I'm a really big fan of indigo. Blue has always been a favorite color and I have always felt more at home in blue jeans than any other item of clothing. It all sort of fits. But when I started to dye things with indigo I really fell in love.
Setting up the indigo vat and keeping it producing wonderful blue color can be tricky. It requires a complex process to balance the complex chemistry. It's very different than dumping your yarn in a dye pot and adding a chemical dye to get whatever color you're after. I love the chemical dyes and we use them often. But nothing is so wonderful as working hard to get the indigo vat just right, then carefully plunging your yarn into the vat. When you pull it out it's a slightly sickly looking pale green which turns to a rich dark blue as it oxidizes. It's magic.
Indigo is the universal donor of dyes. It doesn't matter what you throw in the vat, it will come out a rich deep blue. Indigo is the natural dye that doesn't care if you are dyeing wool or cotton, linen or silk. That's because it doesn't chemically bond to the fibers. It's molecules are large and get trapped within the fibers. It's why blue jeans fade out and why you often need so many dips into the vat to get dark deep color.
I bring all this up because I got a call last week from Sandi Elsik, the lead gardener for the dye garden at the Houston Center for Contemporary Craft. The Craft Center garden is a wonderland of natural dye plants. They grow several different varieties of cotton along with madder, indigo, coreopsis and other dye plants. Sandi worked hard to get the indigo plants thinned out and had some wonderful plants to give away. Did I want to make the trip down there to pick them up? Hell, yes.
One of the wonders of indigo is that the precursor, indican, is found in several very different plants. Historically, woad (Isatis tinctoria) was the source of indigo across northern Europe. I tried to grow it once but was not successful. Woad has a two year life cycle and timing is very important. Somehow I missed the window to harvest the leaves and wasn't willing to wait another two years. Polygonum tinctorium, also known as dyer's knotweed, Chinese indigo and Japanese indigo, originated in southeast Asia. This subtropical plant produces about twice as much indigo per weight of leaves as woad does.
Indigofera tinctoria, also called Java indigo or "real" indigo, has become the dominant species of plant used to create indigo dye. This is not because it's indican is any better than that produced by any of the other plants. Nor does it produce more than Polygonum tinctorium. It's because this plant can be grown in a much wider area, including India, sub saharan Africa, the far eastern islands of Java, Sumatra and Indonesia as well as northern and western South America and Mexico up through the central US.
Last Thursday, my husband and I drove down to the Craft Center to meet Sandi and pick up the indigo plants. These are listed as Assam Indigo in the genus Acanthaceae. None of my books on indigo list this genus and Google hasn't been much help. According to Sandi, these plants are tender perennials and will bloom in the winter, January probably, if they don't freeze before then. I'm supposed to harvest the leaves and stems before the first frost by cutting the plant savagely back to almost the ground. The leaves and stems will both provide indican and I will be on my way to dyeing. I can't wait!