Description
Introduction to Calla Lilies
Calla lilies, also known as Arum Lilies (Zantedeschia hybrids), are tuberous perennials that form clumps. They belong to the Araceae family and are native to South Africa, thriving from Tasmania to Queensland. Calla Lilies come in a vast range of hybrids with fabulous colours from pale yellows and pinks to deep burgundy and multi-toned varieties. They tolerate a wide range of climates, thriving in full sun to part shade locations in the garden, but they dislike frost. They require at least 6 hours of sunlight to bloom; more shade will result in more foliage but fewer flowers.
Climate Zones
In regions with hot summers, Calla Lilies benefit from partial shade. They thrive in locations that receive morning sun and afternoon shade, especially to protect them from intense midday heat. Ensure the soil is well-drained to prevent waterlogging, which can cause rhizome rot.
In cooler climates, Calla Lilies can tolerate more sunlight but still prefer partial shade, especially in areas with hot summers. They appreciate protection from the intense afternoon sun to prevent leaf scorch. Well-drained soil is also essential to prevent waterlogged conditions during wetter periods. Also, it is important to keep Calla Lilies consistently moist during summer to prevent them from drying out, which can induce dormancy.
In spring, sturdy stems with large, upward-facing arrowhead-shaped green leaves (some varieties are spotted white) begin to emerge, depending on the climate. Trumpet-shaped flowers appear in late spring in warmer climates or summer in cooler regions, with typically 3 to 7 flowers per rhizome, more depending on size.
Fertilising Calla Lilies
Begin fertilising Calla Lilies in early spring as new growth emerges, and continue through late summer or early fall. Use a balanced fertiliser formulated for flowering plants or bulbs, or a general-purpose fertiliser suitable for flowers. Apply as directed, spreading evenly around the base while avoiding contact with foliage and rhizomes. Water thoroughly after fertilising.
During the growing season, fertilise every 4-6 weeks to support blooms without promoting excessive foliage growth. Cease fertilisation in late summer to allow the plant to enter dormancy naturally, then resume in spring to encourage renewed growth and vibrant blooms.
Dividing Calla Lilies
Calla Lilies should be divided every three to four years in early spring, ideally after the last frost date in your area. This period marks the start of new and active growth for the plant. It’s also the perfect time for tasks such as dividing overcrowded clumps, replanting or transplanting, and amending the soil as needed. When dividing a large rhizome, cut it into smaller sections, ensuring each section has at least one developing eye or bud. These steps ensure that calla lilies have the best conditions to establish themselves and flourish throughout the growing season.
Growing Companions for Calla Lilies
Calla Lilies can be successfully planted with other flowers, but are happiest on their own. These can often enhance mixed garden beds or container arrangements. Good companions include hostas, ferns, astilbes, and other moisture-loving, shade-tolerant plants. Ensure adequate spacing between Calla Lilies and other plants to promote proper air circulation and prevent overcrowding, which can lead to disease.
Growing Calla Lilies in Pots
Calla Lilies thrive in pots and containers, both indoors and outdoors. When planting, ensure each bulb has enough space to grow; ideally, no more than three bulbs should be placed in a 12-inch pot to prevent overcrowding and promote healthy growth.
In cooler climates during winter, it’s crucial to protect potted Calla Lilies from frost and cold temperatures. Move them indoors to a cool, dark location such as a garage or shed where the temperature remains between 4 and 10ºC (39 to 50ºF). This helps keep the bulbs dormant and safe from freezing.
Check the moisture level of the soil regularly, watering lightly if it dries out completely, but avoid overwatering to prevent waterlogged conditions.
During summer, relocate the pots outdoors to a spot with full sun in cooler climates, or partial shade in warmer regions. This ensures they receive sufficient sunlight without risking leaf burn.
For regions where frost is mild or unlikely, you can leave the pots outdoors in a sheltered area. Provide additional protection during frosty periods by covering the pots with a frost cloth or placing them against a south-facing wall that absorbs and radiates heat during the day.
Calla lilies generally bloom within 8 to 16 weeks after planting, depending on various factors such as the amount of sunlight they receive, soil conditions, and climate. When planted in pots, the timing of blooming can be influenced by the size of the bulb, the quality of the soil, and the care provided, including fertilization and watering. In garden beds, they tend to bloom around late spring or early summer, provided they receive adequate sunlight and are planted in well-drained soil.
For cut flowers, harvest from the base of the plant just as they flower, before pollen shedding, to prolong their vase life in bouquets.
Managing Pests and Diseases
Beware of slugs and snails as they can damage the leaves by feeding on them. Regularly inspect your plants for signs of infestation. Use insecticidal soap or neem oil to treat aphids and spider mites, and set up traps or use organic slug pellets to control slugs and snails. Maintaining good garden hygiene by removing debris and dead leaves can also help prevent pest problems. If infestations are severe, consider introducing beneficial insects like ladybugs to help control aphid populations naturally. These strategies are effective across various Australian climates, ensuring your Calla Lily remains healthy and vibrant.
Summary
Calla Lilies
Caution: Harmful if eaten; may cause skin and eye irritation.