Woad is the indigo bearing plant that was grown in Europe through out the centuries from Roman Times to the 1700’s, when it was replaced in importance by imported Indigofera tinctoria from
Woad is valued for its complex blue shades and for its fastness. Even after Indigofera gained importance, dyers still added woad to the indigo dye vats for its fastness.
Woad was used in
There are more than 30 different varieties of land race Isatis tinctoria (woad) growing today in UK, Europe, and the Middle East. Very little selective breeding has been done.
There are vast differences among the land race varieties in indigo production. and within individual varieties from year to year. Woad increases its indigo production after a period of hot, sunny weather -- harvesting at the peak of summer ensures high dye content in the leaves. Several harvests are possible, as the plant regrows rapidly after harvest. In warm areas up to 5 harvests are possible, annually. In my zone 3 climate, that receives summer frost, 3 harvests are reasonable -- July 1, August 10, September 15.
Commercial dyers also used couched woad imported from Europe, and the working of the woad vat was considered the accomplishment of a Master Dyer.
Although the woad plant contains indigo precursors at every stage of development, the first year rosette has the highest indigo precursor level, and is the part of the plant most commonly used for commercial production.
Very little commercial production of woad-indigo is being done today, however two enterprises are attempting a revival of woad production in UK and EU.
The European woad growers recognized 2 distinct types of Isatis tinctoria. One, which the French called "Pastel," has smooth leaves (microscopic hairs can be seen), high indigo content, and was valuable for cattle fodder, . A second type, which was referred to as "Bastard woad" was contientiously rogued out of the pastel patch. It had coarse, hairy leaves, a low dye content and was unpalatable to livestock.
It is the "Bastard woad" that came to the USA and threatens to overrun Western range land. It began in a 1900 contamination of Alfalfa Seed in Calilfornia, which got away. This is the woad being used today by natural dyers in North America. Its indigo yield is low and the hairy leaves contaminate the dye bath with soil and other impurities which inhibit the extraction of indigo from the leaves.
