The genus Melocactus includes around 40 cacti from Mexico, the West Indies, and northern South America. Many of these species are endangered, and plants in cultivation are almost always grown from seeds. The botanical name comes from the Latine for "melon cacti". They are slow-growing.
Melocactus is as round as a ball with many strong, thorny ribs. When they are mature, the body stops growing and produces a crown on its apex named cephalium. This densely spined area is where the flowers and fruit will be produced. The cephalium can keep on growing for many years, and in some species can exceed the height of the body itself. Melocactus grows from April to October.
The Melocactus flowers are generally a shade of pink or red. They come in abondance from spring to fall depending on the species. They are followed by fleshy fruit. The plant is not mature enough to flower until it is 6 to 10 years old.
Hardiness zone 11, (4øC/40øF). Melocactus need a minimum temperature of 60§ F. Melocactus rests from October to April. During this time water sparingly. Keep the soil on the dry side, but make sure the roots never dry out. Do not feed in winter. Melocactus are tricky to grow, but given the proper care, will produce interesting and attractive specimens.
They have shallow, wide-spreading roots; therefore, grow them in pans or other wide, shallow containers. Melocactus needs a well drained, very light and porous soil. It needs plenty of light and more heat than other cacti. Water regularly, but allow the soil to dry quite a bit before watering again.