Lerping between two colors to create day/night effect in unity2D

hey all!

I'm trying to make a day night cycle, well not trying I've almost finished but I need to create a sunset effect , so my first guess was to lerp between three colors, blue for morning and then orange for sunrise and then orange to a dark greyish color but unfortunately it wouldn't work, I did this by trying to change the background color on the camera since my game camera is front facing a bit like terraria's (I'm not making a terraria clone :D ) , the color of the background went from blue to dark grey straight away, I'm not really sure if this is the best approach to deal with a day/night cycle, but hopefully you guys can help me out a bit, thanks !