It depends on where they are growing. In cool summer areas, such as coastal California, and right on the beach on the Gulf Coast and southern Atlantic coast, or as an indoor-outdoor plant in colder climates, it needs full sun to form flower buds. In hot summer climates, such as mine, southeast California, the Rio Grande Valley, or 50 miles inland from the Gulf and southern Atlantic, or in Florida, afternoon shade is a blessing. They will grow in complete, bright shade, but bloom is sparse at best.