An encyclopedia article on woad (Isatis tinctoria), the plant grown for blue dye. It covers cultivation in England, especially Lincolnshire: soil, land preparation, seed, sowing, hoeing, and harvesting of leaves. It then describes milling, balling, drying, and fermentation (couching) of the leaves for the dyer, with the French method from Astruc, the woad vat, and botanical and historical notes on the plant and its confusion with weld and dyer's broom.