I grew out my hair for 5 year's, no special treatment's. In the summer I was out all the time, because the sun make's you're hair grow faster, depending on how much you're out in the sun.
You can have special hair treatment's, to grow out you're hair or these tip's I found on the internet. Maybe it might catch you're attention.
http://hair.allwomenstalk.com/natural-remedies-to-make-your-hair-grow-faster