How to naturally darken light brown hair?

How can you darken hair hair naturally?

• How can you darken hair naturally, using products that don't involve any dyes or chemicals? I've done a lot of research, and people say things like coffee (though I don't want to end up smelling like coffee the whole day), rosemary, sage, thyme, birch or black tea can darken the colour, or henna/ indigo and some other random things that involve vinegar and such. I am asking anyone who has had experience with this sort of thing which one of these would be best for results. I had black hair before,but it got bleached by chlorine and is now a light brown. Please, do not reply with "I dunno" or "Like what ya got! Lots of people would die for natural brown!" or "You can't." Please don't post anything unless you are actually addressing my question, thankyou.

• Answer:

  use hair henna its natural u can find in a indian store