Outsidepride Bellflower Campanula Glomerata Superba Plant Seed - 2000 Seeds Bellflower Superba grows as a perennial in USDA Zones: 3 - 8 and prefers to be in full sun. Campanula Glomerata reaches a height of 20 inches and has purple blooms in the summer that will attract both butterflies and hummingbirds. These heirloom flowers are perfect for flower gardens and make a wonderful cut flower. Sow at 3 - 4 seeds per plant in well-drained soil and keep moist until germination occurs in 14 - 28 days. Our seeds are always Non-GMO and packaged for the current year.