Echinocereus dasyacanthus
| Light | Bright light to full sun; enjoys strong direct sun |
|---|---|
| Water | Sparingly; let the soil dry completely between waterings, kept dry in winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Very hardy; tolerates hard frost when kept dry |
| Propagation | Seed (primary); occasional offsets |
| Toxicity | Non-toxic to cats and dogs |
Echinocereus dasyacanthus is the Texas rainbow cactus, a cylindrical-to-barrel species of the American Southwest whose spines are laid down in alternating bands of colour that ring the stem like a rainbow. It is admired for producing some of the largest, most brilliant flowers in the genus Echinocereus — broad, silky blooms usually in shades of yellow.
Description
Echinocereus dasyacanthus forms a solitary or few-branched, cylindrical to shortly barrel-shaped stem, typically reaching 15–30 cm tall and 5–10 cm across, though old plants may cluster modestly. The stem carries numerous low ribs closely packed with areoles, and the dense, comb-like (pectinate) spines almost obscure the green body. It is these spines that give the plant its common name: as the stem grows, flushes of pale, pink, reddish and brownish spines are produced in sequence, banding the column with soft horizontal stripes of colour.
The flowers are the species' great glory. Opening from near the stem tip in spring, they are large — often 8–12 cm across — funnel-shaped and satiny, most commonly a clear bright yellow, sometimes flushed with orange, pink or magenta tones. Each bloom lasts several days and opens widest in warm sun. The fruit that follows is fleshy, spiny and greenish, ripening as the spines shed.
Distribution and habitat
The Texas rainbow cactus grows in the Chihuahuan Desert region of the American Southwest and adjacent Mexico, with a stronghold in western Texas, southern New Mexico and northern Chihuahua. It favours open, sunny desert flats, rocky limestone slopes and gravelly grassland, rooting in thin, sharply drained mineral soils among sparse desert scrub. In habitat it endures a punishing range of conditions — intense summer heat and dry, frosty winters — which accounts for the toughness it shows in cultivation.
The species has been treated at times as a variety of Echinocereus pectinatus (as E. pectinatus var. dasyacanthus), and the two are closely related and easily confused where their ranges overlap.
Cultivation
Echinocereus dasyacanthus is one of the more forgiving and rewarding rainbow cacti to grow, prized for combining showy spination with spectacular flowers. Give it as much sun as you can — strong light brings out the best spine colour and encourages flowering — and a very free-draining, mostly mineral mix in a pot that dries quickly. Water generously during the warm growing season once the soil has dried out, then reduce sharply.
For flowers, a cool, completely dry winter rest is important; it also lets the plant show its full cold-hardiness. Kept dry, established plants tolerate hard frost, and many growers overwinter them in an unheated but protected space. Wet cold, on the other hand, is fatal — winter damp is the usual cause of loss. See Watering and Repotting for general technique.
Propagation
Seed is the standard and most reliable method. The seeds germinate well on a warm, gritty surface kept lightly humid, and seed-raised plants grow into good, well-spined specimens. Where a plant offsets, the pups can be removed once rooted or callused and grown on, though clustering is modest in this species; see Propagation — offsets and Propagation — seed for details.
Common problems
- Rot — almost always from winter wet or a slow-draining mix; the stem softens and discolours from the base.
- Poor colour and no flowers — usually too little light; weak sun mutes the spine banding and suppresses blooming.
- Etiolation — insufficient light also makes the stem stretch thin and pale, losing its stocky form.
- Pests — red spider mites (fine webbing, bronzed skin) and mealybugs (white fluff among the spines and roots) are the usual culprits; see Pests and diseases.
See also
- Echinocereus — the genus overview
- Echinocereus pectinatus — the closely related, sometimes-confused species
- Soil and potting mix · Watering · Propagation — seed · Propagation — offsets