Stimulating the hair follicles helps too. It increases blood flow which increases the rate of growth. If you are trying to grow your hair out before dreads brushing it more often will help. I had heard that laying with you head over the edge of the bed and brushing the hair helps because the extra blood can be absorbed by the stimulated hair follicles. It sounds good but I don't know if its true.

If you already have dreads and you're trying to help your hair grow faster to gain more length the options are similar. Diet changes still work but stimulation is more difficult because you can't comb or brush with dreads. Finger massages feel good and are helpful but it's seems tedious and it never feels like you're getting your whold scalp. The head honcho is a pretty good solution. It allows you to rub the scalp under the dreads without hurting them so you get the stimulation you're after. It also has other benefits like helping dead skin cells exfoliate wich is good....unless you're hanging on to them for some reason. :)