This one's pretty easy.
Buh-bye, Color Resistant Gray Hair. You've been evicted.
My hair before (3 weeks after professionally applied, 100% gray coverage)
The plan (since my hair isn't going to magically start accepting color anytime soon) is to gradually lighten my hair (via color and highlights) until I am a medium brown (level 6 for you pros out there). I am currently dark brown (level 3) and while going so light makes me nervous, I have a better chance of hiding the gray with light hair and therefore can hopefully get away with color appointments spread 5-6 weeks apart. Otherwise, according to the very fabulous Toni, I'll have to color my hair every 2-3 weeks. Um, in that case, lighter it is!