The calla lily (Zantedeschia aethiopica) is a summer-blooming member of the arum family characterised by waxy green foliage and funnel-shaped flowers that may be white or dark purple depending on variety. Calla lilies are garden favourites, thriving in warm, moist conditions with a little care and maintenance.
All six members of the calla lily genus occur naturally in eastern and southern Africa, growing alongside bodies of water or other areas where wet, waterlogged soils persist. Calla lilies may be grown indoors in bright, indirect sunlight or outdoors in either full sun or light shade. Plants grown in hot climates prefer a location with shifting sun or afternoon shade.
Plant calla lilies 8 to 10 cm (3 to 4 inches) deep, spacing individual rhizomes about 1 to 1 1/1 feet apart. Use a soil that is rich and enhanced generously with organic material such as humus, well-rotted manure and leaf mould. Water frequently, as calla lilies are wetland plants that thrive in moist conditions. Always err on the side of over watering rather than under watering, as calla lilies will even grow in shallow water.
Calla lilies are frost-tender plants that may die in the ground during severe winter freezes. In cooler climates, calla lily rhizomes can be removed from the ground in the fall and stored indoors until the following spring. Dig up the rhizomes once the foliage has wilted, and allow them to dry indoors. Place in a damp, loose potting media such as sterile peat moss, and store at a temperature between 10 and 15.5 degrees.
All parts of the calla lily produce oxalic acid and are highly toxic. The roots are particularly potent. If ingested, symptoms include nausea, diarrhoea, vomiting, swelling and burning of the mouth, tongue and throat, and pain in the eyes. Grazing livestock may ingest calla lilies, leading to poisoning and even death in some instances. Use caution when growing the lily in a household or garden with small children or pets.