You might have seen photos online of a popular experiment for children to learn about how water travels through plants. You are supposed to put food colouring in water, put some white flowers in and wait to see the petals changing their colour.
Seemed very easy and streigh forward so went to Tesco and bought their food colours, cut some flowers from our garden. I added colours in all but one of the cilinders and my flowers died in less than 12h. The flower left alive was the one in regular water and lasted well for about a week.
So I guess my little one has lernt a biology lesson afterall, but not the one I was hoping. Stay away from food colouring folks. It is not that safe and edible as we may think.