it depends on how much yield you are looking for you can do a grow entirely with one or the other but you will get better results with mixing them the blue spectrum promotes veg growth because it simulates summer sun and the red spectrum promotes budding because it simulates fall sun and tells you plants that summer time is over and it's time to flower you will be fine vegging them with the light you have but when you got to 12/12 you will want to get some more red spectrum