After flowering shear back the plants and they will form a dense mat of foliage. If they start dying out in the center remove some of the healthier outside clumps and replant.
Propagation
easy by division, seeds
Native Site
Native to Europe and Western Asia and considered to be a weed in many areas.
Misc Facts
Achillea honours for some authorities a hero of Greek mythology Achilles. Millefolium is derived from Latin mille- (thousand) and -folia (leaved) components meaning ‘many leaved’. (www.plantlives.com)