Indigo is a natural dye that is obtained from the plant Indigofera tinctoria. Itâs rich, dark blue in color and is mainly used for dyeing clothes, especially denim. In fact, it is known to be one of the oldest dyes to be used for textile dyeing and printing. However, it is now also being used in combination with henna as a natural hair dye. Interestingly, indigo offers some great benefits for your hair when used appropriately. Advantages Of Using Indigo?