Melocactus azureus

Melocactus or Melon Cactus comes from Mexico and Brazil, and there are about 40 species in this genus. This is a finicky genus. Everything needs to be just right--sun exposure, temperature, watering, soil composition, and drainage. Other cacti are more forgiving regarding their care. This genus takes a little more effort. The cactus pictured is M. azureus. This species has a blue-green body, hence the species name.

Melocactus waits until the body finishes growing before it forms a woolly top, or cephalium. Bristles and small red flowers appear from this cephalium, and the cephalium can keep growing for years. Sometimes it will grow taller than the body of the cactus. The average body can grow to about eight inches tall, but I've seen larger ones at cactus shows. Once it forms a cephalium, it should not be repotted. This is a young specimen, so I have quite a few years left to decide what kind of permanent pot it’s going to get. In the meantime, I’ll repot to a larger container every couple of years.

Unlike most cacti, Melocactus needs regular water, even in winter, and should never be allowed to completely dry out. It needs good drainage, and some sources say to use only distilled water. I use filtered water, and so far, so good. Instead of humus rich potting soil, pure quartz gravel can be used instead of soil, but that's not something you can easily find at the local nursery. When the cephalium begins to grow, it resembles a cap, so this cactus genus is also called the Turk’s Cap Cactus.