Colours?

Last weekend I bought an orange coloured cauliflower. In the past I have bought all the different designer colours purple, green and goes-with-everything-white. I have been noticing all week while cutting it up that it has these rings of orange colour down the stems and I have been wondering what in the heck "they" colour it with. Does anybody know? Do they water it with food colouring while it's growing? Do they inject it with food colouring shortly before sending it to market? What other colours have they tried to produce, but failed? Did red turn into a grotesque pink? Did they ever try to make a gothic (black) one? I am curious and a little perturbed. But I might stick with the classic white from now on.