Gladiolus are magnificent, tall flowers that are show-stopping in the garden and in the house. Tall-stemmed gladiolus easily last a week in a vase, so their value as cut flowers makes them even more popular. Gladiolus bulbs are technically not bulbs---they are swollen root stems called corms. These corms can be dug, dried, and stored until the next planting season.
Wait six weeks after flower production before digging up the gladiolus corms. The only exception to the six-week rule, according to "The Reader's Digest All-New Illustrated Guide to Gardening," is in the case of frost. If frost occurs, go ahead and dig up the corms.
Prior to digging up the gladiolus corms, mark a circle with a spade or shovel all the way around the gladiolus plant, leaving a few inches between the circle and the base of the plant. Dig out the circle, working carefully to avoid slicing the gladiolus with the shovel blade.
Cut off the stems and dispose of them. Gently shake any excess dirt off the corms.
Dry the corms. If it is warm and sunny outdoors, the "Guide to Gardening" suggests spreading the corms outside and covering them with a waterproof cover at night. If it is wet or cool outside, however, dry them indoors by spreading the corms out on trays in a single layer.
Remove the old, shriveled corm and its roots from the new corm after two to three weeks of drying time. It should not be difficult to remove the old corm; if it is, wait another week and try again. Dispose of the old corms and roots.
Put the dried corms in a container that allows for air circulation, such as a mesh bag or a crate with space between the slats. Keep the corms at a cool but not freezing temperature.