Mammillaria bombycina - Silken pincushion cactus

Mammillaria bombycina is an indoor cactus prized for its round silhouette adorned with white bristles and its pink crown of flowers. This small Mexican species can be placed on a windowsill, where it will enjoy abundant light. Its cushion-shaped growth naturally fits into a display of succulent plants.

This species belongs to the Cactaceae family. It is native to Mexico, more precisely from south-western Aguascalientes and north-eastern Jalisco, where it grows in dry environments, on rocky terrain, within xeric scrub and open formations. Described in 1910 by Quehl, it is now recognised as a full species.
This plant is solitary when young, then produces offshoots and forms a dense clump with age. Its growth is slow to moderate. In a pot, it reaches 10 to 20 cm in height, each stem measuring 5 to 6 cm in diameter. The stems start globose, then become more cylindrical, and are covered with a bright green to medium green skin. They bear regularly arranged conical tubercles whose hollows are filled with silky white down. There are 30 to 40 radial prickles on the areoles; they are fine, white and shiny, arranged like a comb. In the centre, there are 2 to 4 stronger, reddish-brown to amber thorns, often hooked. It is this mix of white wool and curved thorns that gives this cactus its distinctive texture. In spring, sometimes until early summer, small funnel-shaped flowers about 1.5 cm in diameter appear, in deep pink to carmine pink, marked with a darker central line. In the wild, this species produces elongated, whitish to pale pink fruits, containing very small black seeds.

Indoors, Mammillaria bombycina requires very bright light, even morning sun, a dry atmosphere, around 30 to 50% humidity, and temperatures of 18 to 27 °C during the growing period. Keeping it between 8 and 12 °C in winter will promote flowering. It is an easy-to-grow plant but copes poorly with overwatering, lack of light and stuffy conditions. It will thrive placed in a conservatory, near a south- or west-facing window, or in a very bright office.

Mammillaria greatly benefits from staying outdoors from spring to autumn, exposed to the sun and sheltered from excessive rain. Bring it in before the first frosts to winter it in a bright, dry, cool, frost-free place.

To accompany it, consider for example Echeveria ‘Perle von Nürnberg’, Echeveria ‘Devotion’, Aeonium ‘Bronze Medal’ and Kalanchoe beharensis ‘Fang’, succulent plants that share its preference for light and dry conditions, while providing different sizes and textures.