Most barrel cacti are of the genus Ferocactus. Ferocactus, meaning "fierce or wild cactus". They are always cylindrical or barrel shaped and are usually among the largest cacti of the North American deserts. There about 35 species of Ferocactus. These are slow-growing plants, reaching ages of 100 years or more. They grow to at least 30 cm tall at maturity, but usually reach a height of 1 metre or even 3 metres. They are excellent for growing in containers on patios and in greenhouses or as landscape plants. They are grown for their brightly coloured, often hooked, and somewhat dramatic spines. In some species, one or more central spines are curved like a fishhook, accounting for the common name Fishhook Barrel Cactus. When young, they are usually globular shaped, though they eventually become columnar with age. Barrel Cactus flowers always grow at the top of the plant. They bear no spines and only a few scales. The majority of Ferocactus species flower in summer and are pollinated by bees. Fruits become fleshy and often juicy when mature, but are not usually considered edible. Hardiness zone 10-11, (1øC/35øF, 4øC/40øF). They require a minimum temperature of 40§ F. Many of these plants can survive hot sun and frost. Most species grow best in a fairly roomy, well-drained container filled with a porous compost that doesn't contain too much humus. Place them in a spot where they'll receive sun and do not water until the soil becomes fairly dry. After a while the soil can be moistened regularly but never kept constantly saturated.