Find out more... about woad

What exactly is woad?

Woad plants, photo by Alpus.

Woad plants, photo by Alpus.

Woad is a plant or herb in the mustard (Brassica) family. In previous centuries it became widespread as a source of blue dye. Its flowers, produced in the summer, are yellow, and the plant grows to just under one metre in height. The Latin name for woad is Isatis tinctoria.

The plant is dried in a special way with natural fermentation to produce balls or cakes for dyeing.

The history of woad

In Iron Age Britain, woad was reportedly used to colour warriors before going to battle. The example of Queen Boudicca or Boadicea of the Iceni tribe adopting woad is widely cited - as a tactic to spread fear among the enemy.

Its use during combat is alternatively attributed to the antiseptic properties of the plant, and indeed woad has been prized since ancient times for its medicinal properties.

There is a theory that the word Britain is derived from the custom of war-painting - holding that the old Celtic term for paint was Brith, while Brithon signified “stained man”.

Hôtel d’Assézat, Toulouse, photo by Pom.

Hôtel d’Assézat, Toulouse, photo by Pom.

During the Renaissance, woad became a mainstay of the regional economy in south-west France and made the fortunes of the city of Toulouse.

In the last ten years, having scoured the city archives, researchers have breathed life back into this almost forgotten treasure. The plant is now being grown as a crop once again, in characteristic yellow fields. A museum has been created, as well as a spa with treatments based on woad, not forgetting the purpose-built dyeing atelier.

What’s the difference between woad and indigo? 


The chemical compound which produces the very special blue colour is called indigotin. A large number of plants can produce indigotin, and have been used to make blue dye across different continents and through the ages. A synthetic version was also developed around one hundred years ago.

Of these blue dye-producing plants, woad corresponds to the plant Isatis tinctoria, and indigo to the plant Indigofera tinctoria.

Confusion sometimes arises when people use the term indigo when they actually mean the pigment indigotin.

Dyeing cloth with woad

One way to dye fabric with woad is to use balls made from dried plants. This method has been revived in Toulouse, in a special dyeing atelier and research centre.

The ball or cocagne is placed in a large basin of water, and when the water takes on a yellow tinge, the cloth is placed in the basin, stirred around, and then removed with tongs. As the air touches the cloth, a beautiful and surprising alchemical change takes place as the yellow turns first green then deeper and deeper blue.

Photo of hands forming cocagnes of woad, © J Scott.

Photo of hands forming cocagnes of woad, © J Scott.