How to Prune hemp agrimony?
Cut back spent flowers at end of the flowering season

hemp agrimony · Eupatorium cannabinum
Also known as: ague weed; andurion; bastard agrimony; common hemp agrimony; Dutch agrimony; hemlock parsley; hemp weed; holy rope; Indian ague root; water agrimony; water hemp
Grow in any moist soil in full sun or partial shade. Can spread quickly, but is very attractive to butterflies and other insects
Cut back spent flowers at end of the flowering season