At 50 my red hair is starting to grey. I’ve been using a L’Oréal permanent colour on it for w few years but my hair grows really fast so I have roots within three weeks. It also seems to wash out of the grey strands really quickly. I can’t use henna as my hair already has colour on it so I’m wondering the best way to get a coppery red that covers the greys for longer. I don’t want to let it go grey, I’ve always been a redhead.