Dyeing with Woad Seed
Updated: Jun 22
If you have ever grown Woad for dyeing blue with the leaves, you will know that there are an awful lot of seeds produced as well. In fact, far more than you will ever need or be able to give away.
Woad is a 2 year plant. The first year it looks like a spinach plant, with a neat crown of leaves. I have actually grown it in the flower border as foliage because it's quite pretty at that stage. This first year is when you harvest those leaves for the blue dye they contain. But if it is left, it dies back in the Winter and reappears in Spring, sending up quite a tall shoot perhaps as high as four feet. During this second year of growth there is no blue dye-value in the leaves. After the yellow flowers the seeds will appear, hanging down in clusters.
If you are after the seeds for dyeing then wait until they are fully ripe and black before harvesting. As the plant has no dye value at all at this point, I would pull it up, and hanging it in an airy place to dry. The seeds could be stripped straight off at this point, but I prefer to make doubly sure there's no moisture in them at all, so I hang plants for a few weeks under cover. If you are going to dye with the seeds straight away then you can skip this drying out stage. The plants are quite large, and take up a fair amount of room so maybe those with limited space will have to improvise and perhaps cut off the seed clusters and dry them in bundles.
My first experiment in Woad Seed dyeing was a flop. Basically I just got brown. So I put the seeds into a big screw top jar, and left them there. For five years. Yes..
Just a quick word about the seed harvest, make sure they are dark and fully ripe. You will see green and quite pale seeds. They have little value in them, so leave them on the plant to ripen up. I'm holding some unripe seeds over a dish of ripe seeds in the next pic just so you can see the difference.
Recently was having a de-clutter time and took some jars of seeds to the compost bin, and began to pour..then stopped..and thought 'why not'. So back into the dye-kitchen with them. I wasn't sure what dye-value there would be after five years. The dye-pot was very concentrated. I literally poured every jar of seed into the pan, and filled with water and cooked it for an hour. Then I strained the liquid off, (it was a very dark sherry colour), and repeated with fresh water. My resulting dye bath looked..brown.
I dip-dyed some sections of yarn I was working on, and got...brown. A nice brown. But, it wasn't pink as I had hoped.
I always squeeze as much dye out of one pot as possible by using up waste dye-baths, and having some handspun Clun Forest yarn to hand (which had been pre-mordanted in Alum/Cream of Tartar), I decided to dip dye part of the skein into it.
The yarn had been sitting over night unintentionally in a weak vinegar rinse. I took it straight from there to the dye-pot without thinking. Later when passing by to get something from the kitchen I stopped dead in my tracks as I could see the amazing lavendar-purply-pink creeping up the wet skein. Really magical! As this was on previously undyed white wool, the result was, for me, quite dramatic.
It needs to be said here that this was the waste or second dye bath. Had I achieved this result with the first one, the pinks would have been even darker.
My first dye-bath was used to over dip-dye these previous dyed Teeswater locks (previously dyed with Logwood and Madder root). It gave them a deeper purple and a lovely hue on the ends.
Having a second dye-pot containing the same solution, I added a really tiny weeny (I mean less than a quarter teaspoon) bit of dissolved iron. The pot turned quite dark, as would be expected with iron. But when later dip-dying another part of the skein in it, I still got the pinky purple colour, only slightly darker. The other pale salmon pink in this skein is achieved with a waste Avacado pit dye solution.
So the addition of vinegar to the dye-bath is the essential part in trying to get pinks rather than browns. It pushes the whole dye-bath into a more acidic state by lowering the ph. There was very little vinegar in my dye-bath, perhaps only a spoonful.
Don't be put-off by the colour of the dye-bath. It will be brown even if it produces pink on the wool. Also, there is a surprising amount of dye in what looks like a pot of liquid that might get thrown away, so even if you have had 2 lots of dyed wool from your dye-pot, just have another go and see if you can get something out of the third because likely there will still be something in there!
And finally, the great thing about Woad Seed is, it will keep! Woad as a blue-leaf-dye needs to be used fresh, and only during the first year, and usually during the Summer months. So the window of time for using it as a dye plant is quite small. But the seed will save for years and years. A great harvest for a rainy day!