The Calla Lily (Zantedeschia aethiopica and its hybrids) is a beloved plant known for its elegant form. Its signature structure is not a true flower, but rather a large, flaring leaf-like structure called a spathe that wraps around a central spike, the spadix. This South African native is popular as a sophisticated indoor specimen and a striking perennial in mild outdoor garden settings. Successful year-round care depends on understanding its environmental preferences and seasonal needs.
Establishing the Ideal Environment
Calla Lilies thrive in bright, indirect light when grown indoors near a sunny window. Placing them in direct, unfiltered sun for extended periods, especially during hot afternoons, can cause the delicate leaf margins to scorch and brown. When situated outdoors, they prefer a location that receives partial morning sun and shade during the intense mid-day heat. Insufficient light exposure will often prevent the plant from blooming and lead to weak, leggy growth.
Maintaining a consistent temperature range is beneficial for healthy growth. The ideal daytime temperature for active growth is between 60°F and 75°F (15°C to 24°C). Nighttime temperatures should ideally not drop below 50°F (10°C) during the growing season to maintain vigor. The plants are highly sensitive to frost, meaning temperatures below 32°F (0°C) will damage the rhizomes and foliage, requiring careful winter protection.
The planting medium should be rich in organic matter but possess excellent drainage to prevent root rot. If planting in a container, ensure it has multiple drainage holes, as the rhizomes are susceptible to over-saturation. Clay or terracotta pots can sometimes help wick away excess moisture from the soil. A slightly acidic soil pH, typically between 6.0 and 6.5, supports optimal nutrient uptake and overall plant health.
Routine Hydration and Feeding
Although Calla Lilies are thirsty plants, managing moisture levels is necessary to avoid rhizome decay. During the active growing season (spring and summer), water the plant deeply until the excess liquid runs from the drainage holes. Allowing the soil to become overly saturated is the most common cause of plant failure. The soil should then be allowed to dry out slightly before the next watering, specifically letting the top one to two inches of the potting mix become dry to the touch.
Outdoor plants in hot, dry conditions may require more frequent watering than indoor counterparts. Using distilled or rainwater is recommended if tap water contains high levels of chlorine or mineral salts, which can accumulate in the soil. Consistent moisture is necessary for the plant to produce lush foliage and flowers.
To support the production of foliage and spathes, a consistent feeding schedule is necessary during the growth phase. Use a balanced, liquid fertilizer high in phosphorus, such as a 10-20-10 formulation, to promote blooming over leaf growth. Apply the diluted fertilizer every two to four weeks, starting when new growth appears in the spring.
Directing the plant’s energy toward new blooms is achieved through maintenance pruning. Once a spathe begins to fade or turn brown, remove it (deadheading) by cutting the stem near the base of the plant. Similarly, cleanly trim away any leaves that turn yellow or look damaged to improve air circulation and aesthetics. Cease all fertilization immediately after the plant stops blooming in late summer to prepare it for its rest period.
Handling Dormancy and Storage
Calla Lilies require a period of rest, or dormancy, to conserve energy and ensure reblooming. As the days shorten in late summer or early fall, the foliage will naturally begin to yellow and wilt. This signals the time to gradually reduce watering and completely stop fertilization. Continued watering at this stage encourages rot.
Allow the soil to dry completely once the foliage has collapsed. If the plant is grown outdoors in a climate where the ground freezes, the rhizomes must be lifted from the soil before the first hard frost. Brush the excess soil off the rhizomes and store them in a cool, dark, and dry location, such as a basement, where temperatures remain consistently above 40°F (4°C). Proper ventilation prevents fungal growth during this resting phase.
In early spring, about eight to ten weeks before the last expected frost, inspect the stored rhizomes for decay before repotting or replanting. Immediately begin a light watering schedule once the rhizomes are back in the soil. This encourages the emergence of new shoots, signaling the start of the next growing cycle.