Calla Lilies, also known as Arum lilies, are not true lilies at all but members of the Araceae family. Native to southern and eastern Africa, calla lilies require warm temperatures to survive as perennials. In most areas of the country, gardeners must dig up and remove the tender rhizomes to overwinter indoors. Calla lily rhizomes survive in the ground all year only in USDA Plant Hardiness Zones 9 through 10. Prized for their long-lasting trumpet-shaped blooms and arrow-shaped foliage, calla lilies have become extremely popular as cut flowers. They often appear in flower arrangements, particularly bridal bouquets.
Plant calla lilies during spring after the danger of frost has ended. Choose a location that receives full sun to partial shade and has moist, rich soil. Space calla lilies 12 to 24 inches apart to provide plenty of room as the plants grow.
Water once each week during spring and summer to prevent the soil from drying out completely. Reduce watering frequency to once every two weeks during fall when temperatures begin to drop.
Feed calla lilies once each year immediately after planting the rhizomes. Use a 5-10-5 NPK fertilizer to provide proper nutrition for growth and flowering. Apply at the rate described on the packaging for the best results.
Remove faded flowers and damaged or disease foliage as often as possible to improve the aesthetic appearance and general health of the plant. Pinch off the flowers or leaves at their point of origin to reduce damage.
Use a shovel to dig up calla lily rhizomes during fall after frost has killed all of the foliage. Store the rhizome in peat moss at a temperature of 50 to 55 degrees F until spring. Replant outdoors during mid-spring, after the danger of frost has passed.