The Calla Lily (Zantedeschia) is prized for its elegant, spathe-like blooms and lush foliage, making it a favored houseplant. Originating from the marshy regions of South Africa, these plants grow from thick, underground rhizomes or tubers. Successfully growing a Calla Lily indoors requires understanding its specific needs. This guide provides steps to keep this distinctive plant thriving throughout the year.
Establishing the Optimal Environment
Calla lilies perform best in bright, indirect light for several hours each day. An east-facing window provides gentle morning sun, while a south-facing window requires setting the plant back a few feet to avoid intense afternoon rays. Direct, unfiltered sunlight can quickly scorch the delicate leaves, resulting in brown, crispy edges.
Inadequate light prevents the plant from developing flowers, signaling insufficient energy production. A lack of light also leads to leggy, weak growth as the plant stretches to find a source. Consistent illumination supports the high energy demands of flowering and maintaining deep green foliage.
Maintain a stable temperature between 60 and 75°F (16–24°C) during the day to support active growth. Keep the plant away from cold drafts or drying air from heating vents. Calla lilies prefer moderate to high humidity, reflecting their marshy origins. Placing the pot on a tray filled with pebbles and water can passively increase the moisture surrounding the foliage.
Watering and Soil Requirements
The Calla Lily is known for being a thirsty plant during its active growing season, but careful attention to moisture levels is necessary to prevent fungal issues. When the plant is actively producing new leaves and flowers, maintain consistently moist soil without allowing it to become waterlogged. Allow the top one to two inches of the potting medium to dry out completely before watering thoroughly again.
Proper drainage is necessary to prevent the rhizome from sitting in stagnant water, which is the primary cause of root rot. Always use a container with adequate drainage holes, and empty any saucer or cachepot promptly after watering. Root rot manifests as yellowing leaves and soft, mushy rhizomes due to anaerobic conditions.
A high-quality, well-draining yet moisture-retentive potting mix provides the best foundation for a healthy plant. A suitable blend can be created by mixing standard indoor potting soil with amendments like perlite, coarse sand, or peat moss to improve aeration. The substrate should be rich in organic matter to supply nutrients while still allowing excess water to pass through freely.
The plant benefits from regular feeding during the spring and summer growing months. Apply a balanced liquid houseplant fertilizer once per month, diluted to half the strength recommended on the product label. Over-fertilizing can lead to a buildup of salts in the soil, which can burn the roots and damage the sensitive rhizome.
Managing the Dormancy Cycle
Successfully maintaining a Calla Lily for multiple seasons requires respecting its natural dormancy cycle, which is a period of rest necessary for reblooming. After the flowering period concludes, usually in late fall or early winter, the plant must be allowed to store energy back into its rhizome. Without this necessary rest, the plant will likely fail to produce flowers the following season, instead only producing foliage.
The process of inducing dormancy begins naturally as the daylight hours shorten and the foliage starts to yellow and wilt. When this occurs, gradually reduce the frequency of watering and completely cease all fertilization. This reduction in resources signals to the plant that it is time to slow down metabolic activity and begin preparing for its resting phase.
Once all the leaves have turned yellow and died back naturally, trim the stems down to about an inch above the soil line. Move the pot containing the dormant rhizome to a cool, dark location, such as a basement or closet. An ideal storage temperature is 50 to 60°F (10–16°C) to ensure the rhizome remains cool but does not freeze.
During the two to three months of dormancy, the rhizome requires minimal attention and almost no water. Check the soil occasionally, perhaps once a month, and provide just enough water to prevent the rhizome from completely drying out and shriveling. The goal is to keep the rhizome plump and viable without encouraging any new growth.
After the resting period has completed, typically around mid-to-late winter, prompt the rhizome back into active growth. Move the pot back to its bright, indirect light location and resume a regular watering schedule. This change in environment and moisture signals the start of a new growing cycle, encouraging the plant to sprout fresh foliage and eventually produce new blooms.
Addressing Common Pests and Diseases
Indoor Calla Lilies can occasionally host common houseplant pests, including aphids, spider mites, and fungus gnats. Aphids cluster on new growth, while spider mites leave fine webbing and stippling damage on the leaves. Immediate action is needed to prevent infestations from spreading and weakening the plant.
Minor infestations can be controlled by wiping the foliage with soapy water or applying horticultural oil, such as neem oil. Fungus gnats signal overly moist soil; allowing the top layer of the potting mix to dry out between waterings often eliminates them. Prevent fungal diseases like root rot through careful watering practices and adequate air circulation.