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.