The Calla lily (Zantedeschia) is a popular plant for garden beds and containers that is easily multiplied. Propagation is achieved through two primary methods: dividing its subterranean rhizomes or, less commonly, sowing seeds. Division offers a direct and reliable way to expand a collection, while growing from seed allows for experimentation with new genetic variations.
Propagation by Dividing Rhizomes
The most reliable method for expanding Calla lily collections is by dividing the thick, fleshy, tuber-like rhizomes. This process yields genetically identical clones and is typically performed during the plant’s dormant cycle. Divide them either in the late fall after the foliage has died back or in the early spring before new growth begins.
To begin, carefully lift the entire rhizome clump from the soil using a garden fork, avoiding slicing the underground mass. Gently brush or rinse away excess soil to expose the rhizome structure. Identify the “eyes,” which are small, bud-like growth points where new shoots will emerge.
Using a sharp, clean knife or shears, divide the rhizome into sections. Ensure each piece retains at least one distinct eye and a portion of the root mass. Sterilize the cutting tool with rubbing alcohol before and after each cut to prevent transmitting pathogens. Discard any soft, discolored, or damaged sections.
After division, prepare the cut surfaces to prevent rot upon replanting. Allow the divisions to dry in a cool, shaded, and well-ventilated location for one to two days until a protective layer, known as a callus, forms over the tissue. Dusting the cut surfaces with a natural fungicide, such as garden sulfur, offers protection against soil-borne diseases. Once callused, replant the new rhizomes with the eye facing upward, typically buried three to four inches deep in the soil.
Starting Calla Lilies from Seed
Growing Calla lilies from seed is a slower process, usually reserved for generating new color variations or hybridizing, since the resulting plants will not be identical to the parent. Seeds are harvested from the mature, dried pods on spent flower stalks and require pre-treatment to encourage germination. Soaking the seeds in warm water for 24 hours softens the tough outer coating, though some growers prefer the damp paper towel method.
Sow the seeds in a flat or small pots filled with a well-draining, moist seed-starting mix, then lightly cover them with about a quarter-inch of soil. The growing medium should be kept consistently warm, ideally between 70°F and 80°F, often requiring a heating mat. Seedlings may emerge within a few weeks, but it may take longer if the seeds were not pre-treated.
Plants grown from seed require patience, as seedlings spend their first few seasons developing their rhizome structure. The first flowering typically occurs two to three years after sowing. Because of this extended timeline, rhizome division remains the preferred method for quickly multiplying a collection.
Care Requirements for Newly Propagated Plants
Care for newly propagated Calla lilies focuses on establishing a healthy root system. After planting divided rhizomes or sowing seeds, lightly water the soil to settle the medium around the plant material. Keep the soil consistently moist but never waterlogged during this initial establishment phase, as excessive moisture can lead to rhizome rot.
For newly planted rhizome divisions, limit significant watering until new shoots visibly emerge, signaling active growth. Seedlings need consistent moisture immediately to support their fragile root systems and early leaf development. Both young plants should be placed in an area with bright, indirect light and protected from harsh sun or temperature extremes.
Approach fertilizer application cautiously during the establishment period. For divided rhizomes, wait until the new foliage is fully developed before applying a balanced liquid fertilizer. Seedlings benefit from a nutrient-rich potting mix but should not receive a high-nitrogen fertilizer, which promotes leafy growth at the expense of developing the rhizome and future flowers.