The best way to colour your beard naturally is with hennas. Hennas are completely all-natural, do not contain any chemicals, and last for months (if not years). Henna colour fades over time, so if you'd like to refresh it with a new coat of henna, go back and add more. You can also use beets to dye your beard naturally. You will need to crush them in a blender and apply them to your facial hair. This will stain your skin, so be careful and use latex gloves for the best results.