The Calla Lily (Zantedeschia), with its elegant, trumpet-shaped flowers, is a highly popular ornamental plant often grown in gardens and containers. For the colorful hybrid varieties, a period of dormancy is a necessary resting phase that allows the plant to conserve energy and prepare for the next season’s bloom cycle. Replicating the plant’s natural environmental cues is the key to successfully putting it to rest and ensuring its return.
Why Calla Lilies Require a Dormant Period
Dormancy is necessary because the Calla Lily’s native habitat has distinct wet and dry seasons. It is a survival mechanism, triggered by environmental factors like cooling temperatures, reduced light, and lack of water that mimics the dry season. This period allows the plant to cease active growth and retreat resources into the underground storage organ, the rhizome or tuber.
The rhizome functions as a reservoir, accumulating starches and nutrients during the growing season. This stored energy fuels robust growth and flowering when favorable conditions return, making the resting period an integral part of its life cycle. Without this rejuvenation phase, the plant will struggle to bloom, resulting in weak growth and diminished flowers the following year. Hybrid varieties must undergo this dormancy to maintain vigor and health.
Preparing the Plant for Rest
Initiating dormancy begins with the gradual reduction of water after flowering concludes, typically in late summer or early fall. Excessive watering at this stage can prevent the plant from entering its resting cycle and increase the risk of rhizome rotting. The plant naturally signals the start of dormancy as its foliage begins to yellow and then brown.
Yellowing indicates the plant is actively reabsorbing nutrients and energy from the leaves back into the rhizome for storage. Allow the leaves to die back completely before cutting them, as prematurely removing green foliage deprives the rhizome of stored food reserves. Once the leaves are entirely brown and dry, cut the foliage and stems back to about one to two inches above the soil level.
Proper Storage During Dormancy
After the foliage is cut back, lift the rhizomes from the soil to prevent freezing in colder climates (generally USDA Zones 7 and below). Carefully dig them up, taking care not to damage the fleshy tissue, and gently brush away any loose soil. Do not wash the rhizomes, as introducing moisture significantly increases the risk of fungal rot during storage.
Curing is the next step, where rhizomes dry in a warm, well-ventilated area away from direct sunlight for seven to ten days. Curing forms a tough, protective outer skin that seals the rhizome against pathogens and moisture loss. After curing, store the rhizomes in a vented container, such as a paper bag, mesh bag, or cardboard box, to ensure proper air circulation.
Storage Medium and Temperature
Layer the rhizomes with a dry storage medium like peat moss, vermiculite, or sawdust. This maintains a stable, slightly humid environment and prevents them from completely desiccating. The ideal storage temperature range is between 40 and 50 degrees Fahrenheit, as warmer temperatures can encourage premature sprouting.
Monitoring
Periodically check the rhizomes throughout the winter for any signs of mold or shriveling. Lightly mist the storage medium if they appear too dry.
Reawakening the Calla Lily
The dormant period concludes when the rhizomes are ready to be replanted, typically in late winter or early spring, about four to six weeks before the last expected frost. Before planting, visually inspect each rhizome, discarding any that show signs of severe rot or excessive shriveling. Minor soft spots can be carefully cut away with a sterile knife, allowing the cut surface to dry before planting.
To signal the end of the resting phase, plant the rhizomes in containers using a rich, well-draining potting mix. Place them about one and a half to two inches deep with the growing tips facing upward. Initially, water the soil sparingly until new leaf growth emerges, as this gradual reintroduction of moisture prevents the dormant rhizomes from rotting.
Place the containers in a warm, brightly lit location to encourage sprouting before moving them outdoors once all danger of frost has passed and soil temperatures have warmed. Once new shoots appear, you can gradually increase watering and begin a regular feeding schedule to support the new season of growth and flowering.