Escobaria vivipara
| Light | Bright light to full sun |
|---|---|
| Water | Water thoroughly when in growth, letting the mix dry out between waterings; keep bone-dry through a cold winter rest |
| Soil | Very gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Exceptionally cold-hardy; survives hard frost when kept dry (roughly USDA zones 4–10 depending on provenance) |
| Propagation | Seed; division of established clumps |
| Toxicity | Non-toxic to cats and dogs |
Escobaria vivipara is a small, exceptionally cold-hardy North American cactus that forms low spiny clusters and rings itself with bright magenta flowers in early summer. One of the most widely distributed cacti on the continent, it ranges from northern Mexico across the western United States and Great Plains all the way into the Canadian prairies. It is commonly sold under the names spinystar and beehive cactus. It belongs to the genus Escobaria, and has long been shuffled between that genus and Coryphantha.
Description
Escobaria vivipara is a small globular to shortly cylindrical cactus, usually only a few centimetres across, that is solitary when young but tends to offset with age into tight clusters or low mounds. Instead of true ribs the body is built from spirally arranged tubercles — small nipple-like projections — each tipped with an areole bearing a dense, star-like spread of spines. The radial spines are numerous, thin and pale, often white to greyish, and overlaid with a few stouter, darker central spines, giving the plant a bristly, snowflake-patterned look from above.
Flowers appear at or near the crown in late spring and early summer. They are showy for such a small plant, typically bright magenta to rose-pink with narrow, pointed petals and prominent stamens, opening in sunshine over a period of days. These are followed by greenish fleshy fruits. The plant's wide range means appearance varies considerably from place to place, and several regional forms and varieties have been named over the years.
Distribution and habitat
Few cacti are as widespread. E. vivipara occurs from the deserts and grasslands of northern Mexico north through the Great Plains and Rocky Mountain states, reaching into the Canadian prairie provinces — one of the northernmost distributions of any cactus. It grows in open, sunny, well-drained sites: short-grass prairie, gravelly slopes, rocky outcrops and sandy flats, often tucked among grasses and low shrubs.
Across this range it endures brutal winters, long droughts and baking summers. Its cold tolerance comes in part from a habit of dehydrating and shrinking down into the soil as temperatures fall, riding out hard freezes in a partly dried, contracted state.
Cultivation
Escobaria vivipara is prized by growers of hardy cacti because, given the right conditions, it can be grown outdoors year-round in climates far too cold for most cacti. The single non-negotiable requirement is drainage: plant it in a very gritty, mostly mineral mix and, if growing it in the ground, in a raised or sloping bed where water never lingers.
Give it as much sun as you can. Water regularly through the warm growing season once the soil has dried, then withhold water completely as autumn cools — a plant that goes into winter dry and firm will shrug off frost that would rot a wet one. Cold-hardiness is closely tied to this dry winter rest, so a rain cover or an unheated, bright overwintering spot helps in wet-winter climates. In containers, choose a snug pot and repot infrequently (see Repotting and Watering).
Propagation
Seed is the usual and most reliable method, and one that preserves the variation across the species' range; sow onto a warm, gritty surface kept lightly humid until germination (see Propagation — seed). Older plants that have clustered can also be divided, lifting and separating rooted heads from the clump; let any cut or torn surfaces callus before potting the divisions up dry. See Propagation — offsets for general technique.
Common problems
- Rot — by far the most common cause of loss, almost always from a wet winter or a slow-draining mix; the base or individual heads soften and discolour.
- Etiolation — too little light makes the body soft and elongated and reduces flowering.
- Pests — mealybugs (white fluff among the tubercles and roots) and red spider mites are the usual offenders; watch the root zone as well as the body.
See also
- Escobaria — the genus overview
- Soil and potting mix · Watering · Propagation — seed · Propagation — offsets · Repotting · Pests and diseases