This colored celery experiment has been on my pinterest list for a long time. I finally decided to buy some celery, and we had some free time last weekend to try a 24 hr experiment. I also consulted this celery experiment for toddlers post our experiment to see their results.
Basic take home message:
Plants need water and use it during photosynthesis (plants need water and light to grow). We can see how the plants take in the water if we use colored water. It also turns the celery different, cool colors!
The experimental set-up:
We decided on 3 colors for the celery experiment: yellow, red, and blue. We filled the cups 3/4 full and used 4-5 drops per color.
J was a great helper.
We also at the last minute decided to add a control, which is something we can use to compare the other celery sticks to when the experiment is over. This celery stick had just water with no food coloring. We only had a small celery stick left at this point.
Big J and I asked J to guess what was going to happen. He had no idea why we colored the water, and his hypothesis had nothing to do with the colors. He did guess that the water was going to go down.
I thought that was a great hypothesis, and I wanted to make sure that J was able to see if he was right. You can barely see it in the beginning, but we used a dry erase marker on the cups to mark just above the water line (it's green on the yellow cup). The dry erase markers washed off in the end, in case you are worried.
The experiment I pinned on pinterest ended up waiting 24 hrs, but we weren't seeing great results. We documented results at 24 hrs and 48 hrs.
Results, aka what happened:
At 24 hours we were able to see blue spots on the celery in blue water.
Our celery in red had a scratch on it. The scratch turned red and you could see the water leaking out, but there were no colors on the leaves at 24 hrs.
After 2 days (48 hrs), we extracted (took out) all of the celery sticks from the water. Here they are from left to right, no color, yellow, blue, red:
The control (no color) ended up looking healthier after 2 days. It was the smallest and weakest looking celery stick at the beginning. Yellow didn't really have anything to report on. You could see a little yellow in the celery veins leading up to the leaves, but there were no spots on the leaves.
Blue was our favorite. Here's a close-up of a leaf with blue spots and a blue vein behind it, so neat:
Red also gave us some interesting results. Here's a close-up of minor red spots:
And I (carefully) dissected the celery stick to get a better picture of the innards of the celery:
As for J's hypothesis:
All of the colors of water went down. J hypothesis was correct! We didn't compare which one went down more than others, maybe next time. Looking at the pictures from the experiment, there was no super visible difference between the three colors.
Note, that I took the celery out. The height of the water was slightly higher with the celery stick in it, but it was definitely visibly lower than the initial height of the water.
Potential problems with our experiment:
We didn't put the celery sticks in direct light (no space for it in our small apartment). Maybe if we repeat this experiment, I can clear out a space next to the windows.
For older kids:
Definitely don't forget the control. Preferably, your control will look like your other celery before you start. It would make for better comparisons when the experiment is over.
Dissect (cut apart) your results and document everything you see.
Repeat the experiment in different places. Try a dark closet, a window sill, and normal room lighting.
Try different plants. This site says carnations also work.