It takes a lot of work to harvest gladiolus corms in the fall. You're going to have to go out there and dig up all of your glads right after the first frost of the year kills the foliage back. Then you must clean them off, sort and categorize, cure, sort again and label, treat for bugs, and finally get them packed away for the winter. The lazy person may very well choose to skip this chore and bypass a lot of dirty work. Frugal gardeners opt to save lots of money the following spring by getting their gladiolus corms up out of the ground before freezing inflicts damage. The bonus for those willing to work is lots of new underground offspring.
Harvest your gladiolus corms in the fall, right after the first frost in your area. Dig carefully around each plant -- about 4 to 6 inches away from the stalk -- to avoid damaging any of the corms.
Shake the excess soil off the corms. Use a clean, sharp knife to cut the foliage off where it meets the corm. Label some cardboard boxes and sort the corms into them immediately. It's easier than you think to quickly forget which corms are which variety.
Store the corms on some old newspapers spread out in a warm, dry spot with excellent ventilation for about three weeks. Leave plenty of space between them to promote air circulation and do not allow them to freeze. This is known as "curing" the harvested corms.
Inspect the corms carefully after they've cured. Discard any that are damaged, diseased or rotting. The original corms that you planted will be shriveled and smaller than you remember. Each of those has produced a large, healthy new one on top of the old mother corm.
Break the old bulb off by hand and discard it. Pull off any husks that are loose but leave the wrappers on the corms. Pick off the tiny bulbs, or cormels, that have grown around the base of the large, fresh one. Put large corms and cormels into separate paper bags if you plan set them out in different locations next year. Remember that it will take new cormels another two or three years to bloom. Label all of your bags.
Put 50 corms in a paper bag and add 1 tsp. of powdered Sevin (carbaryl). Close the bag and shake it. This will help protect against thrips, which like to over-winter on gladiolus corms in storage. If you don't like using chemicals, soak the corms in hot water at about 160 degrees F for two or three minutes. Don't allow them to boil. Air dry soaked corms on old newspapers overnight.
Store your harvested gladiolus corms in the legs of old nylon pantyhose in a cool, dry, dark spot with good ventilation. The ideal temperature range is between 35 and 45 F. Don't allow them to freeze.