Learn more physics!
How will food coloring affect the growth of plants when added to their water (one or two drops), especially on cherry belle radish?
Mountain pointe, Phoenix, AZ, USA
Great Question! I actually did this for my fourth grade Science Fair
project. I used beans instead of radishes, but I think the answer
should be pretty close.
Unfortunately the answer is that it really doesn't do much. Food
coloring is non-toxic, so it doesn't poison the plants. If you use
enough of it, you may get a little tinting of the leaves of the plant
after a while, but the plant still grows pretty much the same.
p.s. Food colorings are often added to water for plants to alter
the appearance of the plants. I bought some nice blue flowers once, and
found that huge amounts of blue food coloring leached back into the
water in my flower vase after about a day or so. It probably doesn't
help the plant grow to have the extra food colorings present, but it
does not hurt either. We expect the radishes not to behave any
differently from other plants in this respect.
(republished on 07/18/06)
Follow-up on this answer.