Canna lilies (Canna species) are highly valued garden plants known for their bold, tropical foliage and vibrant flowers in shades of red, orange, and yellow. Often mistakenly called bulbs, these striking plants actually grow from a specialized underground structure that allows them to store energy and survive dormancy. Gardeners frequently seek to multiply their cannas to expand a display or share with others. While many plants can be grown from a simple stem or leaf cutting, growing a canna lily using this technique is generally unsuccessful; the plant’s unique botany dictates a different, more reliable approach. The most effective way to create new canna plants is through the separation of their subterranean stems, known as rhizome division.
Why Stem Cuttings Are Not Used
Canna lilies are botanically classified as monocots, a group of flowering plants that includes grasses, palms, and gingers. Unlike many herbaceous plants that are easily propagated from a section of stem, cannas lack the necessary structures in their above-ground stalks to readily form new roots. The large, paddle-shaped leaves and erect stalks emerge directly from the rhizome, which is a modified, horizontal stem that grows beneath the soil surface. This rhizome serves as the plant’s primary organ for both energy storage and vegetative reproduction.
New canna growth originates from dormant buds, called “eyes,” that are scattered along the surface of the rhizome. These eyes are the only points from which a new plant can develop its own root and shoot system. Since the fleshy rhizome contains these growth points and the stored starches needed to fuel initial growth, the main body of the plant does not possess the same ability to regenerate from a simple stem cutting. Therefore, propagation must focus on dividing the rhizome to ensure each new piece carries at least one of these viable growth points.
The Primary Method: Rhizome Division
Propagating canna lilies is best achieved by dividing the mature rhizome clump, a process that should ideally be performed every three to five years to prevent overcrowding and maintain plant vigor. Division should occur either in the fall after the foliage has died back and the plant enters dormancy, or in the late winter to early spring before new growth begins. Dividing in early spring allows the new sections to establish quickly once soil temperatures rise.
Select a healthy, well-established parent clump that shows no signs of pests or disease. You will need a sharp, sterilized cutting tool, such as a garden knife or secateurs, to ensure clean cuts that minimize the risk of infection. Sterilizing the blade with rubbing alcohol before and between cuts prevents the transmission of fungal or bacterial pathogens. The fleshy nature of the rhizome makes it susceptible to rot, which is a common issue during the division process.
Step-by-Step Guide to Division
Start by carefully digging up the rhizome clump, working far enough away from the main stems to avoid damaging the roots. Once the mass is lifted, gently shake or rinse away the excess soil to expose the structure of the connected rhizomes and the location of the eyes. The above-ground foliage should be cut back to a short stub, typically about an inch or two above the crown, to focus the plant’s energy on root and shoot development.
Inspect the clump and identify the plump, rounded growth points—the “eyes.” Using your sterile knife, cut the rhizome into smaller sections, ensuring that each new piece has at least one, and preferably two or three, healthy eyes. Larger pieces with multiple eyes generally have more stored energy and a higher success rate for establishment.
After making the cuts, the newly separated sections should be allowed to dry in a cool, shaded place for several days. This drying time allows the cut surfaces to form a protective layer, known as a callus, which acts as a barrier against soil-borne fungi and decay. Some gardeners dust the cut surfaces with a fungicide or sulfur powder before letting them callus. Once the cuts appear dry and slightly tougher, the new rhizome divisions are ready for planting.
Post-Planting Care for New Growth
The divided rhizomes should not be planted until the soil temperature has consistently reached at least 60°F, as planting too early in cold, wet soil can lead to rot. Canna lilies thrive in full sun, requiring a minimum of six to eight hours of direct sunlight daily to reach their flowering potential. Select a location with rich, well-draining soil that remains consistently moist throughout the growing season.
Plant the rhizome sections horizontally, positioning them about four to six inches deep in the prepared soil, with the eyes facing upward. After planting, water the area thoroughly to settle the soil around the rhizome. Withhold further watering for up to two or three weeks until the first shoots begin to emerge from the ground. This period allows the rhizome to focus on root development without the risk of rotting in overly saturated soil. Once the plant breaks the surface, maintain deep, regular watering, providing a good soaking at least once a week during warm weather to support the plant’s rapid growth.