Gladiolus cormels are small offsets, miniature versions of the parent corm, that develop at the base of the mature storage organ. They represent a natural method for the plant to multiply, allowing gardeners to increase their stock of a specific variety. Propagating gladiolus this way is a long-term project because these immature structures require time to develop. Cormels typically need one or two full growing seasons after planting to reach the size necessary to produce a flowering spike.
Initial Processing and Curing
Handling cormels begins in autumn after the foliage yellows and dies back, typically following the first light frost. This timing ensures the plant has successfully transferred maximum energy reserves back into the corms and cormels for dormancy. Once dug up, gently shake the soil off the root mass, avoiding damage to the underground structures. The remaining stem is then trimmed back to a short stub, about one to two inches above the corm.
The next step involves separating the cormels from the parent corm, though this can also be done after the curing process is complete. Whether separated now or later, the cormels must be spread out in a single layer to begin the curing process. Curing is a period of controlled drying that hardens the outer skin, creating a protective layer that minimizes moisture loss and reduces the risk of fungal rot during storage.
This phase requires a warm, dry environment with good air circulation, away from direct sunlight, with a suggested temperature range of 70 to 80°F (21 to 27°C). The cormels should be cured for approximately two to three weeks until the outer husk feels dry and papery to the touch. Once adequately cured, the older, shriveled mother corm, which is now depleted, can be easily removed and discarded. Inspect the cormels closely at this point, discarding any that appear soft, moldy, or shriveled, as only firm, healthy stock should be saved.
Overwintering Storage Conditions
Overwintering cormels requires a cool, dry, and consistently ventilated environment to keep them dormant and prevent spoilage. The ideal storage temperature is typically between 35 and 45°F (2 and 7°C), keeping the material dormant without risking freeze damage. Temperatures that are too warm can cause the cormels to break dormancy prematurely, while freezing temperatures will destroy the tissue. Storage areas such as an unheated basement, root cellar, or a refrigerator vegetable bin can work, provided they stay within this range.
The tiny cormels must be stored in a medium that allows air to circulate freely around them to prevent the buildup of moisture that encourages mold and rot. Appropriate containers include paper bags, cloth sacks, or mesh bags, which can be hung or stacked to ensure ventilation. Avoid using sealed plastic bags or containers, as these trap humidity and condensation, leading to fungal growth.
The cormels should be checked periodically, perhaps once a month throughout the winter, to monitor their condition. Any cormels showing signs of decay, such as becoming soft or mushy, should be removed immediately to prevent the spread of pathogens. If the cormels appear to be shriveling excessively, a slight increase in ambient humidity may be necessary, though they generally prefer dry conditions.
Spring Planting for Growth
Once spring arrives and the danger of hard frost has passed, cormels are ready to be planted outdoors in a prepared growing bed. Planting should occur once the soil temperature has warmed to at least 55°F (13°C), which encourages active root growth. Unlike mature corms, which are planted deeper, the small cormels only need to be covered by about one and a half to two inches of soil.
Due to their small size and the goal of maximizing growth, cormels can be planted closer together than mature flowering corms, which are typically spaced six to ten inches apart. Planting them more densely in a dedicated nursery bed allows for efficient care and management during their first year of development. The planting location should offer full sunlight and feature well-drained soil, which is a requirement for all gladiolus to prevent rot.
The initial growing season focuses on vegetative growth, encouraging the development of a large, healthy corm capable of supporting a flower spike in future years. Consistent moisture is important for the small cormels, especially during dry spells, to support continuous leaf development. A balanced fertilizer can be applied when the initial foliage reaches a height of several inches to fuel corm enlargement.
These immature cormels will primarily produce only foliage during the first year. The energy from this season is directed toward increasing the size of the storage organ, growing the cormel into a small corm. These newly grown, larger corms must then be dug up in the fall, cured, and stored over a second winter. They are replanted the following spring, at which point they should reach flowering size.