How to prune costmary

After flowering (late summer) for tidying; late autumn or early spring for full cutback. Deadhead spent flower stems by cutting to the base. In late autumn or early spring, cut all stems down to just above soil level. Divide congested clumps every 3–4 years to maintain vigour.

Once or twice a year. Costmary is a vigorous perennial herb that spreads by rhizome more than it needs pruning. Cut back flowered stems after blooming in late summer to encourage fresh basal foliage. Cut the whole plant down to ground level in autumn or early spring to clear old growth and stimulate new aromatic leaves.

Deadhead spent flower stems by cutting to the base. In late autumn or early spring, cut all stems down to just above soil level. Divide congested clumps every 3–4 years to maintain vigour.