Using the fresh leaves of indigo (Polygonum tinctorium) for dyeing is an alternate way of using indigo. There are many recipes on the internet for dyeing with fresh leaves that give wonderful clear hues of blue, on silk, cotton and wool.
Time: About 4 hours
1. Pick 16 oz. of fresh indigo leaves, put them in a bucket and add just enough hot tap water to cover the leaves.
2. Heat the solution to 160 degrees F. over a period of two hours. Don’t heat it too quickly.
3. Strain the liquid and squeeze liquid from the indigo leaves into the strained liquid.
4. Add 2 Tbsp. baking soda to the liquid and stir a little.
5. Pour the liquid from one bucket to another for a few minutes, or until the solution turns dark green/blue. This oxidizes the dissolved indoxyl, changing it to indigo.
6. Dissolve 2 Tbsp. Thiox in warm water, pour it into the dyebath, cover and set the pot in a larger container of water that is just hot enough to keep the dyebath at 100 to 120 degrees F. for about an hour.
7. Meanwhile, soak 2 to 4 oz. of yarn in hot water.
8. When the dyebath has turned yellow, add the wet yarn—carefully, to minimize adding oxygen to the solution. Leave it in the dye for 20 minutes. Remove it gently and let it oxidize by hanging it on a wooden rack. The yarn will turn blue as it reacts with oxygen in the air.
9. Let the yarn dry for as long as it soaked in the bath. One dipping and airing is usually enough to richly color wool yarn, but for intense colors on cotton or silk, repeat the soaking and airing two or more times. You can put successive batches of yarn into the same dyebath, getting lighter colors each time, until the yarn no longer turns blue. Then discard the dyebath. It is safe to pour down the drain. Scrub stains from the pot.
10. After the final airing, wash and rinse the yarn.