I seriously know what helps hair grow since my hair NEVER used to grow.
First, I thought because I wanted my hair long I shouldn't cut it, that was fault #1...
Trim every 1-3 months no matter what. Even if its just a centimetre. It helps the hair go a long way.
#2 was my hair lacked moisture. I started to use this cream that one of my friends gave me that her room-mate makes. The stuff is really good. (I am selling several ones that my friend gave me that I don't need. You'll find that in a different forum.)
After this cream, I noticed my hair was stronger and didn't fall or broken with ease as it used to. Because dry or damaged hair is really fragile so that affects its growth.
And last but not least #3, genetics and medical health. If your mother had uncontrollable long hair and a head full of it, there is a chance that you'll inherit her strands, and if you find the opposite of your mothers head, then the opposite of the former can be true.
Keep your health in check. There is no specific vitamin or food you can eat that will help your hair grow dramatically faster, but if you have an overall good health and stable condition, that can help your hair grow at its fastest.
I hope my tips help.
But I will remind whoever is trying to grow out their locks that you should never put the scissors away because you want to grow it out. Instead trim your hair. Because hair with split ends or damage will not grow.
Miss Lovely