Natural hair regrowth requires that hair pass through 3 different phases: the anagen phase, the catagen phase, and the telogen phase. Read how to regrow natural hair in the article. The anagen phase, perhaps the most important of all of the hair regrowth 3 stages, is the initial stage that kick starts your hair growth cycle. Your hair will be in the anagen phase for up to 90% of its entire hair cycle, and the cycle can last any where from 3 to 7 years in duration. You should expect your hair to grow about ½ inch a month, or 1 centimeter, and it will continue to grow and grow.