Isatis tinctoria

Woad is a European native wildflower, traditionally used as a clothing dye and body paint. The dye is made from the leaves, which are collected from flowering stems and dried in the sun. Once dry, the leaves are ground into paste and left to ferment. The fermented leaves are then moulded into cakes, mixed with water and fermented again. The final step is to infuse the twice-fermented leaves with lime water. The dye is blue and used in place of indigo.

Biennial, woad develops leaf rosettes and deep roots in its first year, and flowers in its second year, before setting seed and dying. Flowers appear in loose racemes, are yellow and develop into large, flat, blue-black seedheads.

Woad is a member of the cabbage family and therefore should be rotated to prevent the build up of diseases, including club root.