Gladiolus, often called “sword lilies” due to their distinctive foliage, are popular flowering plants known for their vibrant and stately blooms. These impressive flowers can add a dramatic vertical element to any garden. Understanding gladiolus growth stages, from corm to dormancy, aids successful cultivation and enjoyment.
From Corm to Sprout
Gladiolus begin as corms, swollen underground stems that store food. Selecting firm, healthy corms is important for vigorous growth. Corms are typically planted in spring after the last frost, when soil temperatures reach at least 55°F (13°C). A location with full sun and well-draining soil is ideal for planting.
Planting depth usually ranges from 4 to 6 inches, with larger corms planted deeper, and spacing them 3 to 6 inches apart. After planting, thorough watering helps settle the soil around the corms. Within approximately two to three weeks, the corm establishes roots and sends up its first bright green shoot, signaling active growth.
Developing Foliage
After sprouting, gladiolus plants rapidly develop their characteristic sword-like leaves. These long, narrow leaves are crucial for photosynthesis, converting sunlight into energy that fuels the plant’s overall development. Healthy foliage links directly to robust flower stalks.
During this vegetative stage, consistent moisture is beneficial, especially during dry periods, with deep watering once or twice a week. Gladiolus benefit from a balanced feeding schedule to support this vigorous leaf growth. As the foliage matures and grows taller, staking becomes necessary for many gladiolus varieties to prevent them from falling over, especially in windy conditions.
Flower Stalk and Bud Formation
Flower stalks emerge 60 to 90 days after planting, though this can vary with the specific gladiolus variety. The stalk grows from the center of the developing foliage, gradually elongating before flower buds begin to form along its length. These buds appear sequentially, leading to a stately spike of potential blooms.
Continued support through staking is important as the flower stalk gains height and density to bear the weight of the developing florets. Adequate water and nutrients remain important during this period to support the significant energy demands associated with forming numerous flowers. Providing a liquid feed high in potassium can help promote flowering as the spikes emerge.
The Blooming Period
The blooming period showcases a wide array of colors and forms. Each flower spike typically blooms for about one to two weeks, with individual florets opening sequentially from the bottom upwards. This staggered opening allows for an extended display of color on each stalk.
For those wishing to enjoy gladiolus indoors, cutting the flowers when the first one or two florets begin to open ensures the longest vase life. When cutting, leaving at least four leaves on the plant is important; this allows the remaining foliage to continue photosynthesizing and storing energy in the corm for the following growing season. Consistent moisture in the soil contributes to prolonged and vibrant blooms.
Post-Bloom Care and Seed Pods
After the vibrant blooms fade, proper post-bloom care helps redirect the plant’s energy. Removing the spent flower stalks, a practice known as deadheading, is generally advised unless seed collection is desired. Deadheading prevents the plant from expending energy on seed formation, allowing it to focus on storing nutrients in the corm for future growth.
If seed collection is a goal, the faded flower stalk can be left on the plant to allow seed pods to develop. These pods will swell and eventually turn brown, indicating that the seeds inside are maturing. Growing gladiolus from seed is a lengthy process, often taking two to five years to produce flowers, as the plant prioritizes corm development. Regardless of seed collection, watering should continue until the foliage naturally yellows, indicating the plant is preparing for dormancy.
Preparing for Dormancy: Digging and Storage
For most climates, preparing gladiolus for dormancy involves digging up the corms. It is important to allow the foliage to yellow and die back naturally, typically six weeks after blooming, as this process ensures energy is transferred from the leaves back into the corm. This energy storage is important for the corm’s viability and future blooms.
Corms should be carefully dug up before the first hard frost, typically in late summer or early fall. After lifting, gently shake off excess soil and trim the stems to about one to two inches above the corm. The corms then need to cure or dry in a warm, well-ventilated area for two to three weeks. Once cured, remove any old, shriveled mother corms and store the new, healthy corms in a cool, dry, dark, and well-ventilated place, such as mesh bags or paper boxes, at temperatures between 35°F and 50°F (2°C to 10°C) for the winter. In warmer, frost-free climates (USDA Zones 8-10), gladiolus corms may be left in the ground to overwinter.