3 Simple Tips for Optimal Perennial Garden Care everyone needs to understand. SPRING and FALL are Crucial for the Success of your garden. What even is a Perennial Garden?? Simply put, unlike annuals or biennials, perennials are plants that live year after year. Some perennials, such as trees and shrubs, have significant life spans. Others, like many flowering perennials, may need to be replaced every three or more years. This video takes you through the basics with Spring and Fall Maintenance!