Perennials are a flower garden's backbone, providing beautiful color, texture and form. They are easy-care, dependable performers that come back every year. They are also colorful thanks to their foliage and/or flowers. The best times for planting perennial flowers are during the spring and fall. Planting during these seasons will ensure your plants grow healthy and strong. In the spring, you have warmer soil, plenty of rainfall, and longer days with more sunlight. Planting in the fall also has its advantages.