How long does marijuana stay in your hair folicules?
A very long time can be years
No, exposure to the smoke of marijuana does not stay in the hair forever, but duration does depend on the frequency and severity of exposure and frequency of washing hair. What does happen though is, if a person smokes marijuana there are traces of it that reaches the follicles and grows into the hair. A hair sample can be taken from the person and tested and can prove that he/she smoked marijuana.
Permanently. Whatever you do, will show up in a hair test until the hair that was growing is gone. It will not, naturally, wash out of your hair as your hair is partially formed of the toxins in your blood. I refer you to this link, which is about marijuana, but the idea is the same: http://www.howtocleanyourbody.com/long-does-marijuana-stay-your-system-hair-testing-a-3.html