The hedgehog cactus is a small, cylindrical cactus with pronounced spiny ribs, native to the deserts of the Southwest and Mexico. Some stay solitary little columns; others gradually pup into tight clusters. Given a good sunny life, mature plants can reward you with bright spring flowers.

Set it in a south-facing window with plenty of direct sun, in a fast-draining cactus mix, and water only when the soil has dried completely, easing off further in winter. Overwatering is the one common mistake. It can summer outdoors in a dry, bright spot, then come in before frost.