The Calla Lily (Zantedeschia) is prized globally for its elegant, trumpet-shaped flower, which is actually a modified leaf called a spathe. Achieving consistent reblooming requires understanding the plant’s specific needs, which often differ between the common white variety and the vibrant colored hybrids. By managing the plant’s environment, nutrient intake, and annual rest period, gardeners can ensure the return of these striking blooms.
Setting the Stage: Light and Temperature Needs
The optimal light exposure for a Calla Lily depends heavily on its color variety. White Calla Lilies (Zantedeschia aethiopica) thrive in full sun, requiring a minimum of six hours of direct light daily for maximum flower production. In contrast, colored hybrids prefer a slightly more sheltered position. These colored varieties perform best in partial shade, needing protection from intense, midday sun which can scorch their leaves and fade the bloom color.
The plant’s temperature requirement favors conditions between 60 and 80 degrees Fahrenheit during its active growth phase. Temperatures that are too high can cause significant stress, leading to a decline in blooming. Conversely, Calla Lilies are tender and will enter a mandatory dormancy period when temperatures consistently drop below 50 degrees Fahrenheit.
Proper Feeding and Watering Practices
The type of fertilizer used is a major factor in triggering flower development versus excessive leaf growth. Calla Lilies that receive a high-nitrogen feed will produce lush foliage at the expense of their characteristic blooms. To encourage flowering, use a fertilizer with a lower first number in the NPK ratio, such as a 5-10-5 or a similar high-phosphorus formulation. Phosphorus is the element responsible for flower and root development, making it the most significant nutrient for reblooming.
During the active growing season, the plants require consistent and thorough watering. The soil should be kept evenly moist but never waterlogged, since this can quickly lead to rhizome rot. Using a rich, well-draining potting mix or amending garden soil helps maintain the necessary balance of moisture retention and aeration. Container-grown plants will require more frequent watering than those planted directly in the ground.
Managing the Dormancy Cycle for Reblooming
The most critical step for reblooming is providing a necessary period of dormancy. This resting phase allows the rhizome to regenerate the energy reserves required to form new flower buds for the next growing cycle. To induce dormancy in late summer or early fall, watering should be gradually withheld, allowing the foliage to naturally yellow and die back. This process ensures the plant pulls all available nutrients back into the underground rhizome for storage.
Once the foliage has completely withered, the leaves can be cut back to just an inch or two above the soil line. In colder climates where freezing is a risk, the rhizomes must be lifted from the soil and allowed to “cure” in a warm, dry location for several days. The cured rhizomes should then be stored for two to three months in a cool, dark environment, ideally between 40 and 60 degrees Fahrenheit. Skipping this rest period is the most common reason for an established Calla Lily failing to produce flowers.
Active Troubleshooting for Stubborn Plants
If environmental conditions and dormancy requirements have been met, a physical or structural issue is likely the cause of bloom failure. One common problem is incorrect planting depth; rhizomes planted deeper than four inches often produce only foliage. For established plants, lifting the rhizome and replanting it closer to the surface can remedy this issue.
Another physical constraint is overcrowding, as Calla Lilies will multiply over time and become root-bound in containers or too dense in the garden. When the plant is actively growing large leaves but no flowers, it indicates a need for division. Dividing the clump every few years and replanting the sections with adequate space will restore its vigor and encourage bud formation. Finally, soft rot, a common disease caused by overly soggy conditions, can stress the plant and prevent flowering, necessitating improved drainage and proper watering practices.