How to prune woolly yarrow

Deadhead after flowering (early–midsummer); light trim in late summer or early spring if needed. Snip or shear off spent flower stems at the base of the mat after blooming. If the foliage mat becomes open or untidy, lightly trim it with shears to encourage dense, compact regrowth. Divide overgrown patches in spring.

Deadhead annually after bloom; light trim as needed; rarely needs more. Woolly yarrow (Achillea tomentosa) is a low, mat-forming ground cover that needs minimal pruning. Deadhead spent flower stems after blooming in early summer to keep the mat tidy and prevent self-seeding. Lightly shear the mat in late summer or early spring if it becomes straggly. It rarely needs hard pruning.

Snip or shear off spent flower stems at the base of the mat after blooming. If the foliage mat becomes open or untidy, lightly trim it with shears to encourage dense, compact regrowth. Divide overgrown patches in spring.