The Calla Lily (Zantedeschia) is an ornamental plant prized for its elegant, trumpet-shaped spathes and striking foliage. While most gardeners propagate Calla Lilies by dividing underground rhizomes, growing them from seed offers a distinct challenge. This approach allows for the cultivation of unique genetic variations and is necessary for starting specific hybrid seeds. Successful propagation requires patience and attention to specific pre-treatment and environmental conditions.
Preparing Calla Lily Seeds for Planting
The initial step involves securing viable seeds, either purchased or harvested from a mature plant. If harvesting, wait for the spent flower to develop into a berry-like seed head, which takes several months after pollination. The seed pod should turn yellow-brown or tan on the plant, indicating the seeds inside have reached maturity.
Once harvested, the individual seeds must be extracted from the soft, outer pulp. This process is necessary for successful germination. Each pod contains multiple seeds, which must be cleaned to remove all traces of the sticky fruit material before planting. The cleaned seeds have a hard, protective coat, which naturally prevents them from sprouting too early.
To break this natural dormancy and accelerate sprouting, the seeds require pre-treatment known as scarification. The most effective method is to soak them in lukewarm water for approximately 24 hours just before sowing. This soaking softens the tough seed coat, allowing water to penetrate the embryo and initiate germination. Most Zantedeschia cultivars do not benefit from cold stratification, so this simple warm-water soak is generally the only pre-planting preparation required.
Sowing Seeds and Ensuring Germination
Select a sterile, well-draining seed starting mix to prevent fungal issues like “damping off.” A recommended blend includes peat moss, perlite, and vermiculite, providing necessary aeration and moisture retention. Fill shallow trays or small pots with the moistened mix, ensuring containers have drainage holes to prevent waterlogging.
Plant the pre-soaked seeds shallowly, covering them with only about one-quarter to one-half inch of the starting medium. Covering seeds too deeply hinders the emerging sprout’s ability to reach the surface. After sowing, gently mist the surface to settle the soil without disturbing their placement.
Successful germination relies on maintaining consistent warmth and high humidity, mimicking the plant’s native subtropical environment. A temperature range of 70–75°F (21–24°C) is optimal for stimulating sprouting. Placing the seed tray on a heat mat helps maintain this necessary bottom warmth, especially indoors.
To ensure high humidity, cover the seed tray with a clear plastic dome or plastic wrap, acting as a miniature greenhouse to trap moisture. Place the trays in an area that receives bright, indirect light for 12 to 16 hours daily, often achieved using supplemental grow lights. Under these ideal conditions, Calla Lily seeds typically begin to germinate within 30 to 90 days.
Caring for Calla Lily Seedlings
After germination and the first sprouts emerge, remove the plastic covering to increase ventilation and prevent rot. The young seedlings are delicate and require a careful balance of moisture and air circulation. Keep the soil consistently moist, but allow the top layer to dry slightly between waterings to discourage fungal growth.
Once the seedlings develop their first set of true leaves, they can begin to receive very dilute applications of a balanced liquid fertilizer every two weeks. This gentle feeding regime supports the rapid growth and development of the initial rhizome structure. If multiple seeds were sown in a single pot, the young plants should be carefully thinned to allow only the strongest one to remain, preventing competition for resources.
When the seedlings have developed two or three true leaves and their root systems are robust, they must be transplanted into larger, individual pots. This transition provides the necessary space for the underground rhizome to begin forming and expanding. It is important to handle the tiny roots with care during this process to minimize shock.
A significant consideration when propagating Calla Lilies from seed is the extended timeline required before the plant reaches flowering maturity. Unlike plants grown from rhizomes, which can bloom in the first season, seed-grown Calla Lilies typically require a two-to-three-year period of vegetative growth before they are mature enough to produce their first spathe. This commitment to long-term cultivation is a key expectation for gardeners choosing the seed method.