This compact, herbaceous perennial has been a mainstay in gardens since it was introduced in the 1950's. Ferny gray-green leaves are topped by flat, yellow flower clusters from mid spring until October. It is tolerant of full sun, extreme heat or cold, and can grow in a variety of soils. Regular water is necessary throughout warmer months, but it will survive cool season drought. Cut back spent flower heads to encourage more blooms. Flowers make great cut flowers or can be preserved by drying. Yarrows are favorites of butterflies, but not so much mammals like bunnies or deer, who find the aromatic foliage distasteful.