This fat guy, Gymnocalycium horstii, can’t wait until April so it can get a new pot. It has clumped to the point there is no room left to grow in its original nursery container. Clumping usually doesn’t occur when the cactus is young, so this one is probably four years old based on its size. It is one of the larger Gymnos; eventually it will reach about eight to 10 inches in diameter.
I’ve always liked this genus of cactus. It is easy to identify because of the little indentations or ‘chins’ under the areoles, (not so evident on this species) as well as the naked calyx, or the outer covering of the flower bud. The genus name is from the Greek language meaning naked calyx, or a bud that is free of spines or hairs. Gymnos have prolific flowering habits, and this species usually blooms from late spring until fall. The flowers of this species are a pale pink.
Gymnocalycium is sun sensitive, especially in the Phoenix area. Full sun will easily scorch and burn the exposed skin, as will extreme cold. I keep all seven of my Gymno species on the patio in a bright spot, because in order for them to bloom they need bright light. The G. horstii is a summer grower and needs regular watering, but in winter, lay off the water.
If you look closely at the skin of this G. horstii, you can see small light dots on the skin, probably caused by an extra cold night. They may or may not go away. These small defects won't hurt the cactus, but they may disqualify it from winning a ribbon in a cactus show.