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.
Growing calla lilies from seeds requires a little work and some patience. It can take up to three years for a calla lily planted from seed to bloom. The seeds are often pre-grown in order to be successful. Spread seeds out on a damp paper towel, cover them and put in a cool location. Check the seeds in a few days for growth. Discard any that do not show any signs of life. Put a high-quality potting soil in a well-draining pot and place the seeds that have started in pots or flats. It is best to plant at least two seeds per pot just under the soil surfacer. Keep the soil moist and watch for growth. After a week remove any seeds that have not grown. After a few weeks remove the weakest shoots. This will give energy to the stronger sprouts. Once the plants have grown a while, they can be transplanted into larger pots or transplanted outside. Water the newly transplanted plants regularly until they become established.