(This plant comes in a 3.5 inch 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).
Description: It is a solitary plant that produces profuse yellow flowers. This cactus is indeed beautiful even without its blooms.
Flower: Yellow to golden-yellow.
Blooming season: Late winter to spring.
Cultivation and propagation: These mountainous plants have thick taproots and are susceptible to overwatering. They love a very permeable, coarse mineral soil as well as to be strictly kept dry throughout the winter period since it is very sensitive to any moisture excesses. To prevent rottenness, it is also advisable to surround its root neck by very rough sand or grit, this helps a fast water drainage. They require also an appropriate air circulation and are sometime grafted to avoid root problems. They need to be kept in a cool place during winter rest (at 0-10°C). This is important for the flowers, as well as for their health. Without this cool winter period, they normally won't get any buds.
Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz