Select the shorter sticks of celery that has lots of leaves for the best results. Chop around a cm off the bottom (the bit that is white) and place them in a glass with water and food dye. I have found that blue and red seem to work the best. Over the next 24 hours we observed the colour of the leaves.
One hour later and we can already see a tinge of blue on the tips of the leaves.
After only 2 hours we can already see a lot of blue spreading all over the leaves.
The higher leaves appear to be a darker green as the blue starts to cover a large are of the leaves.
Twenty four hours have past and we have a lovely bunch of blue celery. The tip of the plant is looking really bright. We are now ready to take a look inside. We Chopped the celery into half and had a look. It resembled the inside of a stick of rock. I explained to the children that the roots take the water from the ground and the stem acts like a straw drawing up the water and taking it to the leaves and the rest of the plant.
We then sliced the celery length ways.
Try this experiment with different colour food dyes and make yourself a bunch of rainbow celery.