Perennials are plants that live for more than two years, returning to grow and bloom each season without needing to be replanted. These plants go dormant during certain times of the year, such as winter, but their root systems remain alive, allowing them to regenerate when the conditions are right. Popular in landscaping due to their longevity, perennials include plants like hostas, daylilies, and peonies. They offer consistent growth and are a cost-effective choice over time compared to annuals.