Leave gladiolus in the ground?

We planted gladiolus in the ground and in containers this summer. I’ve heard they need to be dug up and stored over the winter. Really?

Gladiolus are tender summer-flowering plants that grow from corms, and where you live will probably determine whether to dig them up or not. Here in Middle Tennessee (Zone 7a), the recommendation from the University of Tennessee Extension is to dig up and dry the corms after the foliage dies back and before a heavy frost, but the truth is, most gardeners I talk to here leave the corms in the ground and they usually survive.

In colder areas, they should be dug and stored. The Web site of the Purdue University Cooperative Extension Service (in Indiana) for example, says that gladiolus corms should be dug after frost. Dig the corms by loosening the soil so that you can pull the plant out of the ground. Shake off the loose soil and allow the corms to dry in the sun for a day or two. Cut the foliage off 1 – 2 inches above the corms and store them in a cool, dry place.

Plant the corms again after the soil has warmed up, in late April or May. By planting in two-week intervals between May and July, you can have a succession of blooms for several weeks beginning about mid-summer.