Astrophytum myriostigma is probably the most popular species of astrophytum. Its completely distinct look, as the name indicates, resembles a bishop’s hat. Although with age it takes on a more columnar appearance, reaching 2′ in height and 8″ in diameter. Like asterias, it is spineless, another feature which sets it apart from other cacti. These seeds will produce ornamental plants with thick, green bodies that are heavily speckled with white. The root of the name astrophytum refers to the stars, as in the word “astronomy,” which reflects a somewhat star-shaped appearance that is characteristic of cacti in this genus. Astrophytum myriostigma is typically found at high altitudes in central and northern Mexico.
We offer several variants of this species. The “columnare” variety has a taller, more columnar stem. The ‘nudum” variety is characterized by a pure green stem. “Tricostatum” is extremely rare and has only three ribs instead of five. Similarly, “Quadricostatum” has only four ribs. “Onzuka” is a coveted and eye-catching Japanese cultivar.
Astrophytum myriostigma is cold hardy to about 20 degrees Fahrenheit. For best results it should be given light shade, although it will tolerate full sun. During the summer it should be given moderate water and fertilizer, but it should be kept dry starting in October. An alkaline, porous soil will provide necessary drainage, and watering from below potted cacti so the water wicks up through the soil is recommended. Grafting will also help by lifting the cactus out of the soil where it may come into contact with standing water. Grafting on to faster-growing root stocks such as pereskiopsis, San Pedro and blue myrtle will also speed up growth.
Growing Information: https://www.worldseedsupply.com/germination-of-cacti-such-as-san-pedro-cactus-peruvian-torch-and-other-spiny-friends/