How long does thc stay in hair follicles?

Different answers: I have read that one time use might not even show up. Most answers say that if use is regular, then it will stay for about 2-3 months. One person said that his parents, both of whom are police, told him that it could stay for a year. Hair grows at 0.5 inches per month, so they usually cut off three months of hair growth (1.5 inches) for the sample for detection. Why not just not use the stuff?

Hair has no blood: So, once THC is in the follicles there's no way for it to get out. It stays in the hair until it is cut and grows out.