I have a friend with dreads who dyes them pretty often. You have to use a lot of dye. Massage the dye into the dreads so you know it's getting all the way through and leave it set for longer than the advised time (if you're using safer, non-bleach based dyes, of course) and rinse as well as you can. It will last for a while if you maintain it properly. But it may also stain your bedding, so protect your clothes/sleeping area if that's a problem.
Great advice! Thanks!
For dreads you need more dye. A lot of it will get soaked up into the dread and not just dye the surface.
So just slather on lots of dye?