Woolly yarrow

Woolly yarrow is a low, spreading perennial with finely divided, wool-covered gray-green leaves and flat clusters of bright yellow flowers. It makes a close-textured groundcover for sunny, well-drained spaces and flowers from late spring into summer. ## Landscape use and appearance Use it along paths, at the front of a border, between stepping stones, or in rock and gravel gardens. Its mat-forming foliage stays low, while the flower stems rise above the leaves. The leaves are soft and aromatic when crushed. Bees and butterflies visit the flowers. ## Size and siting North Carolina State Extension reports plants about 6–8 inches tall and 8–18 inches wide; the RHS lists a broader mature range of 0.1–0.5 m in both directions. Plant in full sun and allow room for the mat to spread. The species is listed for USDA Zones 3–7. ## Soil and seasonal interest Choose sandy, loamy, or shallow rocky soil with good drainage; the species tolerates occasional dryness. Small yellow flower clusters appear from spring into summer, with timing shifting by climate. The fine, gray-green leaves provide a contrasting ground layer around larger flowering perennials. Sources: [NC State Extension](https://plants.ces.ncsu.edu/plants/achillea-tomentosa/) and [RHS](https://www.rhs.org.uk/plants/318/achillea-tomentosa/details). ## Maintenance NC State Extension recommends deadheading after flowering to reduce unwanted spread and possibly encourage more blooms; cutting back to basal leaves may tidy the plant and encourage a later flush. It also advises dividing as needed to control size. The RHS says pruning is not required, so treat this as optional management for self-seeding, appearance, or rebloom rather than a fixed pruning schedule.