Gladiolus grow from an enlargened bulb-like underground stem called a corm. Corms are planted each spring and dug in the fall. Each summer the old "mother corm" shrivels and dries up soon after the leaves emerge from the ground. One or more new corms are then produced during the growing season. These new corms are dug in the fall and stored over winter.
The quality of gladiolus flowers depends on the quality of the corms. Buy corms from a reputable local source to obtain the highest quality. If the corms must be shipped to you, open the packages as soon as they arrive. Store the corms until planting time in a cool, dry, well-ventilated place safe from freezing.
When choosing corms, judge quality more by corm depth rather than width. Corms with high centers and plump shape are better than large, flat, thin ones. The thicker the corm, the higher quality bloom you can expect.