This gladiolus of the Grandiflorus group is one of the beautiful bi-color varieties. Download a large version (800x600) of this image.
The genus Gladiolus includes about 180 species and more than 10,000 named cultivars. Gladioli grow from corms (bulblike swollen underground stems), producing sword shaped leaves arranged in basal fans. The flowers are borne on upright spikes, usually one per corm, opening from the bottom upward, usually with several open at a time. Each flower consists of six tepals of unequal sizes and shapes. The flowers are bilaterally (as opposed to radially) symmetrical. Flower colors may be white, mauve, green, yellow, orange, red, pink or purple, often with blotches or stripes of another color. Some gladioli have scented flowers. The gladiolus species are rarely found in cultivation; instead, gladioli that you are apt to find in the trade are hybrids of complex, often long forgotten parentage. The many cultivars are classified into three major groups: Nanus, Primulinus and Grandiflorus. Hybrids and cultivars in the Nanus group bloom in early summer with two or three 9-14 in (22-35 cm) spikes per corm, each spike bearing 3-5 open flowers at a time. Those in the Primulinus group bloom in midsummer with a single very slender 12-24 in (30-60 cm) stem per corm; the stem bears as many as 20 buds with up to 7 open at a time. Hybrids and cultivars in the Grandiflorus group bloom from late spring through autumn with up to 28 buds on (usually) a single spike, usually 14-36 in (35-90 cm) tall. As many as a dozen flowers may be open at a time. Gladioli within the Grandiflorus group are further classified by color and flower size in an elaborate trinomial system, with the first digit indicating size; the second color; and the third intensity of color. Some of the largest Grandiflorus cultivars can get up to 5.5 ft (1.7 m) tall, while some miniatures don't reach 36 in (90 cm) in height.
The parrot gladiolus or Natal lily (G. dalenii is a common gladiolus species in the southern U.S., often persisting in abandoned gardens or roadsides with no care at all. Its beautiful orange and yellow flowers are borne on 3 ft (1 m) spikes.
The Grandiflorus glads come in a rainbow of colors and sizes. Click to download a large wet white one for your computer desktop.
The wild species of gladioli are native to the Mediterranean region, the Middle East, western Asia, Madagascar and (especially) South Africa. Most of the more than 10,000 named cultivars probably were derived from just seven species native to South Africa and first brought to European gardens in the late 1600's. The extensive hybridization and selection of gladioli was poorly documented and the parentage of most modern cultivars is now unknown.
Although technically perennials, gladioli corms are often lifted after flowering and replanted the following spring since the corms survive summers poorly in the hot south and winters poorly in the cold north. The taller cultivars should be protected from wind, and may need to be staked. Light: Gladioli should be planted in full sun, although partial shade is tolerated. Moisture: Grow gladioli in fertile, well drained soil with normal watering. Hardiness: USDA Zones 7-10. Gladioli corms cannot survive where the soil freezes deeply. The corms can be protected to zone 7 or even 6 if mulched well. Otherwise, they should be dug before the soil freezes and stored indoors for replanting in spring. Dig up the corms six weeks after blooming, cut off the stems and leaves, dip in fungicide and keep dry until replanting. Propagation: Cormlets can be separated from the main corm when the plants are dormant. Seed can be started in spring. Plant corms 3-6 in (8-15 cm) deep, and about the same distance apart in spring.
Deer and rabbits don't seem to have a taste for gladiolus although they do enjoy knocking them over as they dine on adjacent plants. Click to download a large version of this really red Grandiflorus glad.
Gladioli are best grown in clumps in mixed borders or beds. They are often grown as annuals, with new corms planted out each spring. Plant large corms every two weeks throughout the early spring in order to have flowers for display or cutting most of the summer. Parrot gladiolus will thrive and even multiply in the South. Many kinds of gladioli make ideal cut flowers, and can be grown in rows in the cutting garden. When cutting stems be sure to leave a half dozen or so leaves to nourish the corms during the remainder of the growing season.
Gladioli are sometimes called sword lilies, and the name means "little sword" in Latin. The North American Gladiolus Council (www.gladworld.org) is an umbrella organization for gladiolus societies all over North America and a good way to dive deeper into the beautiful world of sword lilies.