Thanks for the heads up on the spinach! I was going to buy some tomorrow! I won't now.
Bobble-heading previous posters...if you don't do artificial food colours, then these will be a no-no. How bad are artificial food colours? Well, some people know they react badly to them (e.g. my son), and there is research that demonstrates harm to children's development and behaviour which is why the UK are banning several of them. I don't know where you are or what is available to you. So it depends on which ones you would be using, how you react to them, and how comfortable you feel with artificial additives in general.
Have fun, whichever type of colour you go with!