Japanese Indigo

Japanese Indigo, or Persicaria tinctoria, is also called Dyer’s Knotweed.  It is a smart weed, in that it roots from nodes along the stem, and grows vigorously.  It is not ‘true Indigo’ as Indigofera tinctoria which is grown in warm, long season climates, and contains a lot more indigotin dye than Japanese indigo does.  But, Japanese indigo is so vigorous, easy to grow and easy to seed, that it is easiest to grow in all cooler climates and is grown in Japan.

You will notice that the seeds that I sell have some dried flower petals on them.  It takes a good bit of friction to remove it and I haven’t come up with way to do it that I don’t fear causes too much abrasion to the seed and doesn’t hurt my hands! I read another seed seller saying how difficult it was to remove the dried flower petal from the seed, and I felt very vindicated with how difficult I found it to be when you have such a large quantity!

The seeds you have received are the round leafed variety of Japanese Indigo.  There is a narrow leafed variety, but it seems more susceptible to getting sun burned, and it takes longer to regrow and flower to produce seed after a harvest in mid summer.  Due to this, I have read of some indigo farms in the western US, say that they would be focusing on growing the round-leafed variety, because they risked a frost coming before the narrow, long-leafed variety got around to blooming and producing seed. 

Japanese Indigo should be planted in a sunny location after danger of frost.  The plants can get sun burned when it is very hot and sunny out.  It likes lots of water!  And make sure to give it some water and some fertilizer after you harvest it.

It contains the most indigotin before it flowers, so it is best to harvest and use before it flowers, but still contains enough during flowering to have fun with.  The easiest, quickest way to dye with this plant is to harvest the stems, and strip the leaves off the stems. Use the leaves as soon as possible. Stick the stems in water, and they will readily root and can be planted again, though, they practically grow in water! 

Take the leaves, and a bit of salt and some yarn, and squish it up!  Liquid will begin releasing out of the leaves and begin to dye the yarn!  Work at it a while, so that the whole yarn is evenly colored, and if you didn’t wear gloves, your hands will colored too!

There are more complicated ways online that you can look up, that use ice water, and salt and blending, but that seemed like more hassle than it was worth, when you can get the same effect with just salt and the leaves. 

You can also harvest the stems and ferment them and harvest the color to use as a paste or dry to use as a powder, or you can do a chemical reduction and dye with it directly.

There is a wonderful facebook group ‘Indigo Extraction Methods’ that offers a lot of help, and that you can search and find videos and pictures of what each stage should look like, and also helpful, was the description of the sweet smell that the fermented indigo vat gives when it is ready.

Fibershed.com offers some of the best information about indigo extraction online.  I have purchased a few expensive books on Indigo, one of which is referred to as the Indigo ‘bible’, but really, you can get really wonderful free information from the above two sources. 

This is such a fun, hardy dye plant, and if you collect the seed, you will always have plenty! The ripe seeds should be shiny black and hidden in the dried little pink flowers as they turn brown. It will self-seed as well if the area where it was planted is left undisturbed.  I have found the self-seeded seedlings that come up the next spring to be exceedingly hardy to frost and cold weather.

You may notice a pervasive weed in your yard that looks much like Japanese Indigo.  It has the same flower, and stem node growth habit, but a longer, narrow leaf with a dark smudge spot in the middle of the stem.  This weed is related to Japanese indigo but contains no indigotin.  It is called ‘Oriental Lady’s thumb print.’  It is a smart weed.  I had a ridiculous abundance of it growing everywhere last year! 

If you are ever unhappy with seed or any other product you receive from me, please let me know.  Especially with seed, I feel that if the seed should not produce well, the waste of the growing season is the biggest shame and a refund unfortunately cannot make up for that loss of time.  You may find some unripe seeds, but I include extra seeds to make up for that.