Achillea are easy to grow and will do well in a sunny position in most well-drained soils, but will not tolerate waterlogged conditions. Water at least once a week during summer months until established, but keep watering in winter to a minimum. Once established Achillea are fairly drought tolerant. Remove spent flowers during the season to encourage more to grow. After flowering is complete, and autumn turns to winter, Achillea should be cut back to ground level preferably before the plants go completely dormant and the old flower spikes turn brown. They can be lifted and divided every three to five years, which will revitalise the original clump and give you new plants to grow elsewhere.