Achillea prefer well-drained soil and can suffer during very wet winters. To protect plants that are susceptible to rot in wet winter conditions, ensure they are planted in well-draining soil and consider adding grit or sand to the surrounding planting area to improve drainage. Raise beds or plant in containers if necessary, and avoid spots where water collects. If wet conditions are unavoidable, consider using a cloche or cold frame to shield the plants from excessive moisture. In exposed positions stake using bamboo canes or brushwood before the flowers appear. Cut down to the ground in late winter, but resist the urge to do this earlier, as the seed heads offer a food source for birds and are attractive in low winter light. Lift and divide large clumps in late autumn or early spring.