Here is the indigo vat recipe that I have been working with written by Earth Hues. They are a wonderful company supporting agriculture, natural color and artisans around the world. I order my pigment from them and every time I order, I ask where the pigment is from. Most of the time the pigment has been from El Salvador. This is the recipe they provide and it's fantastic!
Fabric dye - Non-fading Pokeberry Recipe - Pokeberry colors range from bright fushia to magenta to raspberry, and will last for several years by following this recipe. Over-dyeing fabric in indigo, once the pokeberry is set, will give purples. The berries are gorgeous, but fatally toxic. WEAR GLOVES!