Achillea is a summer flowering herbaceous perennial which flowers from June to September. Each flower head comprises hundreds of tiny flowers which are long lasting. Although often referred to by its common name Yarrow, this really refers to Achillea millefolium which is a white variety seen growing wild and illustrated below. The foliage of Achillea is attractive, light, feathered and a little like dill foliage in appearance. The foliage varies in colour from green to grey green, depending on the variety. Because Achillea is herbaceous, it does back over the winter to bare earth.