How long does it take for flower to change colors in colored water?

I've tried to do this science project, and according to one paper it should start changing within hours. It has been 2 days and the flowers only have a few dots of color to them. How long should it take? I've used mums and carnations. Is there another type of flower that works better?

How long does it take for flower to change colors in colored water?
I don't really know how long but I don't think it should take 2 days. Carnations normally work pretty well. I bought some daisy's the other day that were dyed so you could try that. One thing to keep in mind is you want to cut the stem right before you start - it simulates the "veins" of the flower and draws the color in better.