Home dye job disaster - lighter roots

[GuiltIsMyMiddleName]

In an effort to start 2015 in a frugal way, I decided to colour my own hair.
As the title suggests, it didn't go well.
I last got it done at the hairdressers a couple of months ago and it was a warm light-ish brown colour (permanent).
Went to Sallys hair supplies and bought some Majirel in a slightly lighter dark blonde colour (perm).

Put in on last night (mixed with my 20 vol 6% developer) and now I've got darker ends and lighter roots where the virgin hair was.
Im guessing it's because i went slightly lighter? If i went the same colour/darker, would it have worked?
Should I attempt to correct this myself (I'm assuming I'd need to strip the dark colour out?) or just admit defeat and go to a professional and get it sorted out?
Thanks in advance for any advice.

Yep, you've got "root glow". Basically you can't lighten hair with permanent dye unless its virgin hair, so the dye has added a little more colour to your already lightish brown, but the 20 volume developer has lifted your virgin hair a bit and only deposited colour to the base level of the new colour (was it a base 6 or 7?) so you have two tone hair.

There are 3 solutions. One would be to "match" your roots to the rest by doing a root only dye in a darker colour to match your ends.

If you want to go lighter the other two options are to either strip the existing colour out and then try and get a colour match (this is faffy and tricky, but can be done, and involves waiting a week inbetween stripping the colour out and re-dying otherwise the original colour can reoxidise and you are back to square one) or bleaching it out/or lightening the overall hair colour with something like highlights and then maintaining your new lighter colour by just dying the roots.

Bummer!

Tatty, thanks for taking the time to reply and explain all that.
I think from your reply, what I might do is try and match the roots to the rest of the hair (the colour I used was 7.03) so I might just get a 'brown' base and do the roots only with that? I'm guessing a 5 or a 6? Do I need to mix the same amount of developer (75ml) or should I use less?

Sorry, just saw this.

5 or 6 will be fine depending how dark you think the rest of your hair is. You probably won't need a whole tube of Majirel for your roots, I suggest using half (use a tablespoon measure from your cooking drawer as that is 25ml which is half a Majirel tube) then measure a tablespoon and a half of developer and mix it in. This will be plenty to do roots only.

If you are desperate to go lighter you could then have a half head of higlights (fine ones not chunky ones) and next time you have roots, go up a couple of shades and it should hopefully blend quite well. This is how I went light from a 5 base, I had a whole head of highlights that lifted it beautifully, then when I got the dreaded roots just started doing my roots with a level 8 and it looked an exact colour match to the body of hair.

Thanks Tatty! Really appreciate the advice x