Astrophytum Coahuilense is easy to confuse with astrophytum myriostigma (Bishop’s Cap). However, the body of astrophytum coahuilense tends to have more gray flecks and has them consistently over the body of the plant. Astrophytum myriostigma can sometimes be more patchy with more green spots on the stem. The distinction between the two species becomes a bit more obvious when the plant is in bloom. Despite its similar appearance to myriostigma, astrophytum coahuilense is more closely related to astrophytum capricorne. Cross-pollination between astrophytum coahuilense and myriostigma will commonly result in sterile offspring. Astrophytum coahuilense has yellow flowers with red throats like those of astrophytum capricorne. In rare cases, you can find astrophytum coahuilense with pure red or pure yellow flowers. Astrophytum coahuilense fruits open up at the base rather than at the top, which is somewhat unusual. Most plants, including astrophytum myriostigma, open up from the tip. A single astrophytum fruit can contain up to 200 seeds.
We offer several varieties of astrophytum, including astrophytum asterias, capricorne and a number of myriostigma types. 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 coahuilense 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/
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