Calla lilies are elegant plants, admired for their unique, trumpet-shaped blooms. These striking structures, often mistaken for petals, are modified leaves (spathes) unfurling around a central spadix. Their graceful form and wide array of colors make them popular for gardens and floral arrangements.
Understanding Calla Lilies
Calla lilies, botanically Zantedeschia, are not true lilies but belong to the Araceae family, related to philodendrons and peace lilies. Originating from Southern Africa, they thrive in marshy, damp environments. Growing from thick, fleshy rhizomes, they are herbaceous or semi-evergreen perennials. Zantedeschia offers diverse spathe colors, including white, pink, yellow, purple, and nearly black, often with speckled foliage. They symbolize purity, resurrection, and beauty, making them popular in bouquets and religious observances.
Planting Your Calla Lilies
Proper planting is key for calla lilies, whether in garden beds or containers. Outdoors, choose full sun in cooler climates or partial shade in hotter regions to protect from intense afternoon heat. Soil should be organically rich, moist, and well-draining to prevent rhizome rot. Amend heavy clay soils with compost to improve drainage.
Plant rhizomes in spring after frost danger, when soil warms to at least 65°F (18°C). Bury rhizomes 3 to 4 inches deep, with growing tips facing upwards. Space rhizomes 6 inches apart in garden beds, or 4 inches apart in containers for a fuller display. After planting, water sparingly until shoots appear (typically within two weeks), then increase watering as plants establish. For containers, use quality potting mix and ensure adequate drainage holes.
Ongoing Calla Lily Care
Light Requirements
Calla lilies thrive in bright, indirect light, with needs varying by climate. In cooler areas, full sun encourages abundant, vibrant blooms. In hot regions, partial shade during afternoon hours prevents leaf scorch and maintains health. Indoors, place near a sunny window receiving at least six hours of bright, indirect light daily. Insufficient light causes leggy growth and reduced flowering; excessive direct sun can burn foliage.
Watering Practices
Consistent moisture is important, but avoid soggy conditions to prevent root rot. Once established, water thoroughly, allowing the top inch or two of soil to dry slightly between waterings. This keeps soil moist without waterlogging. Indoor plants may need more frequent watering due to faster soil drying. Room-temperature, filtered, or rainwater is beneficial, as they can be sensitive to tap water chemicals.
Soil and Nutrients
Well-draining, organically rich soil is best for healthy growth. Though they appreciate consistent moisture, rhizomes rot in poorly draining, heavy soils. Incorporate compost or organic amendments before planting to enhance nutrition and improve drainage. During the active growing season, regular fertilization benefits calla lilies. Apply a balanced liquid fertilizer (e.g., 10-10-10 or 20-20-20) every two to four weeks, especially for container plants. Over-fertilization, especially with too much nitrogen, promotes foliage over blooms.
Temperature and Humidity
Calla lilies prefer a warm environment, with optimal temperatures from 60-80°F (15.5-27°C). They tolerate some frost, but prolonged exposure below 32°F (0°C) can cause damage. Indoors in winter, 50-60°F (10-15.5°C) can promote future flowering. As tropical plants, calla lilies appreciate high humidity. For indoor plants, maintain humidity by misting leaves, using a pebble tray, or a humidifier. However, excessive humidity with poor air circulation can lead to fungal issues.
Winter Care and Dormancy
Calla lilies are perennials benefiting from a dormant period, especially in cooler climates. In USDA zones 8-10, rhizomes typically remain in the ground over winter. In colder zones (3-7), treat them as annuals or lift rhizomes for winter storage. Foliage yellowing and dying back, usually after the first frost, signals dormancy.
For outdoor plants in cold climates, dig up rhizomes, remove excess soil, and allow them to dry or “cure” in a warm, dry place for several days. Once cured, store rhizomes in a dark, cool location (50-60°F / 10-15.5°C) in slightly damp peat moss or vermiculite. Periodically check rhizomes throughout winter to ensure they are not rotting or shriveling. Container plants can be moved indoors, with watering gradually reduced to encourage dormancy and natural foliage dieback. Then, store them in a cool, dark place without water for two to three months.
Troubleshooting Common Calla Lily Problems
Calla lilies are generally robust, but issues can arise from environmental imbalances. Yellowing leaves (chlorosis) often indicate overwatering or poor drainage, leading to root rot. It can also stem from nutrient deficiencies (e.g., lack of nitrogen), cold temperatures, or insufficient light. Adjusting watering to allow soil to dry slightly between waterings and ensuring proper drainage often resolves this.
Lack of blooms can stem from insufficient light, improper fertilization, or inadequate dormancy. Calla lilies need ample bright light for flowers; too much nitrogen encourages leafy growth over blooms. Ensure adequate light and use a phosphorus-rich fertilizer. Additionally, deep planting or dense soil can inhibit flowering.
Pests like aphids, spider mites, mealybugs, and slugs can affect calla lilies. Aphids and spider mites feed on plant sap, distorting leaves; slugs create holes. Control methods include washing plants with insecticidal soap or neem oil; for slugs, handpicking or barriers are effective.
Fungal diseases like root rot, powdery mildew, and leaf spot are concerns, often exacerbated by overwatering, poor air circulation, or high humidity. Root rot, caused by soggy soil, leads to yellowing leaves and mushy roots. Preventing these issues involves proper drainage, avoiding overhead watering, and good air circulation. Remove affected plant parts; fungicides may be necessary for severe cases.