Now that some of the flowers on my indigo plants (Polygonum tinctorium) have become faded and dry, I am beginning the process of saving seed for next year’s crop. First I start by cutting off the dry brown flower clusters and storing them in a paper bag for a few days to dry further. Because we have had some early rains which make the seeds moist, (and because the birds seem to love eating my indigo seeds), I have also cut some of the stems where the flowers are not yet completely dry, and am hanging them to dry inside a paper bag.
Next I pick the dried flowers off the stems and place them in a large metal kitchen strainer. You can also use an old window screen, as long as the screen is fine enough to keep the seed from falling through.
Then I just rub the dry flowers against the strainer so that the husk around the seeds is gradually removed and the little black seeds are released. Some of the chaff falls through the screen, so I add that, plus the old stems, to my compost pile.
Then I put the contents of the strainer on a large plate and blow softly to remove more of the chaff, but keep the seeds. This is a bit tricky to do, as the seeds often blow away too, so I end up separating the seeds from the remaining chaff by hand.
I noticed that some of the seeds are still green, so these I will not keep, as I want to make sure I am only using the viable mature seed. I will try storing my seeds in a cool, dry place, in both a jar and an envelope, to see if one storage method works better than the other. Seeds from Polygonum tinctorium are good only if they are used for the next growing season, and cannot be stored longer.
Here’s the resource page of Richmond Grows Seed Saving Library if you want to learn more about saving seeds in general. And here is a beautiful and information-filled booklet about seed saving from the School Garden Program at Occidental Arts and Ecology Center.
When I have finished processing all my indigo seed, I would be happy to share it. Leave a comment if you want me to send you some seeds and then we can talk via email about where to send them.
I look forward to another crop next summer, with further experiments in indigo dyeing with some of the other methods I have recently learned.