Woad Season 2019

My first season with woad growing and extracting is almost over, so I would like to make a little resume. I hope you will find it helpful :)

Just a little reminder - this is not a manual, just a short report from my experiences.

First of all - if you are historical reenactor or only fascinated in the past dyeing techniques, and hesitate if you should even start playing with woad... do not wait longer, just go for it! It is really not difficult, and really, REALLY satisfying. And I am writing this as a person who killed several plants before (even herbs in pots).

What you need to succesfully grow the woad, is just a bit of land, really not big - you can see a size of my woad 'field' at the photo, it is approximately 3.3 ft (1 m) wide and 6.5 ft long (2 m).

I have managed to grow there about 40 plants, which gave me about 1.5 - 2 kg leaves in one crop. Woad seeds are easy to get, sold in plenty of online shops with natural dyes, wild plant seeds, etc. or even on e-bay. Growing is relatively easy, the main enemies are slugs and snails, which can be deterred for example with crushed shells scattered around. I sow my seeds in May, but next year I am going to do it earlier, even in March, to enjoy bigger number of crops - yes, woad is a cool plant which regrows quite fast, and you can have several crops during one year. I have managed to collect 3 so far, probably will manage once more before first frosts.

In theory you should collect leaves after 10 weeks, I have done it slightly earlier. I wanted to try as many dye extraction techniques as possible, so during the season I have tried making woad balls and pigment extraction with baking soda, lime and soda ash.

Woad balls

This form of preserving woad leaves was very popular during Medieval, as it could be stored for very long time - even years (fresh leaves needed to be used immediately after harvest).

First I needed to harvest the leaves. I decided to start it during one the hottest day in the UK history - horrible weather for people, but apparently perfect for woad (contain of indigo precursor is higher during hot spells).

When I have picked up leaves, I torn them in pieces by hand, throwing stalks away (they did not contain a lot of pigment). Then I put my woad on quern (very primitive, from old paving slab and a brick ;) and started to smash it.

This was exhausting! My arms ached for two days. I pressed out as much of liquid as possible, and from what was left I formed balls. I made four - yes, just four from about twenty plants!

After that I have dried it several weeks, and inside the mysterious process of fermentation was happening. In between they shrank a lot and lost weight as well.

When I had some time off, I decided to try dyeing with one of my woad balls. The big dilemma was which method to choose. Of course I was the most tempted by a fermentation vat - as this one is the most appropriate for the Early Medieval time. But as I am not very experienced with fermentation method, I finally chickened out and decided to try spectralite vat instead, as I primarly wanted to check if woad balls were working, not to reenact the whole process.

I have used the smallest ball, which was slightly mouldy - I was wondering if this would affect the process. It weighted 25 g and I was going to dye 100 g of yarn. I was not sure about ratio, as I could not find guidelines for proportions anywhere - so just decided to try, hoping it will work :) First I have crushed it with a mallet.

When dyeing, I have followed guidelines of Jenny Dean. And if you are going to dye with woad balls it is really worth to read her blog entry carefully, as the vat looks totally different than the one from powdered pigment. First the liquid is brown like a strong tea, then after introducing oxygen turns into green-brown mud, and when finally removing oxygen, is opaque, yellowy-green.

The dyed yarn first was turquise in colour, but the green hue changed and now I have pale blue.

The pigment extraction

To extract pigment from woad I have followed guidelines from woad.org.uk . I found them the most helpful and in general stuck to them. The only thing which I changed was a kind of alkali. So far I have used:

- kitchen soda (sodium hydrogen carbonate) 
- lime (calcium hydroxide)
- soda ash (sodium carbonate)

Every time I have used the same amount of woad leaves (about 1 kg)

Kitchen soda was not a good idea, I used a ton of it but it was not strong enough to raise pH up to 9. I have received some pigment which was quite pale and not a best quality, but it appeared to be good enough to dye woolen yarn (I got nice light blue).


Lime appeared to be a disaster, I was no sure about the amount, so I tried to receive pH 9, and used couple of tablespoons for that. I got no pigment at all, so I have experimented further. I was no sure if I have added to much or not enough and first was adding more lime - still not working - then diluted vinegar, and it finally worked. I have ended with a small amount (1 g) of poor quality pigment (top one on the photo).

Soda ash appeared to work better, I have added only enough to receive pH 9 (3 teaspoons), and soon after aerating a nice dark pigment started to settle down. After couple of hours remained liquid was still blue, but I decided to wash and dry pigment anyway. I got 4 g, and I am pretty happy about it (bottom one on the photo).

What else I can add? I LOVE the woad - not only colours, but also the whole growing and extraction part. I am looking forward to 2020 season, and I am going to grow as many woad plants as possible!

P.S. I am going to perform some experiments with fermentation and set up a little vat even this autumn, when this one will be ready I am going to fulfill this note :)


  • @Annie – happy the note was helpful! Everything alkaline should be fine, but as I wrote, I found the soda ash the best option, so it is a good choice. I have tried a fermentation vat twice – once with urine (smell better than I expected and amazing colours!) and second time with bran and madder – more about it you can read here: https://medieval-colours.co.uk/blogs/news/medieval-woad-vat-experiment-with-fermentation
    Cheers :)

  • Hi Katarzyna – This was so good to read, as I’m on a similar adventure and have had varying success with extracting pigment. I’ll try the soda ash instead of Calcium Hydroxide and would love to know if you did try a fermentation vat. I’m going to have a go with bananas! Annie ☺️


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