If your hair color is brown then you can also use it by mixing indigo powder in henna. To apply indigo powder with mehndi, put half of the indigo powder in the amount of mehndi you take. Make a paste by mixing henna and indigo powder with luke warm water. Keep this powder for at least 15-20 minutes, after that apply it well in the hair. Wash the hair with clean water by applying it on the hair for one hour.
Indigo powder is a sure shot natural remedy for premature graying of hair and imparting natural black color to the hair. Using chemical-based dyes can speed up graying of hair and result in loss of hair colour.
Yes, it is completely safe to use henna and indigo powder on hair if you have ensured that the products are 100% natural, organic and free from any chemicals.