Cleistocactus samaipatanus
| Light | Bright light to full sun; tolerates a little shade |
|---|---|
| Water | Regular in the growing season, letting the mix dry between waterings; keep dry and cool in winter |
| Soil | Fast-draining but not lean; a gritty mineral mix with some organic matter (see Soil and potting mix) |
| Temperature | Keep above freezing; roughly USDA zones 9b–11 |
| Propagation | Cuttings (easy), offsets, and seed |
| Toxicity | Non-toxic to cats and dogs |
Cleistocactus samaipatanus is a clustering, slender-stemmed cactus from the valleys of Bolivia, grown above all for its lavish display of bright scarlet, tubular flowers. Formerly placed in the genera Borzicactus and Bolivicereus, it is a vigorous, free-flowering member of Cleistocactus that rewards the grower with vivid colour over a long season. It is sometimes offered under its older names Borzicactus samaipatanus and Bolivicereus samaipatanus.
Description
Cleistocactus samaipatanus produces upright to leaning, cylindrical stems that branch and cluster freely from the base, forming a many-stemmed clump in time. The stems are relatively slender — a few centimetres thick — and clothed in numerous low ribs bearing closely set areoles. Fine, bristly, pale golden spines line the green stems in clusters, never dense enough to obscure the body.
The flowers are the plant's chief glory. Unlike the narrow, near-closed "cleisto" blooms of many relatives, those of C. samaipatanus open into a distinctly flared, bright scarlet to crimson tube, borne along the sides of the stems. They appear over a long spring-to-summer season and are attractive to hummingbirds in habitat. Ripe fruits are small and rounded.
Distribution and habitat
The species is native to Bolivia, where it grows on slopes and among rocks in the seasonally dry inter-Andean valleys, the region around Samaipata giving it its name. In these habitats it experiences warm growing conditions with summer rain and a distinctly drier, cooler resting period, a rhythm worth remembering in cultivation.
Cultivation
This is one of the more forgiving and rewarding columnar cacti for the hobbyist. Grow C. samaipatanus in a fast-draining mix that nonetheless holds a little organic matter, as the species is a comparatively thirsty grower during the warm months. Give it bright light to full sun for the strongest growth and best flowering, and water regularly once the mix has dried, easing off sharply as temperatures fall.
Through winter keep the plant dry and cool but frost-free; this rest both prevents rot and helps set the following season's abundant flowers. Feed lightly during active growth, and see Watering and Repotting for general technique. Older clumps can become top-heavy, so a slightly weightier or wider pot helps keep them stable.
Propagation
Because the species clusters so readily, vegetative propagation is easy. Detach an offset or take a stem cutting, let the cut surface callus for several days in a dry, shaded spot, then pot into a barely moist gritty mix until roots form. Rooted cuttings quickly resume the parent's clumping habit. The species also grows readily from seed sown warm on a mineral surface, though seedlings take longer to reach flowering size. See also Propagation — offsets.
Common problems
- Rot — the usual cause of loss, from a waterlogged mix or watering while cold; stems soften and discolour from the base.
- Etiolation — too little light produces thin, pale, drawn-out growth with weaker flowering.
- Pests — mealybugs (white fluff tucked among the spines and at the roots) and red spider mites (fine webbing and a bronzed sheen) are the most common; see Pests and diseases.
See also
- Cleistocactus — the genus overview
- Soil and potting mix · Watering · Propagation — cuttings · Propagation — offsets · Repotting