Mammillaria backebergiana
| Light | Bright light to a few hours of direct sun; some shade from the fiercest afternoon sun |
|---|---|
| Water | Regularly in the growing season once the soil dries; keep dry and cool in winter |
| Soil | Fast-draining, gritty mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; roughly USDA zones 9b–11 |
| Propagation | Seed; occasionally offsets where clustering |
| Toxicity | Non-toxic to cats and dogs |
Mammillaria backebergiana is a cylindrical, deep-green Mammillaria from central Mexico, prized for its neat habit, short manageable spines and the ring of bright magenta flowers that crowns the plant in spring and early summer. It is an easy, free-flowering species that rewards beginners and seasoned collectors alike, and it commemorates the cactus botanist Curt Backeberg in its name.
Description
Mammillaria backebergiana forms an erect, columnar body that is usually solitary when young and may cluster with age, offsetting from the base. The stem is firm and glossy dark green, built from conical tubercles arranged in neat spirals; the axils are nearly naked, carrying only a little wool and sometimes a few bristles, and the tubercles exude a milky latex when cut. Each areole carries around ten short, stiff radial spines and one to three straight central spines, yellowish with darker tips, giving the plant an open, tidy look rather than a dense woolly one.
The flowers are the main attraction: deep magenta to purplish-pink, funnel-shaped and modest in size, they open in a distinct ring around the top of the stem. As with most in the genus, a successful flowering ring is often followed by slender club-shaped fruits carrying the tiny seeds.
Distribution and habitat
The species is native to central Mexico — recorded from the states of México, Guerrero and Michoacán, within the drainage of the Río Balsas — where it grows on cliffs and rocky slopes, rooting in crevices among other drought-adapted vegetation at roughly 1,400–1,900 m elevation. In habitat it experiences a warm growing season with summer rains and a cooler, drier rest, and typically roots in thin, sharply drained mineral soils with good exposure to light.
Cultivation
Mammillaria backebergiana is one of the more forgiving columnar mammillarias and a good choice for a beginner. Grow it in a very free-draining, mostly mineral mix in a pot that drains freely, and give it bright light with a little protection from the most intense afternoon sun to keep the body a healthy green and encourage flowering.
Water thoroughly through the warm months once the soil has dried, then let it dry again before the next watering; taper off in autumn and keep the plant dry and cool over winter, which both prevents rot and sets up the spring flush of flowers. See Watering and Repotting for general technique. Feed lightly during active growth with a low-nitrogen cactus feed.
Propagation
Seed is the standard and most reliable method: sow the fine seed on a warm, moist mineral surface and keep it humid until the seedlings establish (see Propagation — seed). Where a plant has clustered, rooted offsets can be removed and grown on; allow the cut surface to callus before potting, as described in Propagation — offsets.
Common problems
- Rot — the usual cause of loss, almost always from overwatering or a slow-draining mix, especially in cold weather; the stem softens and discolours from the base.
- Etiolation — too little light makes the body stretch, pale and lose its compact form.
- Pests — red spider mites (fine webbing and bronzed skin) and mealybugs (white fluff among the tubercles and roots) are the most common; see Pests and diseases.
See also
- Mammillaria — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — seed · Propagation — offsets