Let's review the experiment first. The reason
the celery sticks get colored is because the
celery absorbs the water through its capillaries.
This is what plants do in order to get water,
which is one of the essential ingredients for
growth. The capillaries are located in the xylem
of the plant, which is the water transporting
tissue in a plant. The capillaries sucked the
water so high that even the leaves should have
changed color from the colored water. The celery
should have sucked all colors of water similarly.
If you used red and blue, the blue just may not be
as visible in the green celery as the red is. If
you peel back a layer of celery for both colors,
you should see the veins of the celery dyed that