Indigo is a natural dye that is obtained from the plant Indigofera tinctoria. It's 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?

• It is an all-natural hair dye that does not harm your hair in any way.
• When mixed with henna, it gives your hair a rich brown color.
• When applied over henna treated hair, it gives a lush black color.
• Regular use of indigo on hair can treat and prevent premature greying.
• Indigo hair oil stimulates new hair growth and prevents scalp infections.
• Indigo hair oil also treats dandruff and conditions your hair.