Espostoa nana
| Light | Bright light to full sun once established; acclimatise gradually to avoid scorch |
|---|---|
| Water | Moderate in the growing season, allowing the mix to dry between waterings; keep dry and cool in winter |
| Soil | Fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing and protect from frost; roughly USDA zones 10–11 |
| Propagation | Seed; occasionally cuttings or offsets |
| Toxicity | Non-toxic to cats and dogs |
Espostoa nana is a compact, slow-growing columnar cactus from the mountains of west-central Peru, cloaked so densely in fine white hair that the green body beneath is almost hidden. As one of the smaller and more manageable members of Espostoa — the group commonly called the Peruvian old man cacti — its modest size and soft woolly coat make it a favourite among collectors who want the classic hairy-column look without the eventual bulk of the larger, tree-like species. The name is often treated as a synonym of Espostoa melanostele subsp. nana, and the plant has also been placed in the segregate genus Pseudoespostoa.
Description
Espostoa nana forms a slender, upright column that stays comparatively short and narrow — reaching only roughly 0.9 m (about 3 ft) tall and some 8 cm across, and slow to do even that — branching from the base with age to build a small clump over many years. The entire stem is wrapped in long, silky white hairs that radiate from the areoles and largely obscure the ribs and spines below. Beneath this woolly cover the body carries numerous closely set ribs lined with fine pale spines, the longer of which push through the hair as short yellowish or amber points.
Like other members of the genus, mature plants develop a cephalium — a dense, wool- and bristle-filled zone along one side of the stem from which the flowers emerge. The blooms are nocturnal, opening pale and funnel-shaped, and are followed by small fleshy fruit. In cultivation flowering takes years to arrive, as the plant must reach a good size before the cephalium forms.
Distribution and habitat
The species is native to west-central Peru, in the Ancash region, where it grows on rocky slopes and in the dry inter-Andean valley of the Río Santa (the Callejón de Huaylas) at moderate to fairly high elevations, roughly 1,500–2,400 m. These habitats are bright and sharply drained, with warm days, cool nights and a pronounced dry season — conditions the dense hair helps the plant cope with by reflecting fierce sunlight and buffering temperature swings.
Cultivation
Espostoa nana is an undemanding grower by cactus standards, provided its roots are never left wet. Plant it in a very free-draining, mostly mineral mix and give it as much bright light as you can — strong light keeps the hair thick and white, whereas too little makes growth thin and the coat sparse. Acclimatise plants gradually to full sun, since the woolly surface can still scorch if moved abruptly.
Water moderately through the warm growing months, letting the mix dry out between drinks, then keep the plant dry and cool over winter to prevent rot and encourage healthy, compact growth. The white hair holds dust and moisture, so good air movement is helpful; avoid frequent overhead watering that leaves the wool sodden. See Watering and Repotting for general technique.
Propagation
Seed is the usual method and produces charming, already-hairy seedlings, though growth is slow. Where a plant has offset or branched, sections can be taken as cuttings and rooted after the cut surface has callused; basal offsets can likewise be removed and grown on (see Propagation — offsets). Vegetative propagation is less common simply because the species clumps slowly.
Common problems
- Rot — the main cause of loss, almost always from overwatering or a slow-draining mix; the base or a section of stem softens and discolours.
- Dirty or matted hair — the wool traps dust and can look grey; gentle handling and good light keep it looking its best, and it is best not to soak it repeatedly.
- Etiolation — too little light produces thin, pale growth with sparse hair, spoiling the characteristic look.
- Pests — mealybugs in particular hide readily within the wool and areoles, so inspect regularly; spider mites can also occur.
See also
- Espostoa — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — seed · Propagation — cuttings
- Pests and diseases