Achillea

Plant in spring or autumn in full sun in any well-drained soil. Achillea positively thrives in poor, dry conditions and produces weaker, floppier growth in rich, moist ground. Space plants 45 cm apart. Avoid feeding or enriching the soil — lean conditions keep the plants compact and upright. Water only newly planted specimens during their first summer. Deadhead regularly to promote continuous flowering and to prevent self-seeding, which can be prolific. Divide clumps every two to three years in spring, as they spread quickly via underground runners and can outcompete neighbours. Cut back flower stems that fade to a mid-season brown to refresh the display.

Deadhead spent flower clusters by cutting back to a lower side shoot or to basal foliage. Cut all stems to ground level in late autumn or early spring. The semi-evergreen basal foliage can be tidied in March by removing any dead or damaged leaves.