Weld

Biennial plant forms a low rosette of leaves the first year and a tall stalk with fragrant yellow-green flowers in June the second year. Traditional European source of colorfast bright yellow dyes. Harvest each entire stalk in full bloom when the pigment is most concentrated, and to prevent reseeding.

Weld yellow dyed with woad blue makes Robin Hood's “Lincoln green.” A good source on growing and harvesting weld.