Sclerocactus spinosior
| Light | Full sun; bright, airy conditions all year |
|---|---|
| Water | Very sparingly in the growing season; keep bone-dry through a cold winter rest |
| Soil | Extremely gritty, lean mineral mix with sharp drainage (see Soil and potting mix) |
| Temperature | Cold-hardy when dry; tolerates hard frost, roughly USDA zones 5–9 |
| Propagation | Seed |
| Toxicity | Not known to be toxic to cats or dogs |
Sclerocactus spinosior is a small, barrel-shaped Great Basin fishhook cactus native to the cold deserts of the Great Basin in Utah and eastern Nevada, notable for its dense armour of stiff spines — some of them prominently hooked — and its pink to magenta-purple spring flowers. Like the rest of the genus it is a plant of harsh, cold high-desert habitats, and it is prized by collectors as much for its fierce spination as for its bloom. It belongs to Sclerocactus, the group commonly known as the fishhook cacti.
Description
Sclerocactus spinosior forms a solitary, more or less globular to short-cylindrical stem, usually reaching around 8–15 cm tall and somewhat less across, occasionally larger with age. The body is divided into a number of tuberculate ribs bearing closely set areoles, so that a well-grown plant can be almost hidden beneath its own spines.
The spination is the plant's defining feature. Each areole carries numerous straight, spreading radial spines and several stouter central spines; one or more of the centrals are typically flattened and strongly hooked, giving the genus its "fishhook" name. Spine colour varies from whitish and pale grey to reddish-brown, and the interlaced spines of neighbouring areoles knit together into a dense protective cage.
Flowers open near the top of the plant in spring, funnel-shaped and roughly 3–5 cm across, in bright shades of pink, rose and magenta-purple. They are followed by small, dryish fruits that split to release the seed.
Distribution and habitat
The species is native to the Great Basin, centred on western and central Utah and extending into eastern Nevada, where it grows in cold high desert — sagebrush flats, gravelly benches and open, stony ground on well-drained substrates. These are habitats of hot dry summers and genuinely cold, sometimes snowy winters, and the plant is adapted to a long, dry, freezing dormancy.
As with all cacti, Sclerocactus is listed under CITES, and members of this genus are of conservation concern in the wild. Wild collection is both harmful and, in most cases, illegal; nursery- and seed-grown plants are the only responsible source. Always buy propagated stock rather than plants dug from habitat.
Cultivation
Sclerocactus spinosior has a reputation as a challenging plant, and the reasons are worth understanding. It resents root disturbance and, above all, dislikes moisture around its roots while dormant. Grow it in full sun in an exceptionally gritty, lean, almost purely mineral mix, ideally in a deep pot to accommodate its taproot, and give it maximum ventilation.
Water carefully during the active growing periods of spring and autumn, always letting the mix dry out completely in between, and then keep the plant absolutely dry through winter. Given a cold, dry rest the species is remarkably frost-hardy, but the same plant kept cold and wet will rot quickly — cold plus damp is the classic killer of this genus. Many growers succeed by keeping it in an unheated but rain-sheltered frame or greenhouse. See Watering and Repotting for general technique, and note that repotting is best done cautiously while the plant is dry.
Some growers side-step the touchy roots by grafting seedlings onto a hardy rootstock, which produces faster, easier growth at the cost of the plant's natural, compact habit.
Propagation
Seed is the standard and usually the only method, as the species is almost always solitary and does not offset. Fresh seed can be slow and erratic to germinate; a period of cold, moist stratification often improves results, mimicking the winter the seed would experience in habitat. Sow onto a gritty, mineral surface and be patient with seedlings, which are slow-growing but rewarding. See Propagation — seed for a full walkthrough.
Common problems
- Root and basal rot — by far the main cause of loss, from watering while dormant, a mix that holds moisture, or cold wet conditions in winter. Keep it lean, gritty and dry when at rest.
- Loss after repotting — the sensitive taproot resents disturbance; repot only when necessary, when dry, and withhold water until new root activity resumes.
- Etiolation — too little light produces soft, pale, elongated growth and poor spination; this is a full-sun plant.
- Pests — mealybugs (including root mealybugs) and red spider mites can take hold, especially under glass; inspect the crown and roots periodically. See Pests and diseases.
See also
- Sclerocactus — the genus overview
- Grafting · Soil and potting mix · Watering · Repotting · Propagation — seed · Pests and diseases