Wednesday, 18 July 2012

Growing Polygonum tictorium (Japanese Indigo)

There are a few dozen different plants that contain the indigo pigment. The primary indigo plant in Japan is Polygonum tictorium. I've grown three varieties of this over the years. A round leaf version. A white flower version and the regular pink flower version. There is a close relative that grows just about everywhere around here that has almost no blue pigment . Growing them in close proximity to each other they cross pollinate and I've ended up with round leaf pink and white flowers and once some very weak pigmented indigo amongst the good stuff. If you are in Japan and there is natural tade indigo around your field weed it out before it flowers and messes up your seed stock. Here is a picture of the natural no pigment indigo next to some healthy indigo in my compost box. The thinner  paler leaf in the back is the bad stuff.

The Japanese indigo looks a bit like basil. Here is a picture of basil in my indigo garden. The basil is in the middle.


The rainy season is almost over and it was 35 degrees for two days. The indigo is ready for the first harvest size-wise. I checked the pigment content by picking a few leaves and drying them in the sun to see what color they became when dried. The leaves did not turn a dark blue color. They need a week or so more of strong sunlight and ultra-violet rays to produce more pigment. If you are lucky you only get 5% weight of the leaf in pigment with Japanese indigo. Make sure you harvest at the right time or you end up with very little dyeing power.



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7 comments:

  1. onesmallstitch18 July 2012 at 09:43

    thanks for the tips, I had to run outside and check my plants - but of course I know where the seeds came from! Not much luck with sun, we're lucky if the temp. hits 20. guess I can be thankful if I just get seeds this year.

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    1. Bryan's Japanese Textiles18 July 2012 at 20:32

      You know, besides my compost box monster indigo plants, Ogata san has won hands down again. Her row at her place is a good ten centimeters higher than 'our' rows.
      b

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  2. Leena18 July 2012 at 14:09

    Thank you for this post! The tip to dry a leaf to see the color is very good, I'm going to do it:)
    Do you know the latin name for the wild plant that doesn't have blue pigment?

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    1. Bryan's Japanese Textiles18 July 2012 at 20:30

      I believe it is: Persicaria tinctoria. There are a few variations around. In the winter the dried leaves are a dusty grey and if you try hard you can imagine blue!

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  3. shiborigirl21 July 2012 at 03:05

    i'm about ready to do a second harvest here in CA. we have had several days of mid 90 degree weather and the dried leaves are dark blue...
    i also used my compost liberally on them. good to know i'm headed in the right direction. these are the pink flowering indigo with seeds from Rowland Ricketts.

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    1. Bryan's Japanese Textiles21 July 2012 at 08:38

      Second harvest already! The two key points are really well composted soil and lots of sunshine. Are you composting the leaves right away or drying and waiting to do them together in winter?

      Bryan

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  4. neighbor5 October 2012 at 08:16

    I love your blog, Bryan -so much good information! although I live in the US, we have a cabin in Shichigahama, near Sendai, and I would love to see your farm and your work when we visit next year, if that is at all possible.
    You are the first I have seen mention the imposter weed. I also took a photo, and, if the plant had not bloomed earlier than my Japanese indigo, I would have never seen it. It got taller, and grew lush with the care of the other plants. I pulled them up and checked very thoroughly to be sure I harvest no weed. I read that the plant will give a yellow dye, but do not know how to use it, and don't want to mix it with my indigo.

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