Gladiolus flowers, also called gladiolas, are part of the iris (Iridaceae) family and were originally planted in Africa, Europe and the Mediterranean. Today, most are hybrids (crossings) of species from East Africa and South Africa. Species (original) gladiolas look simpler than the lush, ruffled hybrids popular in bouquets. The flower’s name is related to the Latin word “gladia” for sword and refers to the shape of gladiolus leaves.
Gladiolas are grown from bulb-like corms. They should be planted every two weeks during the growing season to maintain continuous blooms. The time for the first planting depends on where you live.
A good rule is to plant gladiolas after final frost around the time for planting tomatoes. In southern regions where there is little frost, some gardeners leave the corms in the ground year round or plant them as early as late January. But in places with cold winters, such as Colorado and Minnesota, mid-May is the date that agricultural extension offices suggest.
The University of Missouri says that gladiolas tolerate many soils, but prefer a slightly acidic pH of about 6.0 to 6.5. Corms should be watered immediately after planting. They need moist, well-drained soil, such as loam or sandy loam rich in organic matter. Plant them in full sun away from woody shrubs and trees. Avoid windy locations that might cause stems to snap.
Gladiolus corms are planted with the pointed end upward. As to how deep to plant them, Colorado State University says a general rule is to place corms at a depth two to three times their diameter. Use thin, tall sticks of lumber to stake gladiolas so they remain upright. Flower stalks can be tied to the stakes with soft twine or strips of at 10-inch intervals.