ANSWER - There's little out there in terms of specifics. The magic usually associated with hair growth is the perception that you should only ever cut your hair on the full moon as this promotes health and encourages it to grow faster. Opinions on this are divided but it may well be worth a try.
Hair grows to a predetermined length - this is a science thing but I can also vouch from personal experience that hair doesn't grow at a set speed. My friend and I both started growing our hair at the same time and hers is nearly at the base of her back now whereas mine wouldn't protect my modesty if I had no top on. So I do sympathise...
Heat helps promote hair growth as does keeping the hair in good condition. On a practical level you could try warming a small amount of argon oil, applying to the head and then sleeping in a swimming cap to seal the heat in. You'd certainly have beautifully conditioned hair even if it didn't have much effect on the growth!
There's nothing to say you can't work a spell to speed up the process. If I was doing it I would cut a lock of my hair and then carefully tie the individual strands together to form a single long thread. I would anoint the hair with an oil associated with abundance and/or prosperity (basil, verbena, almond) and clip it into my own hair for a short period each day while visualising the growth of the rest of my hair speeding up to match the length indicated by my spell.