Plant in spring when the soil is warm and after all frost danger is past. Choose a site with full sun and adequate drainage, and protected from strong winds which could knock down the tall flower spikes. Use a garden fork or tiller to work the planting bed to a depth of 12 to 15 inches. Mix in a 2- to 4-inch layer of compost to assure proper drainage. Use a bulb planter to make a hole about 5-6 inches deep. Add fertilizer to the bottom of the hole and scratch it into the surface of the soil. Set the corm in the hole with the pointed end up. Fill in soil to cover and press down firmly. Space 4 to 6 inches apart, then water thoroughly. If you are planting tall varieties, install stakes at planting time, taking care not to damage corms. Stagger plantings to extend the blooming season. To retain moisture and help control weeds, apply a 2- to 4-inch layer of mulch around the plants.
Keep the soil evenly moist throughout the growing season. One rule of thumb is that you should water if it does not rain at least one inch in a week.
Plants will bloom more freely if you remove spent flowers from the plants, and cut down the stalks as the final flowers fade.
Mulch beds with a layer of straw in zones 7 and 8. In colder zones, you should dig up the corms before freezing temperatures arrive. Cut the stalks to one inch, and let them cure for 1 to 2 weeks in a warm, airy location. Then separate the oldest bottom corms and discard them. Store the newer, large corms in mesh bags in a well-ventilated room, at temperatures of 35°-45° F. Replant corms in spring when frost danger has passed.