|Is there a reason why Yarrow is so hard to come by and certain shades you can't even find? Are they difficult to grow? Are they invasive?|
|There are about 85 species of achillea, but most garden selections have ferny, often feathery foliage and flat umbel flowers, although some, like ?The Pearl? have small button -like blossoms and others have flowers resembling daisies.
Yarrow is easy to grow, tolerant of most growing conditions, but prefers well-drained soil and full sun. Allow for good air circulation to prevent fungal diseases. Plants should be deadheaded for continual bloom. Shearing back after the second bloom will refresh plant and reduce need for staking. Can spread rapidly if happy. Divide every 2-3 years.
If you are having difficulty finding plants, you can order seeds from Park Seed or other companies (online or through catalogs).