The calla lily (Zantedeschia) is a popular ornamental plant admired for its elegant, trumpet-shaped blooms and lush foliage. While relatively low-maintenance, its water requirements are specific and change significantly throughout the year, corresponding to its natural growth cycles. Understanding these seasonal shifts is fundamental to successfully cultivating a healthy plant that produces vibrant flowers year after year.
Watering During the Growing Season
The active growth period, typically spanning from spring through late summer, requires the most attention to hydration. During this time, the plant is actively producing leaves and flowers and requires consistent moisture to sustain its high metabolic rate. Water thoroughly when the top one to two inches of soil feel dry to the touch, which often translates to once or twice a week depending on environmental conditions.
Apply water deeply until excess liquid drains freely from the holes at the bottom of the pot. This deep watering technique encourages strong, extensive root systems that support the plant’s foliage and blooms. This approach ensures the entire soil mass is hydrated, not just the surface layer.
Proper drainage is a requirement for calla lilies, even though they tolerate moist environments in the wild. The soil must be well-draining, often achieved by incorporating materials like perlite or vermiculite into the potting mix. Stagnant water around the rhizome, the plant’s underground storage organ, is the primary cause of rot, which can quickly lead to plant failure.
If grown in a container indoors, immediately empty any standing water that collects in the saucer beneath the pot after watering. Allowing the roots to sit in a saturated, anaerobic environment suffocates them and promotes the growth of harmful pathogens. Outdoor plants in hot, dry weather may need water more frequently, possibly every two to three days, as increased temperature and sunlight accelerate evaporation.
Handling the Dormancy Cycle
The calla lily is a perennial that benefits from a distinct period of rest, known as dormancy, usually beginning in late fall or early winter. This resting phase is signaled by the foliage beginning to yellow and die back after the blooming season concludes. Recognizing this cue is important, as it dictates an immediate change in watering habits.
As the leaves start to turn yellow, gradually reduce the frequency of watering. This reduction allows the rhizome to prepare for its rest period by drying out, preventing decay during the winter months. If grown outdoors in mild climates, natural rainfall may suffice, but container plants require careful monitoring.
For the deep rest period, which can last approximately two to three months, watering should cease almost entirely. Keep the soil dry, or nearly dry, to prevent the rhizome from rotting in cool, damp conditions. A plant kept too wet during dormancy will not rest properly and is susceptible to disease.
When new shoots emerge in the spring, signaling the end of the dormancy phase, gradually resume the regular watering schedule. Slowly increasing the moisture level encourages the rhizome to break dormancy and begin its active growth and flowering cycle. This controlled transition helps ensure a healthy start to the new growing season.
Recognizing Signs of Improper Hydration
The calla lily communicates its water status through visible changes in its leaves and stems, allowing for quick diagnosis. Overwatering is a common mistake, often presenting as generalized yellowing (chlorosis) of the lower leaves. Stem tissue may also become soft and mushy near the base, indicating rhizome or root rot due to a lack of oxygen in saturated soil. If you suspect overwatering, stop applying water immediately and ensure the pot and soil have adequate drainage to dry out.
Conversely, underwatering causes the leaves to lose turgor pressure, resulting in a limp, drooping appearance. If prolonged, the edges and tips of the leaves will turn brown, dry, and crispy as the tissue dies from dehydration. The soil may visibly shrink and pull away from the edges of the pot, confirming dryness. Correcting severe underwatering requires a thorough soaking, often achieved by placing the pot in a tray of water to allow the soil to absorb moisture from the bottom up.