Monday, August 9, 2010

Indigo Harvest

Today I harvested 1050 grams (2.25 lbs) of Japanese Indigo (Polygonum tinctorium, also known as Persicaria tinctoria). Here is the 2 gallon bucket with the cut stems:

I picked off the leaves into a gallon plastic bag for weighing, then cut them up with kitchen shears:

and stuffed them into a half gallon canning jar and filled it with warm water. Then I put the jar into a canning pot on a hotplate set to heat no higher than 100F to let it ferment overnight:

The next bag (250 g) I put into a 2 1/2 gallon plastic bucket with cold water. I'll add vinegar and macerate by hand to extract the color:

I also have 250g in a yogurt maker with water but it doesn't seem to be heating up much. I should have started with warm water. This is supposed to ferment too. I have just read a recipe for dyeing the fiber right away in the fermented liquid without beating it to oxygenate and then reducing it again. The fermentation splits the indican into indoxyl and glucose with carbon dioxide escaping as bubbles.


  1. I had no idea of this process. I always thought that the indigo color comes from the flowers. Want to see more as you go through this process. I'm so impressed with what you are doing.

  2. Indigo is a unique dye substance. There are many different plants around the world that have the same pigment precursor in them. They all must be extracted in similar ways. People all over figured out how to do this with fermentation vats or mortar and pestal with alkali. I don't know if the method I just used (cold water/vinegar) is traditional; somewhere I read that it was but I haven't seen it mentioned in any of the books I have.

  3. Elizabeth at Strand (url to come...)August 18, 2010 at 5:00 PM

    It's a good thing you're a better gardener than I am, or we'd all be sunk...

    Looks great!

  4. The plants I grow have to be pretty hardy because they don't get coddled, except when they are seedlings. Our volunteer potatoes are doing better than the ones we planted!