Calla lilies are popular ornamental plants known for their elegant, brightly colored blooms. Though beautiful in gardens and homes, these tender perennials cannot tolerate freezing temperatures. In many climates, winterization is necessary for their survival and vigorous return.
Understanding Calla Lily Winterization
Winterization is essential for calla lilies, as they are native to warmer regions and susceptible to frost. Their underground rhizomes, which store energy for future growth, can be damaged or destroyed by sustained cold. Protecting these rhizomes through colder months allows the plants to conserve energy and re-emerge robustly the following spring.
Preparing calla lilies for winter begins as outdoor temperatures consistently drop in autumn. Visual cues from the plant, such as yellowing and wilting foliage, indicate it is entering a dormant phase. Environmental triggers, such as the first light frost, also signal the time to begin winterization.
Preparing Calla Lilies for Dormancy
Before specific winterization methods, several preparatory steps apply to both in-ground and potted calla lilies. As autumn progresses and temperatures decline, gradually reduce watering. This signals the end of its active growing season and encourages dormancy.
Allow foliage to naturally yellow, wilt, and die back. This process enables the plant to draw nutrients from leaves back into the rhizome, strengthening it for dormancy. Once the foliage has completely browned and appears dry, cut it back to within a few inches of the soil line. This removal of dead material helps prevent fungal issues during storage or dormancy.
Winterizing Outdoor Calla Lilies
For in-ground calla lilies, winterization involves lifting rhizomes. After foliage has died back and cooler temperatures have passed, carefully dig around the plant with a garden fork, avoiding rhizome damage. Gently lift the entire clump from the soil, shaking off loose dirt.
Once lifted, rhizomes need to cure thoroughly to prevent rot. Place them in a single layer in a cool, dry, well-ventilated area, away from direct sunlight, for several days to a week. This drying period allows surface moisture to evaporate and helps harden the outer skin of the rhizome.
After curing, gently brush off any remaining soil but avoid washing the rhizomes. Store them in a material allowing air circulation, such as peat moss, vermiculite, or crumpled newspaper, within a mesh bag or cardboard box. The ideal storage location should be dark, frost-free, and maintain a consistent temperature of 40-50°F (4-10°C) for proper dormancy.
Winterizing Potted Calla Lilies
Potted calla lilies require a different winterization approach, primarily bringing containers indoors. Before the first hard frost, move the entire potted plant to a sheltered location, such as a garage, basement, or unheated sunroom. This protects the plant from freezing temperatures that can damage rhizomes within the pot.
Once indoors, gradually reduce watering to induce dormancy, similar to in-ground plants. Foliage will naturally yellow and die back as the plant enters its resting phase. Continue to withhold water as leaves completely brown and wither, signifying full dormancy.
During dormancy, potted calla lilies require minimal care. Place the container in a cool, dark location, such as a basement corner or an unheated closet, where temperatures remain consistently cool but above freezing. Watering should be withheld almost entirely, perhaps with only a light misting once a month if the soil is exceptionally dry, to prevent rhizome shriveling.
Bringing Calla Lilies Back in Spring
As spring approaches and frost threat diminishes, reawaken dormant calla lilies. For stored rhizomes, inspect them for signs of rot or disease before replanting. Discard any soft or moldy sections to prevent issues from spreading.
Replant healthy rhizomes outdoors after the last frost date for your region, typically when soil temperatures reach above 60°F (15°C). Plant them at a depth of about 4 inches, ensuring growing points face upwards.
For potted calla lilies overwintered indoors, gradually reintroduce them to light and water. Move the pot to a brighter, warmer location and begin watering sparingly, increasing the amount as new growth emerges. Once outdoor temperatures are consistently warm and all danger of frost has passed, move the potted calla lily back outdoors to continue its growing cycle.