(This plant comes in a 3.5" pot. You will receive a very similar plant to the one in the picture. It may or may not be blooming at the time of your purchase. The plant is shipped in its pot to prevent any damage to the roots).
This plant is easy to grow. With age, it will form large clumps. The name longimamma comes from the Latin for "long nipple".
Recommended temperature zone: USDA: 9-11
Frost tolerance: Hardy to 22°F (-5°C)
Minimum avg. temperature: 50°F (10°C)
Sun exposure: Light shade to shade
Origin: USA (Texas), Mexico (Hidalgo, Querétaro)
Watering needs: Regular water in spring and summer. Keep dry in winter.
Propagation: Seeds, offsets, tubercles
Blooming habits: The Mammillaria longimamma produces an abundance of bright yellow flowers, 2.5" in diameter (6 cm), in summer.
Propagation: Tubercles can be removed from the plant, let to dry a day or two, and planted.
Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz