Gladiolus, often called “sword lilies,” are popular garden additions known for their tall, striking flower spikes. For many gardeners, propagation offers a practical way to multiply gladiolus, allowing enthusiasts to expand their displays or share with others. This process involves utilizing the plant’s natural reproductive structures to create new, genetically identical individuals.
Understanding Gladiolus Corms and Cormels
Gladiolus plants grow from structures known as corms, which are often mistaken for bulbs. A corm is a swollen, underground stem base, serving as a storage organ for nutrients that fuel the plant’s growth and flowering. Unlike a true bulb, which has fleshy scales, a corm is a solid mass of stem tissue, typically flattened and covered by a dry, papery tunic. This corm acts as the primary reproductive unit for the mature plant.
During the growing season, the main gladiolus corm naturally forms smaller cormels (also referred to as cormlets or bulblets). These cormels emerge around the basal plate of the parent corm. Each cormel is essentially a clone of the parent plant, containing all the genetic material needed to grow into a full-sized gladiolus. They represent the plant’s natural method of vegetative reproduction.
Propagating Gladiolus from Cormels
Propagating gladiolus from cormels is an effective way to significantly increase your plant stock. The process begins in late fall, typically after the foliage has naturally yellowed and died back, signifying that the plant has stored sufficient energy in its corms. At this point, carefully dig up the main corms from the soil, gently shaking off any excess dirt. You will observe numerous small cormels attached to the base of the primary corm.
Separate these cormels from the parent corm by gently twisting or breaking them off. Clean them thoroughly, removing any clinging soil or old plant debris. After cleaning, allow the cormels to air dry in a well-ventilated area for approximately two to three weeks; this curing period helps to harden their outer layers and reduce the risk of rot during storage. Once cured, store the cormels in a cool, dry, and dark location, ideally between 40-50°F (4-10°C), within mesh bags or nylon stockings for air circulation through winter.
In the spring, once the danger of frost has passed and soil temperatures have consistently reached at least 55°F (13°C), the stored cormels are ready for planting. Prepare a planting bed with well-draining soil, ideally amended with compost to improve fertility and drainage. Plant the cormels approximately 3 to 4 inches deep and space them about 4 to 6 inches apart. While cormels offer a high success rate for propagation, they usually require one to three growing seasons to mature and produce their first flowers.
Propagating Gladiolus by Division
While cormels are the primary means for increasing the number of gladiolus plants, mature corms can also be propagated through division. This method is suitable for larger, older corms that have developed multiple distinct “eyes” or growth points. Division is less about mass propagation and more about refreshing existing stock or separating naturally formed clusters of corms. It helps to maintain the vigor of older plants by preventing overcrowding.
The ideal time to divide gladiolus corms is in the spring, just before the typical planting season begins. Carefully inspect large corms for natural constrictions or clear divisions where multiple growth points are evident. Using a sharp, clean knife, cut the corm into sections, ensuring that each piece retains at least one healthy eye and a portion of the basal plate, which is the flat bottom part from which roots emerge. After cutting, allow the newly divided sections to air dry for a day or two, which helps the cut surfaces to callus over and reduces the risk of fungal infections once planted.
Caring for Newly Propagated Gladiolus
Proper care is essential for newly propagated gladiolus, whether grown from cormels or divided corms, to ensure their successful establishment and growth. Young gladiolus plants thrive in locations that receive full sunlight for at least six to eight hours daily, which is crucial for robust development and future flowering. The soil plays a significant role in their health, requiring excellent drainage to prevent waterlogging, ideally a sandy loam rich in organic matter. Amending heavy clay soils with compost or sand can significantly improve their suitability.
Consistent moisture is important for young gladiolus, particularly during dry spells, but overwatering must be avoided. Water deeply when the top inch of soil feels dry to the touch, ensuring the moisture reaches the root zone without saturating the area. Newly emerged plants benefit from a balanced liquid fertilizer, applied at half the recommended strength, every two to three weeks during their active growth phase to support their development. Vigilance against common pests like thrips and early detection of fungal diseases can help protect these vulnerable young plants.
Common Propagation Challenges
Gardeners may encounter several challenges when propagating gladiolus, particularly with cormels, which can affect success rates. One common issue is the failure of cormels to sprout, often due to improper storage conditions, such as temperatures that are too warm or too cold, which can reduce their viability. Additionally, planting cormels too deep or in overly cold soil can delay or prevent germination, as they require specific warmth to break dormancy.
Another frequent problem is corm or cormel rot, which typically occurs post-harvest or during storage. This is often a result of insufficient drying or curing before storage, leading to fungal or bacterial infections in damp conditions. Excessive moisture in the planting bed can also cause newly planted corms or cormels to rot before they have a chance to establish roots. Young plants might also lack vigor, sometimes stemming from insufficient light, poor soil nutrition, or competition from weeds. Addressing these factors with proper preparation and environmental control can significantly improve propagation outcomes.