How to prune tansy

Immediately after flowering (mid to late summer); late autumn for full cutback. Remove flower heads before seeds set by cutting stems to just above a leaf. For the mid-season cutback, shear all stems to around 15 cm above the ground. In autumn, cut back to 5–10 cm.

Deadhead after each flush; hard cutback once or twice a year. Tansy is a vigorous spreader that needs firm management. Deadhead immediately after flowering to prevent prolific self-seeding. Cut the whole plant back hard in mid-summer after bloom to encourage fresh foliage growth. In late autumn, cut stems to near ground level. Division every few years controls clump size.

Remove flower heads before seeds set by cutting stems to just above a leaf. For the mid-season cutback, shear all stems to around 15 cm above the ground. In autumn, cut back to 5–10 cm.