Canna lilies are tropical flowering plants known for their large leaves and vibrant blooms, providing a stunning, bold look in a garden. Although often mistakenly called “canna bulbs,” the plant actually grows from a rhizome. A rhizome is a modified underground stem that stores nutrients. Understanding the appearance and condition of this storage organ is the first step toward successful growth.
The Canna Rhizome: Appearance and Structure
The canna rhizome presents a distinct, often irregular appearance, resembling a thick, fleshy root, similar to the culinary ginger rhizome. It has a knobby, segmented structure that is usually elongated and grows horizontally beneath the soil surface. The texture is firm and dense, designed to store the starches and proteins the plant needs for energy.
The color of a healthy rhizome is typically a light, earthy shade, often described as cream, white, or light brown. Depending on the specific cultivar, some rhizomes may exhibit subtle reddish or purplish tints. A defining feature is the presence of growth nodes, commonly called “eyes,” which are small, slightly raised protrusions along the surface. These eyes are the points where new shoots and leaves will emerge upward and where roots will grow downward.
Rhizome size can vary significantly, ranging from small individual divisions to large, hand-sized masses. For propagation, the rhizome is often cut into sections, with each viable piece needing at least one, and ideally three to five, growth eyes to produce a strong plant. As the plant matures, the rhizome spreads laterally, expanding the canna clump over time.
How to Identify a Healthy Rhizome
Assessing the condition of a canna rhizome before planting or storage requires both visual inspection and tactile confirmation. A healthy rhizome should feel solid and firm when gently squeezed; any softness or mushy areas indicate rot, usually caused by excess moisture. The surface must be free from patches of fuzzy gray or white mold, signaling fungal issues.
Inspect the growth points, or eyes, which should be plump and visible, sometimes showing a pinkish or greenish tint if they are beginning to sprout. A rhizome that appears shriveled or dry is dehydrated, often due to poor storage conditions. While a dehydrated rhizome might still be viable, any piece that is blackened or emits a rotten smell should be discarded, as it will not grow.
Proper Planting Orientation
The physical structure of the canna rhizome dictates the correct way to position it for planting. Since the rhizome grows horizontally and the eyes are the emerging points for new shoots, the rhizome should be laid flat in the planting hole. Ensure that the growth nodes, or “eyes,” are facing upward toward the soil surface.
The planting depth is also guided by the rhizome’s structure, with the top typically covered by about two to three inches of soil. Planting too deeply can delay or stunt the plant’s emergence, as the new shoots must travel farther to reach the light. When planting multiple rhizomes, spacing them appropriately (generally 1 to 2 feet apart) allows the horizontal stems room to spread and develop new growth without overcrowding.