Mammillaria spinosissima (Red-Headed Irishman)

Scientific Name

Mammillaria spinosissima Lem.

Common Names

Red-headed Irishman, Irish Red-head

Synonyms

Mammillaria spinosissima subsp. spinosissima, Mammillaria auricoma, Mammillaria pitcayensis, Mammillaria pilcayensis, Mammillaria centraliplumosa, Mammillaria haasii, Mammillaria gasterantha, Mammillaria crassior, Mammillaria virginis

Scientific Classification

Family: Cactaceae
Subfamily: Cactoideae
Tribe: Cacteae
Subtribe: Cactinae
Genus: Mammillaria

Description

Mammillaria spinosissima is a cactus with cylindrical, dark blue-green stem, up to 12 inches (30 cm) tall and up to 4 inches (10 cm) in diameter, almost hidden under a dense covering of spines. The flowers are fairly freely produced in spring and form a ring of purplish or deep-pink blooms round the upper part of the plant.. They are up to 0.8 inch (2 cm) long and up to 0.6 inch (1.5 cm) in diameter.

Photo via wikimedia.org

Hardiness

USDA hardiness zones 9a to 11b: from 20 °F (−6.7 °C) to 50 °F (+10 °C).

How to Grow and Care

To encourage better flowering, allow the plants to enjoy a cooling period in the winter and suspend watering. Unlike many other cacti, which use their ribs as storage devices, Mammillaria feature raised tubercles, from which spines emerge. When you water, the tubercles will expand to allow for increased water storage. The flowers emerge from the axils of these tubercles on the previous year's growth, which accounts for their interesting halo effect. It's imperative that the cactus is not exposed to prolonged dampness and sitting water. Never let your cactus sit in a dish of water. Lastly, make sure to fertilize during the growing season for the best results.

Repot as needed, preferably during the warm season. To repot Mammillaria, make sure the soil is dry before repotting, then gently remove the pot. Knock away the old soil from the roots, making sure to remove any rotted or dead roots in the process. Treat any cuts with a fungicide. Place the plant in its new pot and backfill with potting soil, spreading the roots out as you repot. Leave the plant dry for a week or so, then begin to water lightly to reduce the risk of root rot… – See more at: How to Grow and Care for Mammillaria