When Avent announced that he was quitting his job to build a specialty nursery, his former horticulture professor begged his student to reconsider, telling him he couldn't possibly make a profit "without doing something illegal." More than ten years and 20 nursery catalogs later, Avent owns a thriving national business with nearly 30 employees. He wrote So You Want to Start a Nursery to debunk myths about the ornamental-plants nursery business and...