These tender, herbaceous, and aquatic deciduous perennials are native to South Africa. They can be planted in a greenhouse that has a minimum temperature of 50 degrees or outdoors where climates are mild. They are mainly grown for their attractive, large flower spathes, which are usually produced in the spring and summer. Calla Lilies or Arum Lilies, as they are commonly known, are grown in large quantities by commercial growers because they are commonly used for decoration at Easter and throughout the spring and early summer months. Regular gardeners may have them bloom in winter, spring, or early summer, depending on what temperatures are maintained in the greenhouse. The flower spathes of Z. aethiopica, the Calla Lily or Arum Lily, are white tinged with yellow with a yellow spadix, and it produces glossy, arrow-shaped leaves. This variety grows 2 to 3 feet high.
The spathes of the Yellow or Golden Callas, Z. Elliottiana, are yellow. Z. rehmannii, the Pink Calla or Pink Arum, produces lavender-red, rose-red, violet-red, or pink spathes. It is a smaller plant than the other varieties, growing up to 16 inches. Its leaves are blotched with white or semi-transparent spots. The Spotted Calla has white spots on its leaves and white spathes that are faintly purple toward the bases. The Black-Throated Calla has greenish-yellow or pale yellow spathes with noticeable purple-black spots on the bases inside and green leaves spotted with white oblong splotches. Even though these plants are terrestrial, they are moisture loving and can be adapted to grow in shallow water.
According to LaggedyAnne, Calla lilies are poisonous and are traditionally used in bridal bouquets. Thanks, LaggedyAnne, for sharing this! *grin*