Calla lilies prefer full sun and perform well in soil that stays moist. They will bloom in the summer in partial shade, especially when the soil remains evenly wet throughout the season; calla lilies grow well beside a pond or other body of water. The rhizomes, or bulbs, look like small potatoes and grow well when planted about 1 inch deep. Rhizomes should be spaced about 1 to 2 feet apart.