This is the larger and louder American cousin of our native vervain, also used as a nervine and a long-term tonic for anxiety and stress-related disorders.
Whilst this blue vervain has similar therapeutic activity to its European relative Verbena officinalis, it looks quite different. Its magenta-blue flowers grow to eye height by mid-Summer, luring the eyes and bees towards them.
Blue vervain is a perennial that flowers in its second year of growth. In full bloom it can grow up to 2m, and when fully laden with flowers it can topple over under its weight, so it is best grown amongst sturdy companions to provide support. It grows best in full sunshine, and prefers relatively moist, loamy or sandy soil. Harvest the aerial parts as soon as it comes into flower.