Canna Lilies are striking, tropical or subtropical flowering plants prized for their large, paddle-shaped foliage and vibrant, showy blooms. These plants multiply with great vigor, relying almost entirely on specialized underground structures. The primary method of multiplication occurs beneath the soil surface through asexual reproduction.
How Canna Lilies Multiply Underground
Canna Lilies multiply naturally using a structure called a rhizome, which is not a true bulb but a modified subterranean stem. This horizontal stem serves as a storage unit for starches and carbohydrates, allowing the plant to survive periods of dormancy. New growth points, commonly referred to as “eyes,” develop laterally along the length of the parent rhizome. Each eye contains meristematic material capable of producing an entirely new, genetically identical Canna plant. The rhizome continually expands outward, producing new shoots that result in the plant’s characteristic clumping growth pattern.
Managing Multiplication Through Division
Because Canna Lilies multiply so rapidly underground, gardeners often need to manage this spread through division. This process is the most effective way to control plant size, rejuvenate older clumps, and increase plant stock while maintaining the parent plant’s exact characteristics. The ideal time for this intervention is either in the late fall after the foliage has died back from frost, or in the very early spring before new growth begins.
The manual division process involves several steps:
- The entire clump must be carefully dug up, taking care to avoid slicing into the brittle rhizomes.
- Excess soil should be gently removed to expose the swollen, starchy stems and clearly identify the growth points.
- The rhizome mass is then separated, either by hand for natural breaking points or by using a sharp, sanitized knife or shears.
- Each resulting division must contain at least one healthy eye; sections with two or three eyes will establish more quickly and produce a stronger plant.
- Any soft, damaged, or older, rootless sections of the rhizome should be discarded.
- Before replanting or storing, the cut surfaces should air-dry for a few days to form a protective layer, which helps prevent rot and fungal infection.
- The new divisions are then replanted shallowly, typically one to two inches deep, with the eyes facing upward.
Environmental Factors and Seed Propagation
The rate at which Canna Lilies multiply through their rhizomes is influenced by external environmental conditions. Maximum multiplication speed occurs when the plants receive a minimum of six hours of full sunlight daily, coupled with rich, organically fertile soil. Adequate moisture is also a factor, as these plants thrive in consistently damp, well-drained locations. These conditions support the rapid expansion of the underground stems and the formation of new plants.
Seed Propagation
Propagation can also occur via seeds, representing the plant’s sexual reproduction method, but this is secondary and less predictable. Canna seeds possess an extremely hard, protective outer coat, which must be manually nicked or scarified to initiate germination. Plants grown from seeds take longer to mature and may not produce flowers or foliage identical to the parent plant due to genetic recombination. Therefore, for reliably identical and quick multiplication, division of the rhizome remains the established method.