One of the best flowering perennials for sunny sites, echinacea, commonly called coneflower, is a snap to grow. These heat- and drought-resistant beauties develop wave after wave of blooms all summer long. Plus, coneflowers, are a top menu item for hungry butterflies which will flock to your yard to enjoy the nectar-rich blooms. Coneflower colors include pink, red, orange, white, and yellow. Most varieties have large single-petaled blooms. Information is from Costal Farms.