(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 good looking columnar cactus will grow about 5 to 7 inches a year. They are cold intolerant. Make sure they are not exposed to freezing temperatures. They need a well-drained soil mix. Water regularly in summer but allow to dry fully before watering again. During the winter months they should be rather kept dry. Since they are rapid growers, they need plenty of space for their roots. Repotting should be done every other year, or when the plant has outgrown its pot. Sun Exposure: Light shade when young, full sun later.
Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz