The Calla Lily is prized for its elegant, trumpet-shaped flowers and attractive foliage, making it a favorite for garden beds and floral arrangements. Determining its “season” is complex because the timing depends on whether the plant is grown naturally outdoors or commercially cultivated. While native conditions dictate a specific growing cycle, modern horticultural techniques have extended its availability far beyond those natural limits.
The Natural Outdoor Growing Season
Calla Lilies are tender perennials that naturally bloom during the warm season, surviving year-round only in frost-free climates. In their native South African habitat and warmer regions (USDA Hardiness Zones 8 through 10), the rhizomes can be left in the ground to return each year. Their natural blooming period generally spans from late spring through mid-summer, providing a colorful display for six to twelve weeks.
The growth cycle requires specific environmental triggers, primarily the absence of frost and warm soil. Gardeners typically plant the rhizomes in the spring after the last expected frost, waiting until the soil temperature reaches at least 65°F. In colder climates (Zones 7 and below), the plant is treated as an annual since the rhizomes cannot withstand freezing temperatures, but it still adheres to this summer-blooming window. Flowering often peaks in mid-summer before the plant prepares for its off-season rest.
Year-Round Availability Through Commercial Cultivation
Despite their natural summer bloom cycle, Calla Lilies are available as cut flowers throughout the year, a feat achieved by commercial growers. This year-round presence, often seen in wedding bouquets or holiday arrangements, results from carefully controlled greenhouse environments. Growers manipulate the plant’s natural life cycle by providing optimal conditions regardless of the outside season, a process known as forcing.
Commercial production schedules involve managing temperature, light, and water to interrupt the plant’s natural dormancy and induce flowering. By starting rhizomes in specialized conditions, the time from planting to flower emergence can be consistently managed, often taking between eight and fourteen weeks. This allows growers to time harvests for peak demand periods, effectively creating an artificial “season” that aligns with the floral market calendar rather than the sun’s cycle. Controlled light levels and warmer production temperatures ensure rapid development and consistent flower quality.
Ensuring Future Blooms: Post-Season Dormancy
For the rhizomes to successfully bloom again, the plant must undergo a period of dormancy that marks the end of the growing season. As temperatures drop in the fall or after the summer bloom cycle concludes, the foliage naturally starts to yellow and die back. This visual signal indicates that the plant is transferring energy and nutrients down to the underground storage structure.
In cooler regions, gardeners must intervene before the first hard frost to protect the rhizomes, as they cannot survive freezing soil. The process involves gently digging up the rhizomes and allowing them to dry in a cool, well-ventilated area for several days, a step called curing. Once cured, the rhizomes are stored in a cool, dark, and dry place, ideally around 50°F, for two to three months. This ensures they remain dormant and ready for replanting the following spring.