Plant Profile: Gladiolus

Gladiolus, commonly referred to as gladiolas, is a genus of flowering bulbs characterized by their sword-like green leaves, which form upright fans about two inches long, and their funnel-shaped blossoms that bloom sequentially from the bottom to the top on slender stems during the summer and early fall. These fragrant flowers are not only beautiful but also make for stunning cut arrangements. While the bulbs can survive winter in USDA zones 7 to 10, for optimal flowering, it is advisable to treat the corms as annuals by lifting them in the fall and replanting them after the last frost of the following spring. They fall under the Tender III classification and are susceptible to damage when temperatures drop below 25 degrees Fahrenheit (2 degrees Celsius).

This genus encompasses over 300 species, showcasing a diverse palette of flower colors, including white, cream, yellow, orange, red, pink, lavender, purple, and green, which are categorized into three primary hybrid groups.

Gladiolas thrive best in full sun or afternoon shade, sheltered from strong winds, and prefer rich, well-drained soil, although they can adapt to various soil types, except for heavy clay. They flourish in moist borders. Corms can be started indoors in early spring or planted directly in the ground after the last frost. It’s important to wait until the soil warms up and to make staggered plantings to prolong the blooming period. For planting, place small corms 2 to 3 inches deep and larger corms 5 to 6 inches deep, ensuring they are spaced 5 to 8 inches apart, regardless of their size.

During the growing season, maintain consistent moisture and avoid letting the soil dry out. Once blooming has finished, reduce watering. When the foliage begins to yellow and before the first significant frost, carefully dig up the corms, trim off the stems and leaves, separate the cormels (the small corms at the base), and allow the corms and cormels to dry. Discard any that are diseased or damaged, and store the healthy ones in a dry medium in a cool, frost-free area for the winter.

**Diseases, Insects, and Other Plant Issues:**
Gladiolus are prone to various issues, including Botrytis, crown rot, rust, wilt, and mosaic virus. Keep an eye out for pests such as aphids, mealybugs, spider mites, and thrips. If thrips or fungal problems occurred during the growing season, it may be wise to treat the corms with an insecticide or fungicide before storing them.