Gladiolus is the largest genus in the Iridaceae family with 255 species. It has been studied by taxonomists and now includes Acidanthera, Homoglossum, Anomalesia, and Oenostachys along with species once included in Antholyza. The geographic range includes Africa, Madagascar, Europe, and the Middle East. Gladiolus has been a treasured flower in many areas of the world. Many of the fancy hybrids that are popular garden plants had their origins in some of the South African species. Telling apart the European species commonly grown is challenging for most of us. Information below from a number of our References attempts to include some of the distinguishing characteristics. Gladiolus plants are subjected to Thrips, especially the ones that grow and bloom in warm weather.
The standard reference book for the South African Gladiolus species is probably Goldblatt & Manning's hefty Gladiolus in Southern Africa. Another useful reference is Gladiolus in Tropical Africa.
Many of the winter-growing South African species have delicate-looking, multicolored flowers that bear little resemblance to the large, bold-colored summer-growing hybrids found in garden centers. But many of them are tough plants that can persist in the ground in a mediterranean-climate garden, and a few species (particularly Gladiolus tristis) will spread themselves around the garden by seed. These spreaders probably shouldn't be grown next to wild land in mediterranean climates.
Growing from seeds is not difficult for species in this genus. It is said that South African species require temperature under 20C to germinate successfully but Bill Richardson found that temperature fluctuation from -2C (28F) to nearly 20C (68F) during the day does not have a huge effect on germination. Since there are summer and winter growing species, one must choose the right time for planting. Winter growing species should be planted in the fall. Summer growing species should be sown in the spring, and require somewhat warm temperature to germinate well. Room temperature (25C/77F) works well. Sow the seeds in a well-drained mix and slightly cover with the mix. The papery wings that surround the seeds do not need to be removed. After sowing, place the pots in a tray with water and allow the medium to soak thoroughly. Above watering can dislodge the seeds and cause them to float to the surface. The seeds are most viable when planted within 1 year, although they can remain viable for longer. Allow a dry summer dormancy for the winter growing species and a dry winter dormancy for the summer growing species. It is probably best to not transplant the seedlings until they have completed their second season of growth. Representatives of some of the species are shown below.
Information on named species can be found on the wiki pages below or by clicking on the name of the species in the table.
More photos of representative species are shown below.
Southern African Gladiolus A-B - Southern African Gladiolus Ca - Southern African Gladiolus Ce-E - Southern African Gladiolus F-H - Southern African Gladiolus I-Me - Southern African Gladiolus Mi-Pa - Southern African Gladiolus Pe-R - Southern African Gladiolus S-T - Southern African Gladiolus U-Z - Gladiolus Hybrids - Miscellaneous Gladiolus