We plant flowers to welcome the spring and brighten our receding winter landscapes. We add color to the summer garden and often admire them from the comfort of our air-conditioned home. But the time of year when we step back outside to enjoy the cooler autumn temperatures, our gardens are often left barren. Leaving fall color to only the trees and the mums planted at your front door. Take advantage of the pleasant temperatures and extend your garden palette with these 5 must-have perennials for fall color.