Look out for this yarrow! This is the common yarrow, native to Europe and western Asia. It is not as well behaved as all of its more beautiful brethren with lovely colored flowers, but this is the best yarrow for medicinal uses. Flowers are white, and the plant spreads underground by runners. It will also self-sow joyously, which can be a problem. If you are harvesting your flowers regularly for medicinal use however, you will not have troubles with this one getting away. ‘Proa’ is a selected form that is higher yielding.
If you are trying to get yarrow to naturalize, this is a good choice. It attracts butterflies and beneficial insects, and is a great cut flower both for fresh use and for drying.
Regular watering will promote more growth and flowering, but treating it as a drought tolerant plant will definitely help stop it from becoming invasive.