Echinopsis mamillosa
| Light | Bright light with some protection from the harshest afternoon sun |
|---|---|
| Water | Regularly in the growing season once the mix has dried; keep dry and cool in winter |
| Soil | Fast-draining mineral-rich mix (see Soil and potting mix) |
| Temperature | Keep above freezing; roughly USDA zones 9–11 |
| Propagation | Seed; offsets where produced |
| Toxicity | Non-toxic to cats and dogs |
Echinopsis mamillosa is a solitary, ribbed globular cactus from the highlands of southern Bolivia and neighbouring northwest Argentina, valued by growers for its neat, orderly symmetry and its large, showy flowers. Its tidy geometry and reliable summer flowering make it a favourite among collectors of Echinopsis.
Description
Echinopsis mamillosa forms a rounded to shortly cylindrical green body, usually growing as a single head rather than clustering. The plant is divided into numerous straight, well-defined ribs, notched into low rounded tubercles that give the species its name. Along the ribs sit evenly spaced areoles bearing short, stiff radial spines and one or a few slightly longer central spines, typically yellowish with brownish tips and pressed close to the body.
The flowers are the plant's chief attraction: large and funnel-shaped, borne on a long tube that emerges from areoles low on the sides of the body. In the typical form they are white flushed with rose, but colour forms range through pink to a deep carmine-red — the deep red-flowered plants are sometimes distinguished under the name Echinopsis kermesina — and they open at night, each bloom lasting only about a day, through the warmer months.
Distribution and habitat
The species is native to the mountains of southern Bolivia and adjoining northwest Argentina, where it grows on rocky slopes and in gritty, well-drained ground at moderate to high elevation. In habitat it experiences strong sunlight, sharp drainage, warm growing-season rains and a cool, dry winter — conditions that are the key to growing it well in cultivation.
Cultivation
Echinopsis mamillosa is an accommodating plant that rewards a little seasonal discipline. Grow it in a free-draining, mostly mineral mix in bright light, giving a little shade from the most intense afternoon sun to keep the body from scorching. During the warm months water thoroughly whenever the mix has dried out; the species is thirstier in growth than many desert cacti, but standing wet is still the main cause of loss.
As autumn approaches, taper the watering and keep the plant dry and cool through winter. This dry rest both prevents rot and sets the flower buds, so a cold, dry winter is well worth arranging for the sake of the spring and summer display. See Watering and Repotting for general technique.
Propagation
The species is readily raised from seed, which germinates freely on a warm, gritty surface kept humid until the seedlings are established. Where a plant produces offsets these can be removed and rooted as offsets; allow the cut surface to callus before potting into a dry, gritty mix. Because many plants stay solitary, seed remains the most dependable route to new plants.
Common problems
- Rot — from overwatering, a poorly draining mix, or watering during the cold winter rest; the body softens and discolours, usually from the base.
- Failure to flower — most often the result of too warm or too wet a winter; a genuine cool, dry dormancy is what triggers budding.
- Etiolation — too little light makes the body pale and stretch, spoiling the compact symmetry that is the species' charm.
- Pests — mealybugs (white fluff in the areoles and around the roots) and red spider mites (fine webbing and a bronzed skin) are the usual offenders. See Pests and diseases.
See also
- Echinopsis — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — seed · Propagation — offsets