Thinking of colouring the rest of my hair blue black

[glittergloss]

I've been hair dye free for maybe 6 months now but I've been hennaing my hair every month or two. My hair was bleached multiple times before so whenever I henna my hair, the bleached part turns very red and vibrant but my roots only get a reddish tint colour. My natural hair colour is soft black. Anyways, my henna on the bleached part fades every few wks to a dull looking red and I can't stand the look of it. I've been thinking of colouring the coloured part of my hair blue black but I'm not sure if it'll blend well with my roots (soft black). Or should I just colour the rest of my hair soft black? I just love the look of a darker black shade if I have to colour my hair again. I really don't want to colour my hair using chemical dyes anymore but I think I just can't stand the look of my hair right now. This will be the last time I'll be colouring my hair using chemical dyes so don't want to make a mistake. Will the permanent black hair dye fades over time just like henna?
Thanks

[cat11]

I was in a similar situation before when I had dyed and bleached hair and I wanted to start growing it out natural. I wanted to dye it one last time to the closest thing that would blend in with my roots so i got a brown color that ended up being darker than my roots but Im slowly growing and trimming it out.

I would go with the soft black if thats closest to your natural color so the "line" isnt as obvious later. You wil probably have some red from the henna shine through no matter what.