Yarrow is a rhizomatous broadleaf weed with finely cut leaves. It can reach 1 meter in height but also thrives in short, dense patches when growing in mowed grass. Its stems are mostly unbranched with fine white hairs or nearly smooth surfaces. Yarrow has a deep and extensive system of rhizomes with fibrous roots and may give off a pungent aroma when its foliage is crushed. Blooming from May through late summer, Yarrow produces small flower heads that have five white ray flowers and a similar number of pale-yellow disk flowers in the center.
This broadleaf weed does best in dry, disturbed areas, including pastures, fields, prairies, unmaintained lawns and along roadsides and railroads. The weed is also cultivated and sold as Yarrow, Milfoil or Bloodwort in nurseries and garden centers. Yarrow thrives throughout most of North America.
Cultural weed control methods are almost totally ineffective for discouraging Achillea millefolium in your lawn. It is nearly impossible to ensure that all of the rhizomes are eliminated if physical removal is attempted, and Yarrow can adapt to different mowing heights. Professionally applied broadleaf weed killers are recommended for complete removal.