Here's what happened...
I first coloured my hair with the Garnier Nutrisse Cream in 913 at the end of July. The outcome, I thought was quite decent, nothing amazing, but for $10 and my first time attempting this at home, I was satisfied with the results. However, as the days went by, I realized how yellow and brassy the colour looked. I did only do my roots, but it was still noticeable. I religiously use my L'Oréal Paris Professional Shine Blonde Ceraflash Shampoo for blonde hair. It's the absolute best purple shampoo and usually eliminates all signs of yellow in my blonde hair. Unfortunately, it didn't do much for this situation.
About a month or so later, I decided to try again, I went one shade lighter, thinking it would be less yellow. However, the results were the same, just a slightly lighter shade of yellow. My hair is naturally a dirty blonde shade, so it's not as if I'm attempting to dye my dark brown roots a light blonde shade. I used the Garnier Nutrisse Cream in 101 the second time.
I followed the instructions precisely both times, and used the follow up conditioner for several washes after both treatment, but nothing has made the colour less yellow. It's not Big Bird yellow, don't get me wrong, but for someone who is used to ashy/sandy blonde shades, this box dye is not cutting it.
I would therefore not recommend using the specific box dyes to achieve a neutral or ashy blonde at home.
If anyone has tips or product recommendations that could save me $100 at the salon next month I would be very grateful !