Do I have to cut my hair if I want go with a lighter hair color?

I have pretty long hair and I want it to get longer! I have died my hair black a few times but it has been a while since I did so there's a good two inches of roots that is my natural hair color (dark brown) except the bottom of my hair is still jet black, I want to go lighter like A LOT lighter but I do NOT want to cut my hair (I know people say it grows faster when you cut it but I doubt it) I'm pretty scared to go to a salon because I am never happy with the results when I do. HELP