If ever you have attempted to dye grey hair, literally it is next to impossible! So I decided because I wanted a change from my grey to purple, so I stained my hair with Atomic Turquoise hair colour from Manic Panic! It turned out fantastic ! 
I mixed half of the bottle of manic panic with one part conditioner (has to be white) then painted it on to my grey roots just like you would when colouring your roots. BE CAREFUL THIS STUFF STAINS SO OF YOU SPILL WIPE IT UP RIGHT AWAY!
I left it in for the entire day from like 10 am until 2pm while I went about my day then I just rinsed it out, no shampoo.

This first picture is two weeks of washing later, so it will be temporary!