Cottongrass features showy plumes of white flowers at the ends of the stems in late spring. It's grassy leaves remain green in color throughout the season.Cottongrass is a aquatic perennial with an upright spreading habit of growth. It brings an extremely fine and delicate texture to the garden composition and should be used to full effect.This is a relatively low maintenance aquatic perennial, and is best cleaned up in early spring before it resumes active growth for the season.