I promise you do NOT want to do that (food coloring) to cannabis. If the roots were even able to uptake the dye as blue dye, and transfer it into the buds, would you REALLY want to be smoking dye? Might be FDA approved for EATING, but I'm all set on smoking it, thx. A friend did a Miracle Gro hydro grow as a joke and noticed that the plants DID take on a slight blue tinge from the dye, but tasted about liek you'd expect them to- chemically. Blech.

Birth control pills- people think that estrogen makes the plants be female. lol.

At least watering with Kool Aid you WOULD be adding sugar, which plants LOVE. So of all the things on the list, IMHO it's the safest. lol.