Eupatorium cannabinum 

Europe, Caucasus, Central Asia. Hemp Agrimony from moist stream banks and the like. However adaptable to the garden.  Stems are a deep reddish colour and are topped with pale pink clusters of flowers loved by bees and butterflies. It an be used formally or informally in perennial borders, wildflower gardens, or naturalized landscapes. Being a bit shorter it will work well with the taller Joe Pye weed or in smaller spaces. Summer to autumn flowering. 130cm 

Small, strong plants so easy to freight, but only a few. 

Amazing flower head image: ReneeWrites, CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons

GT1976, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons