Commonly called Amaryllus, this is a large bulb grown indoors in cold climates (13-15C), usually for flowering around Christmastime.
Plant in bulb compost in a heavy pot, with one-third of the bulb showing above th surface. Place in a warm, bright spot. Once the leaves appear water sparingly and feed with a house-plant fertiliser twice a month. After the flowering period, let the leaves die back naturally, stop water and feed and leave dormant for 3-4 months. In late Autumn remove bulb from pot and loosen the roots, replant in new potting compost. The growing process then starts anew.