After flowering is complete, and autumn turns to winter, achillea should be cut back to ground level preferably before the plants go completely dormant and the old flower spikes turn brown. Avoiding wasting energy on setting seeds is just as important in these plants as the more obvious ones like lupins or delphiniums.

Should Achillea be cut back?

They thrive best in a hot, sunny border, where they will quickly fill gaps, and their blooms are attractive to hoverflies. ... Deadhead spent blooms to prolong flowering and either cut back blooms in autumn or leave the seedbeds in situ for the birds. Lift and divide congested clumps every three years, in autumn or spring.

When should you cut back Achillea?

Achillea require no pruning or attention and are generally pest free. In the long term Achillea often runs out of steam after about three to five years, especially on heavier soils. Stocks can be replenished by taking cuttings, pot and grow on in gritty compost until large enough to plant out in the borders.