In frost-free areas, Calla Lilies will grow in a moist, sunny to semi-shady locations in soil that has been amended with a lot of compost and other amendments such as rock powders and cornmeal products. Plant the rhizomes 3" deep and 12-15" apart. Water liberally and feed monthly during the growing season. After the flowers fade, reduce the amount of water. In areas where Callas are not hardy, allow the plants to dry out. Dig the rhizomes and store in dry material such as sawdust for the winter. Calla lilies are hardy in Zones 9-11.