2nd Year Maturity. Clips Series White seeds grow year-round campanulas in your home or garden for perennial perfumes. Often planted as annuals, campanula seeds are perennials that grow to be cool-hardy and thrive in a wide range of temperate North American climates. Clips Series White campanula seeds grow compact, yet durable 8-10 inch tall mounds of alpine white ideal for indoors, hanging baskets, or as a potted gift.