BIENNIAL. Ht 60-80 cm.
Also known as dyer's woad, dyer's weed, glastum and Asp of Jerusalem.
This plant produces a mass of yellow flowers on tall stems in early summer, followed by brown seed heads in late summer. The flowers are a magnet for bees and butterflies.
Since ancient times, a blue dye has been obtained from the leaves of this plant.
Plant in any moist soil in full sun.