Green Industry Resources
Hort Update- Seasonal Information for the Green Industry
Fall Care of Gladiolas
Gladiolas are an easy and very showy flower to add to the garden.They also make excellent cut flowers with a long vase-life. However, gladiola corms are not winter hardy in Nebraska and must be dug each fall.
The corms are ready for digging about six weeks after they have bloomed. By this time the foliage should be yellowing and dying back. However, if the tops are still healthy leave the corms in the ground until the foliage begins to die back, or until just before a hard freeze. This give the plants the longest time possible for the corms to grow and increase in size, resulting in bigger flower stalks the following year. If the foliage does begin to die back dig the corms as soon as possible to prevent disease problems while the corms are in the ground.
Dig the corms when the soil is dry. This will make digging and cleaning of the corms much easier. Carefully lift the corms with a spade or spading fork, avoiding injury to the corms as much as possible. If the tiny cormels are desired for future propagation, dig carefully and sort them immediately by variety. Shake off soil and cut the tops off just above the corms.
Place the corms in a light, warm, well-ventilated place for several weeks to cure. Corms are cured to eliminate excess moisture in the corm and husks as rapidly as possible. This helps prevent storage problems.
After the corms are cured, separate each new corm from its old dried corm. These two parts should snap apart easily by hand and leave a clean scar on underside of the new corm. Remove the loose husks, leaving the wrapper husks intact. Also remove the small cormels and place them in a labeled paper bag for winter storage. Before putting the corms and cormels into storage, dust them with an insecticide for thrip control. Be sure to discard all damaged or diseased corms.
Place the corms in trays, paper bags, mesh onion bags, or even nylon stockings for winter storage, making sure that all corms are clearly labeled. Keep the varieties separated since they multiply at different rates. Light colors such as white, pink, and yellow are usually more vigorous and may multiply faster than darker colors. If the corms are mixed it may seem the lighter colors are taking over. Store gladiola corms in a dark, cool, dry, well-ventilated location during the winter. Ideal storage temperatures are 35 to 45°F.