Lobivia arachnacantha
| Light | Bright light with some direct sun; a few hours of morning sun brings the best flowering |
|---|---|
| Water | Regularly in the growing season, letting the mix dry between waterings; keep dry and cool in winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; a cool, dry winter rest encourages buds |
| Propagation | Offsets (readily); also seed |
| Toxicity | Non-toxic to cats and dogs |
Lobivia arachnacantha is a small, freely clustering cactus from Bolivia, prized by growers for the huge, brilliantly coloured flowers it produces on such a modest little body. Its name comes from the Greek for "spider spine", a reference to the fine, spreading spines that press flat against the stem like the legs of a spider, and its blooms open in shades of yellow, orange and red that can be as wide as the plant is tall. Like most of its relatives it is now often treated botanically as a species of Echinopsis, but it remains widely known and traded under the traditional genus name.
Description
Lobivia arachnacantha forms low, offsetting clumps of small globular to shortly cylindrical stems, each only a few centimetres across. The stems are ribbed and set with small areoles carrying short, thin, spreading spines that lie close against the body — the "spidery" character that gives the species its name. Spine colour ranges from pale straw to brownish, and individual clones vary considerably.
The flowers are the plant's great attraction: broadly funnel-shaped and remarkably large in proportion to the stem, they open in vivid yellow, orange or red, often with a contrasting throat. As with many Lobivia, each bloom lasts only a day or two, but a well-grown clump in spring and early summer can throw a succession of them over several weeks.
Distribution and habitat
The species is native to Bolivia and, marginally, adjacent northern Argentina (Salta), where it grows on stony montane hills and rocky slopes at roughly 1,800–2,600 m. Plants of this habit typically nestle among rocks and low vegetation that give a little shade and shelter, rooting in gritty, sharply drained ground that dries quickly after the summer rains and stays cold and dry through winter. This natural rhythm of a warm wet season and a cool dry rest is the key to growing and flowering the plant well.
Cultivation
Lobivia arachnacantha is an easygoing, rewarding cactus and a good choice for the beginner who wants big flowers without a big plant. Grow it in a gritty, mostly mineral mix in a pot that drains freely, in bright light with a few hours of direct sun to keep the growth compact and the flowering generous.
Water regularly through spring and summer, always letting the mix dry out between waterings, then taper off in autumn. The most important thing you can do to guarantee flowers is to give the plant a cool, completely dry winter rest — this triggers the buds. Because it clusters happily, it is well suited to a shallow pan where a colony can spread. See Watering and Repotting for general technique.
Propagation
The simplest method is by offsets: mature clumps produce plenty of pups that can be detached, left to callus for a few days, and potted into the same gritty mix, where they root quickly. See Propagation — offsets. The species also comes readily from seed, sown warm on a mineral surface and kept humid until germination; seed-raised plants introduce useful variation in spine and flower colour. See Propagation — seed and Propagation — cuttings for related methods.
Common problems
- Rot — the usual cause of loss, almost always from a mix that holds too much moisture or from watering during the cold winter rest; the affected stems soften and discolour.
- Shy flowering — a plant kept too warm, too wet or too shaded in winter often refuses to bloom; give it a genuinely cool, dry dormancy.
- Etiolation — too little light draws the stems up thin and pale and spoils the neat clustering habit.
- Pests — mealybugs (white fluff in the areoles and among the offsets) and red spider mites are the most likely visitors; see Pests and diseases.
See also
- Lobivia — the genus overview
- Echinopsis — the genus into which this species is now often placed
- Soil and potting mix · Watering · Propagation — offsets · Propagation — seed · Repotting