Gladiolus have four foot tall flower spikes that are ideal for bouquets. The gaudy blooms grow from a plant starting from a bulb-like structure called a “corm”. Gladiolus are native to South Africa and grow best on a sunny site in sandy loam soil with good water drainage. The bulbs can be purchased by the bag in the spring. Many bright colors and multicolor varieties are available.
Plant new bulbs every two weeks to extend bloom season.
For a continual harvest of flower spikes, plant a few corms every two weeks until early summer. Plant corms two to three inches deep, depending on their size, and cover with soil. Space corms eight inches apart groups of six to 15 corms. Once the plants are about 6 inches high, hill up the soil around the base of the plant to help support the stem.
Apply a liquid fertilize or manure tea five inches away from the stems when the plants are six inches tall. Apply a second application when the flower spikes start to show color. Keep the plants weed-free and mulched with a 2- to 4-inch-thick layer of bark mulch, wood shavings or straw. Keep plants well watered to produce the largest flowers. Tall varieties will probably need staking to prevent the flower spikes from falling over in the wind.
Gladiolus make wonderful cut flowers.
If you’re growing gladiolus so you can cut blooms for bouquets, flower spikes should be cut on a slant when the lowest flowers on the stalk begin to show color. When cutting the flower stalk, leave at least four leaves on the plant to feed the corm for next year’s blooms.
Gladiolus are not winter hardy, but can sometimes survive mild winters if heavily mulched. In USDA zones seven and eight, mulch gladiolus beds for protection. In USDA zones five and six, except for the hardy gladiolus varieties, dig up the corms for winter storage before the first heavy frost.
Clean the corms, cut the stalk within half an inch of the corm, and let them cure for one to two weeks in a warm, airy location. When dry, remove and discard the old corm as well as any small corms. Store the large, new corms in plastic mesh bags in a well-ventilated room where temperatures remain from 35 to 50 degrees F.
Gladiolus gets its name from its long narrow leaves that resemble sword blades. The ancient Roman armies used swords called “gladius” (from which the word “gladiator” is derived).and manure into planting beds in spring to help feed the growing plants. Gladiolus can be planted about two weeks before the last expected spring frost. It will take 70 to 90 days from planting until flowering. Bees, butterflies, and hummingbirds are all attracted by the flowers.