Jennifer Schultz Nelson
Extension Educator, Horticulture
Just when you think that summer has spent its last bloom, gladiolus shows its colorful self. I had just about given up on mine until last week.
I thought the drought had gotten the best of them until lo and behold there were flower spikes on plants that I swear had none the day before. They are just starting to bloom and are a gorgeous shade of deep purple.
Technically speaking, gladioli (glads) are grown from corms, not bulbs. Structurally, corms are solid masses of compacted stems, not layered like true bulbs. The growing point is on the upper surface. Cormels are small corms that form at the base of the main corm each year, and may be used to propagate a given variety.
Glads are relatives of iris, and native to South Africa, but some wild species exist in southern Europe and the Near East. Glads display a wide variety of flower colors and shapes on flower spikes that range in size from two to six feet. Florets borne on these spikes range from one to eight inches in diameter.
As with most plants, well-drained soil is a must to prevent rot in glads. Gladiolus corms may be dipped in a fungicidal solution before planting as further insurance against rot.
Other than general plant needs like providing at least one inch of water per week, fertilizing at a rate of 2 pounds of well-balanced fertilizer per 100 square feet, glads require minimum care. Some flower spikes may need staking to prevent breakage. Blooming spikes make beautiful long-lasting cut flowers.
Glads should be dug in the fall about six weeks after flowering, when the foliage begins to yellow. They should be cured in a warm well-ventilated location until outer surfaces are thoroughly dry. After that, storage in a cool 35-45 degree room is recommended. Old corm growth and cormels may be broken off the new corm growth at this time. The old corm may be discarded.