I grew Woad, Isatis tintoria, this year with the high anticipation of extracting the blue dye. I had grown it years ago out of curiosity because the cascade of black seed in its second year of growth fascinated me and I found the seed heads attractive. After playing around with a bit of simple eco dyeing, the prospect of obtaining a blue indigo dye appealed to me. Blue is my favourite colour after all. So far I have learned quite a bit from experimenting and I have quickly learned it will not be as simple as some of my other eco-dyeing. Onion skin and lichen dyes were a breeze by comparison in the past but this requires a little more patience and process.

Woad has been grown in Europe since the Stone Age and along with indigo were the only sources of blue dye widely used. You could call it the original tattoo dye. It was used by the Boudicca and Iceni tribes in the East of Briton to paint their bodies including faces. This body painting supposedly made them look more fierce when in battle. There is an enormous history attached to this plant, not just because of the blue dye but also because of its antiseptic properties. Woad is a biennial and a member of the mustard family. Leaves were apparently harvested in the first year of growth so I thought I would try a few simple ways to extract the blue colour from my few plants. In the plant’s second year it produces yellow flowers resembling a mustard flower, followed by drooping stems of heavy black seeds.

Since harvesting, I have learned it is best to harvest in the prime heat of summer as that is when more pigment is in the leaves. I harvested after a cool spell.

Both these photos are from Susan Dye’s web page, link below.

Unfortunately Woad is now considered an invasive plant in many areas of the United States due to its prolific seed production. The plant emits a substance that is a deterrent to other plants growing close by rather like Spotted Knapweed’s strategy, hence its unpopularity with farmers. I will allow a few of my plants to go to seed next year but they are well contained in a grow tunnel and I would like next year to able to harvest many more leaves.

This year I tried some basic leaf hammering on to premordanted cotton. I also tried hammering the leaves on non mordanted cotton as I read Woad will be colour fast without the mordant. Mordanting is a process whereby the fabric is soaked in a choice of liquids which will render the fibres better able to hold the dye permanently. I wrote about it in previous posts.

When hammering the leaves on to the cotton a very different and quite potent smell is emitted. I am guessing this is what other plants may not like although the other plants in my garden adjacent to this row did not show any ill effects.

I laid some of my leaves down on to the cotton and placed an old sheet over the top. Just by hammering the leaf, you can see the range of green and green blue obtained. I hoped on exposure the green may turn more blue but there has been very little change.

What has been interesting is that I obtained a much clearer blue from my orange, yes orange Daylilies. Above left you can see a pattern of printed orange daylilies and Nigella. On the lower right Woad leaves and Nigella were hammered on to an un mordanted handkerchief.

Now I have learned a few basics I will look forward to trying some more complicated processes next year to extract the blue pigment I am looking for.

If you have not tried eco-dyeing before, I highly recommend this as a fun activity for yourself or children. A mordant is not necessary but the dyes will likely wash out quite quickly. All my photos show fabric that has been washed and rinsed after the processes.