Quick facts and care essentials
• Zones 4-9, 12-24, 29-33
• Full sun
• Regular watering during growth and bloom
These long-time favorites have sword-shaped leaves and flaring funnel-shaped flowers borne in slender spikes. The large summer-flowering garden kinds (grandiflora hybrids) grow 3 to 6 feet tall and come in a wide variety of colors.
Plant corms in spring after soil has warmed; they'll bloom in 65 to 100 days. If you plant corms at 1- to 2-week intervals over a period of 4 to 6 weeks, you can enjoy an extended flowering season. Set each corm about 4 times deeper than it is thick; space 4 to 6 inches apart.
In the zones listed, corms can overwinter in the ground, though many gardeners prefer to dig them. In colder regions, they must be dug and stored in a frost-free location. Dig after the leaves turn yellow; cut off and discard tops.
Arrange corms in a single layer in a dry, dark area and let dry for 2 to 3 weeks. Pull off and discard old corms and roots. Store new corms over winter in onion sacks or nylon stockings hung in a cool, well-ventilated area.