Zantedeschia

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 outside 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 and is a smaller plant (growing up to 16 inches) than the white or yellow flowered varieties. Its leaves are blotched with white or semitransparent spots. The Spotted Calla has white spots on its leaves and white spathes that are faintly purple towards 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 growing in shallow water. They beautiful plants for growing in the water garden.

Pot Cultivation

These plants love moisture and they need to be grown in rich, loamy soil that won't dry out too quickly. They can grow outside year-round in tropical climates; otherwise, they may be brought in during the winter.

The Common Calla and the Spotted Calla - When these Callas are grown in a greenhouse, they should be supplied with a compost of two parts of loam and one part of decayed manure. The dormant rhizomes are potted singly in 5- or 6-inch pots in September and placed in a cold frame where they will form roots if kept moist. Before cold weather sets in, they are set in a greenhouse that has a minimum winter temperature of 50 degrees. They don't need as much water during the winter, but the soil should never become dry. When the flower spathes show, they can be forced to bloom at a higher temperature if necessary. When the flower spathes have faded, you may plant them outside in rich soil, or you may dry them off by gradually lessening the water. The former method is the easiest because once they're in the garden, they need no further attention except to water them in hot, dry weather. If you decide to keep them in pots, they should be given water until the leaves start to turn yellow (since they are deciduous), after which the water supply may be reduced. When they have faded and withered, watering ceases. They may be stored by stacking the pots on their sides on top of each other. Early in September, the plants that were set outside after their spathes had faded, or that were left in their flowerpots should be lifted up and repotted. The old soil should be removed before placing in another pot. A succession of blooms can be accomplished by bringing in a few plants at 2- or 3-week intervals from a cool greenhouse to a warmer one in late winter and early spring. These plants must not be planted outside until all danger of frost is gone. If they are kept in pots, they should be fully exposed to the sun, first in a frame and then outdoors. The Yellow or Golden Calla , Pink Calla and the Black-throated Calla - Their dormant roots can be started into growth from January to March. They're potted separately in 5- or 6-inch pots that are filled with compost consisting of loam and decayed manure, the top of the rhizome should be covered with just enough soil to cover. Keep them moist and warm and they'll soon start to grow. Shade them from very bright sunlight to keep their leaves from wilting and keep their soil moist while they are actively growing. As the flower spathes and leaves begin to fade, gradually diminish the water supply. Once the leaves have fallen, the soil is left to dry. The pots of roots should be stored in a cool greenhouse during the winter. Water the soil only enough to prevent it from becoming bone-dry. From January to March, the roots are taken out of the pots, the soil is removed and they are replanted in rich, loamy soil and restarted into growth. The Pink Calla tubers may be planted individually in pots with a 4-inch diameter.

Aquatic Culture - When these plants are intended for use in the water garden, plant then in 1- or 2-gallon containers filled with rich soil and set in water that is up to 2 inches over the crown. They should have sun or partial shade. In areas where the winters don't produce very hard freezes, the plants will survive outdoors as long as their pots are completely submerged beneath the water; however, the safest way to ensure their survival during the winter is to bring them in a heated greenhouse or under grow lights in the house.