Astrophytum ornatum is endemic in Mexico (from the Guanajuato state to the Hidalgo state), growig in canyons and limestone cliffs.
Astrophytum ornatum is a solitary cactus: it grows a globose to shortly columnar stem up to 120 cm high, with a star-shaped cross-section. Stem is dark-green to green-grey-coloured, and it presents white or yellowish cross bands of wooly scales; the pattern that these form is quite variable for their density and distribution. Ribs are usually 8 (but can be 5 to 10), prominent, often spiralling. This Astrophytum is quite more thorny than the others, presenting 5-11 amber radial spines and a larger central spines for areole. Flower is apical, large, lemon-yellow coloured.
Astrophytum ornatum is a slow, summer-growin cactus. It needs a well-draining, sandy-gritty substratum. It needs a big amount of sunlight and grows at its best in full sun, but can tolerate light shade. Water it weekly during summer and keep it perfectly dry during winter, to avoid frost damages (it is theoretically hardy to -10°C, but to grow a healthy plant, it should not be exposed to temperatures below 5°C); it does not tolerate high atmospheric humidity, and a good ventilation is great to prevent it.
Propagation can easily be done by seeds. During spring, put them in containers with fine, well-draining sandy soil. Seeds can be sown in pots of fine, well-drained sandy soil: cover them with a fine layer of grit and water with fungicide. For the first two weeks keep the humidity level high covering the pots with a sheet of glass; replace it with light shade-cloth, and for the next two weeks mist once or twice a day. Then, mistings can be done every two and every three days. In the end, rooted seedlings can be planted separaterly in small containers.
This Astrophytum is the one with the southern habitat of the genus.