Calla Lilies (Zantedeschia species) are grown worldwide for their elegant, colorful blooms. Although often treated as annuals in cooler climates, these tender perennials require a period of dormancy to rest and replenish energy reserves after flowering. This natural cycle is typically triggered by cooling temperatures and reduced water availability following the peak blooming season. Correctly managing this phase is paramount for ensuring the plant’s health and vibrant return the following season.
Recognizing and Initiating Dormancy
The first indication that a Calla Lily is preparing for dormancy is the yellowing and eventual browning of the foliage. This dieback signals that the plant is withdrawing nutrients from its leaves back into the underground storage structure, the rhizome. Gardeners should allow the leaves to fully yellow and collapse before intervention to ensure maximum nutrient reabsorption.
Dormancy initiation begins in late fall or early winter, often right after flowering. At this time, gradually reduce the amount of water the plant receives. Withholding water signals the rhizome that the growing season is concluding, prompting the resting state. Once the foliage has completely died back and turned brown, it can be cut cleanly away at the soil level.
Safe Storage of Calla Lily Tubers
Gardeners in USDA hardiness zones 7 and below must lift the rhizomes from the ground, as these tropical plants will not tolerate freezing temperatures. The ideal time for lifting is shortly after the first light frost kills the top foliage, confirming the rhizome has stored all available energy. Use a garden fork for lifting to minimize the chance of damaging the rhizomes.
After lifting, gently clean the rhizomes by brushing away the soil; avoid washing them with water, which encourages rot. The next stage is curing, which involves allowing the rhizomes to dry out for seven to ten days in a warm, well-ventilated area. Curing helps the outer skin (rind) toughen, providing a protective layer during winter storage. This should take place out of direct sunlight, ideally at temperatures between 60 and 70 degrees Fahrenheit.
Once cured, store the rhizomes in a cool, dark, and frost-free environment, maintained between 40 and 50 degrees Fahrenheit. Use a vented container, such as a cardboard box or paper bag, to prevent moisture buildup and ensure air circulation. Layer the rhizomes in a dry, loose medium such as peat moss, vermiculite, or sawdust to protect them and regulate humidity. Periodically check the stored rhizomes throughout the winter to ensure they are not shriveling or developing mold.
Managing Dormancy for Potted Calla Lilies
Care for container-grown Calla Lilies is simpler than for in-ground plants, as the rhizomes remain in the pot for the rest period. Once the foliage begins to yellow in the fall, reduce watering significantly, stopping altogether when the leaves die back. The lack of moisture, light, and temperature reduction forces the plant into dormancy.
Move the container to a cool, dark, and dry location, such as a basement or unheated garage. This resting environment should maintain temperatures consistently between 40 and 50 degrees Fahrenheit for two to three months. Ensure the location is completely frost-free, as freezing temperatures will damage the rhizomes. During dormancy, no water is typically supplied, but occasional light misting may be necessary if the soil becomes excessively dry.
Reintroducing Growth in Spring
Ending dormancy should begin in late winter or early spring, allowing the plant to establish itself before summer heat. Stored rhizomes can be removed from their medium and replanted indoors several weeks before the last expected frost. Replant them in rich, well-draining soil, setting them 1.5 to 4 inches deep with the growing tips (“eyes”) facing upward.
Initial watering of the newly planted rhizomes should be done sparingly until the first shoots emerge. Once growth is visible, gradually increase watering and move the container to a bright, warm location. For potted Calla Lilies that overwintered in their containers, move the pot from its dark storage location to a brighter area and resume a gradual watering schedule. Increased water and light exposure signals the plant to break its resting phase and begin its new cycle of growth.