A native of South Africa, giant calla lilies are often called white giant calla lilies or even Hercules calla lilies, but they are not, in fact a member of the lily family. There are 28 different species of the calla lily, including the wedding favorite, the giant calla lily. The giant calla lily (Zantedeschia aethiopica) differs from the shorter, more colorful varieties of calla lilies. Rather than growing from tubers, as other calla lilies do, the giant white calla lily grows from rhizomes and requires a highly moist environment in which to thrive. Besides its fantastic height and gorgeous, large flowers, an amazing aspect about the giant white calla lily is that the plant will continue putting out brilliant white, stately blooms year round without a dormancy period. Calla lilies can either be grown in the ground or in large containers.
Select a cooler environment, preferably one where the plant can live below 70 degrees. Giant white calla lilies thrive in cooler, well-lit environments.
To plant by seed, sow seeds in the spring in a seeding flat in well-draining potting soil. Insert seeds to a depth of 0.5 inches and cover with potting soil. Keep the seeding flat in a warm location (80 degrees) and the soil moist. Transfer to larger containers after seedlings sprout.
To plant rhizomes, fill a container with standard well-draining potting soil, which will contain enough nutrients to feed the growing plant. Use a pH soil tester and amend as necessary to ensure the potting mix contains a pH of 5.5 to 6.5.
Bury rhizomes 4 to 6 inches deep, gently firming potting material. Water well, then apply a small amount of fungicide.
Keep soil moist at all times but ensure adequate drainage. Giant calla lilies do well in a semi-aquatic environment, but standing water can lead to fungal and bacterial infections. Fertilize weekly after sprouts appear.