Pruning Yarrow 'Terracotta'

Achillea 'Terracotta' requires minimal pruning, but a couple of well-timed cuts will keep it tidy and encourage a longer flowering season. The main pruning window falls in August, after the first flush of blooms fades, and again in March as part of the spring tidy-up. Deadheading is the most useful task during the flowering period, which runs from early summer through to late summer. Once the flat flower heads turn brown and lose their colour—usually by mid to late August—cut the spent stems back to just above a set of healthy leaves or a side shoot lower down the stem. This often prompts a second, smaller flush of flowers in early autumn and prevents the plant self-seeding everywhere, which it will do enthusiastically if left to its own devices. In March, before new growth emerges, cut back all the old stems to ground level. Use clean, sharp secateurs or garden shears. The dried stems and seed heads can look attractive through winter, especially when rimed with frost, so many gardeners leave them standing until late winter both for structure and to provide seed for birds. If you prefer a neater look or the stems have collapsed and turned mushy, you can cut back earlier in late autumn, but waiting until March protects the crown from excess winter wet. Yarrow clumps can become congested and flower less freely after three or four years. If this happens, lift and divide the clump in March or April, replanting only the vigorous outer sections and discarding the woody centre.