Woad a native of the Mediterranean and is closely related to broccoli and cabbage.
During the first year it looks similar to spinach. During the second year it grows to a height of 1.5metres and resembles oilseed rape.
It has been famous as the source of blue dye for thousands of years in Europe and the Middle East. The dye chemical extracted from woad is indigo – the same dye extracted from Indigofera tinctoria, but in a much lower concentration.
Woad is a biennial. The first year the leaves produce the blue dye. The second year after flowering it produces an abundance of seeds, which if allowed to mature and drop, will cause a problem as they will be extremely difficult to control and will take over the site. I place a large bag over the seed heads and cut the stalk and allow them to dry in the bag. I save what I require for the next planting and sell the remainder.
Plant woad seeds 4 inches apart and 2 inches deep in March/April. They do not transplant well so it is preferable to plant them directly into rows and thin them out later to about 12 inches apart.
Woad benefits from an alkaline soil. Before planting apply garden lime and try to attain a pH of between 7 and 8.
Move your woad crop each year if possible because it is a heavy feeder and depletes the land it grows on of nutrients which is reflected in the depth of colour when the pigment is extracted.
Harvest the leaves about mid July by cutting off the outside leaves with seceters, leaving the crown in the centre. The woad plant will grow new leaves from the crown and can be harvested again in about another 6 weeks.
We sell woad pigments and seeds at The Beehive Shop and online at www.dyeing-crafts.co.uk