How to correct hot roots at home?

BEFORE I EXPLAIN: Please don't give me any grief about coloring my own hair or for not going to a salon. I don't have the $200+ that it would've cost me to do that and this all started as a way to help out a fellow friend who is in cosmetology school.

So, I went from dirty blonde-ish/light brown hair to auburn. I had my hair stripped of color about 2 months ago and have just dealt with the boring color left afterwards. When a girlfriend said that she might be able to help I figured, if it didn't work out I'd just go all over black. But the color turned out great except for a little less than 1/2 an inch where my new growth pulled a lot more red than the rest of my hair. Is there anyway I could just use highlights/lowlights to conceal it? Or anything else I could do?