Showy, colorful flower spikes make gladiolus a favorite for generations of gardeners. Gladiolus, also called sword lilies, are sun-loving plants that can grow 2-5 ft. tall. Their flower spikes add wonderful color to the mid to late summer garden and are a favorite for cut-flower displays. Gladiolus bulbs can also be grown in containers. Grown from corms, gladiolus are planted in the spring, after the last spring frost, and usually bloom about 3 months after planting. They grow best in well-drained soil. Gladiolus are not winter hardy, and in zones 3-7, must be lifted in the fall or grown as annuals. When considering gladiolus for sale online, take into account their height and flower color.