Gardeners who live outside gladioli hardiness zones can save the bulbs or corms from one growing season to the next by protecting them during the winter. The advantage is that you will save money because you will not have to purchase new gladiolus corms. Good preparation is the key to keeping your glads happy over the winter. You will also have to be willing to go out and dig the bulbs from the garden after the outdoor weather has turned cold.
Dig your gladiolus bulbs out of the ground soon after the first frost in the fall and before their leaves turn brown completely. Exercise caution while digging near your gladiolus to avoid nicking, cutting or impaling the corm.
Loosen the soil around the corm. Grasp the stem and pull gently straight up and out of the ground. Shake and brush the corm with your hand to remove excess dirt. Inspect the hole and surrounding area and collect any cormels, small subsidiary corms. Place the cormels in a paper bag for future planting.
Label and segregate your corms according to variety so that you will know when your gladioli will bloom in the summer.
Cure the corms by placing them in a room with good air circulation. Maintain a room temperature of between 70 and 80 degrees Fahrenheit for two to four weeks.
Inspect the corms for dryness. Examine the new corms that the original corms you planted produced during the growing season. Identify the old corms by their dry and shriveled look and feel. Snap or pull apart the loose, old corms from the new corms. Discard the old corms.
Cure the new corms to heal the scar you created when you separated the new from the old. Inspect the corms and discard any damaged ones.
Dust the corms with carbaryl, a pesticide that helps to reduce thrip activity.
Place the corms in a room where the temperature is between 40 and 50 degrees Fahrenheit. Choose among several methods to store the corms over the winter, including putting the corms in open, paper bags; hanging them in panty hose; laying them flat in cardboard boxes; or laying them on mesh screens.
Inspect corms periodically during the winter and check for overall condition and for the presence of thrips that can survive in any stage on stored corms. Identify young thrips by their light buff color and small size, measuring roughly 1/32 inch. Identify adult thrips by their black bodies, white belts and 1/16-inch size. Apply insecticide or introduce lady bugs to control the insects.