A sign of the holidays is the amaryllis bulb for sale in retail stores. Bold and beautiful, the huge, showy flowers of hybrid amaryllis (Hippeastrum) raise spirits during the cold, gray days of winter. These large, tender bulbs produce spectacular flowers that can be up to 6 inches across in colors of reds, oranges, pinks, white, yellows, and bicolor on thick stalks that can rise 24 inches high.