Cleistocactus baumannii
| Light | Bright light to full sun once established |
|---|---|
| Water | Moderate in the growing season; keep dry and cool in winter |
| Soil | Fast-draining mineral-rich mix (see Soil and potting mix) |
| Temperature | Best above freezing; will take a light, dry frost briefly (roughly USDA zones 9–11) |
| Propagation | Cuttings and seed |
| Toxicity | Non-toxic to cats and dogs |
Cleistocactus baumannii is a slender, freely branching columnar cactus from subtropical South America, best known for its slim green stems and its curious, tubular S-curved orange-red flowers that give it the common name scarlet bugler. A vigorous and forgiving grower, it is one of the more widely cultivated members of the genus Cleistocactus.
Description
Cleistocactus baumannii produces upright to sprawling stems only a few centimetres thick, which lengthen steadily and branch from the base to form a clustering, thicket-like plant. The stems are ribbed and closely covered in fine, bristly spines, ranging from pale gold to brown, that give the green body a soft, brushed appearance.
The flowers are the plant's signature feature. Like most of the genus they are cleistocactoid — long, narrow tubes that barely open at the mouth, so the bloom stays nearly closed even at its peak. In this species the tube is characteristically bent into an S-shape and coloured a warm orange to scarlet-red, with the stamens and style just protruding from the tip. Flowers are borne along the upper stems in the warmer months and, in habitat, are pollinated by hummingbirds drawn to the tubular red blooms.
Distribution and habitat
The species is native to subtropical South America, occurring across parts of Argentina, Paraguay, Uruguay and neighbouring Bolivia and Brazil. It grows in warm lowland scrub and open woodland, often scrambling among shrubs and rocks where its slim stems gain some support and dappled shade. Compared with high-Andean cacti it experiences a milder, more humid climate, which is reflected in its relatively generous appetite for water in cultivation.
Cultivation
Cleistocactus baumannii is an easy, fast-growing cactus and a good choice for beginners. Grow it in a free-draining but not impoverished mix and give it bright light or full sun to keep the stems sturdy and encourage flowering. During the growing season it appreciates more regular water than many desert cacti — water thoroughly, then let the mix approach dryness before watering again. Taper off in autumn and keep the plant dry and cool over winter, both to prevent rot and to promote next year's blooms.
The stems can become long and lax with age, so a roomy pot or a spot where they can lean and cluster suits the plant well. Feed lightly through the growing months and see Repotting for general technique as clumps fill their containers.
Propagation
The species is very easily propagated from cuttings: a length of stem cut cleanly, left to callus for several days, and set on the surface of a gritty mix will usually root without fuss. Basal branches can often be detached with roots already forming. Seed is also straightforward and germinates readily on a warm, humid mineral surface. See Propagation — cuttings and Propagation — seed for full walkthroughs.
Common problems
- Rot — the main risk, from a waterlogged mix or cold, wet winter conditions; stems soften and discolour from the base.
- Etiolation — too little light produces thin, pale, weak growth that reaches and flops rather than standing upright.
- Pests — mealybugs (white fluff among the spines and at stem joints) and red spider mites are the usual offenders; see Pests and diseases.
See also
- Cleistocactus — the genus overview
- Soil and potting mix · Watering · Propagation — cuttings · Propagation — seed · Repotting