My hair has always been long since I can remember.
As a toddler my hair was down to my waist.
@.@
So, I've never had a problem with growing out my hair, it grows like a weed^^"
I have to cut it every two weeks.

But I suggest eating alot of fish to grow out your hair. For some reason fish oil grows out your hair, and I think nails as well.
So, eat alot of protein^^