive. Wild plants are threatened by illegal collection and habitat disturbance. The entire genus Turbinicarpus is listed on CITES Appendix I — the strictest category, barring commercial trade in wild-collected plants. Nursery-propagated, seed-grown plants are widely available and are the only responsible source — collecting from habitat is illegal and damaging.
Cultivation
Turbinicarpus schmiedickeanus is a rewarding but water-sensitive miniature that punishes a heavy hand. The single greatest risk is rot at the neck where the body meets the taproot, so grow it in a very free-draining, mostly mineral mix with generous grit, in a deep enough pot to accommodate the root. Give it bright light — which keeps the body compact and encourages flowering — with a little shade from the fiercest summer sun.
Water thoroughly only when the mix has dried right through, and reduce watering sharply as autumn approaches. A cool, completely dry winter rest is important: it prevents rot and sets up the following season's flowers. See Watering and Repotting for general technique, and take particular care not to bury the neck when potting.
Propagation
Seed is the standard and most satisfying method. The seeds are tiny but germinate readily when sown on a warm, mineral surface kept humid, and raising the different subspecies from seed is a popular way to appreciate the variation within the complex. See Propagation — seed for a full walkthrough.
The species rarely offsets, so vegetative propagation is uncommon. Where offsets or heads are available they can be removed and rooted (see Propagation — offsets), and growers sometimes graft slow seedlings onto a vigorous rootstock to speed them along before returning them to their own roots.
Common problems
- Rot — overwhelmingly the main killer, usually from overwatering, a slow-draining mix, or moisture sitting at the neck; the plant softens and discolours from the base.
- Etiolation — too little light makes the body elongate and lose its tight, tubercled form.
- Pests — root mealybugs on the taproot are a particular nuisance in a mineral mix, along with spider mites and ordinary mealybugs in the crown. See Pests and diseases.
See also
- Turbinicarpus — the genus overview
- Grafting · Soil and potting mix · Watering · Propagation — seed · Repotting