Achillea is an adaptable perennial flower that forms dense, flat flower clusters above green to gray fragrant foliage. Commonly known as Yarrow, Achillea is tolerant of heat, drought and coastal conditions. Most Achillea will also tolerate various soil conditions other than heavy, wet soil and dense clay. This long-bloomer is attractive to butterflies and pollinators, flowering from summer to early fall. Deadheading will encourage more flowering.