Capillary action of plants is revealed by food coloring experiment by placing flowers and celery in water with food coloring. We had some success and a failure. Plants use capillary action to bring water up the roots and stems to the rest of the plant. Be sure to scroll down for free student observation PDF to download. 

Food Coloring Reveals Capillary Action of Plants

First, we tried baby’s breath and some antique Carnation flowers that had been in an arrangement (so they were not quite fresh). Basically, it didn’t work. I asked the kind florist at Maple Grove Whole Foods who explained I waited too long. We enjoyed our flowers first and then tried to see if the capillary action of plants could be demonstrated. She said just like a Christmas tree stops drinking water, the flowers did, too. That is a good analogy for children. We added food coloring to the older flowers in the first attempt.  Too late!

capillary-action-flowers-food-coloring attempt one

If At First You Don’t Succeed

We had no luck with these even after several days. I thought it should have only taken several hours. We started over!

Fresh Carnations from the Florist

Next, we actually went to the florist and bought real and fresh carnations. Sarah is the Outstanding Employee from Whole Foods who was kind enough to help me and figured out “old fashioned” carnations would have worked better. I had noticed many people used carnations for this experiment so there must be a reason why. For good measure, we also bought celery for the same reason, I have noticed online many people use celery to demonstrate capillary action in plants. Here they are ready to absorb the food coloring! carnations-and-celery-in-water-with-food-coloring

After a few hours, we had action and could observe some changes. Blue worked the best, and purple worked OK. That orange looked like it might not work, and it never did work on the flower even though I added more food coloring. Orange did work well for the celery. You can see some blue around the tips of the celery leaves, also.


By the next day, more color was showing except for the white flower in the orange food coloring. It was easiest to observe by removing the plants from the test tubes and colored water.


We tried to see what had happened with close observation.


Download Your Observation Pages

The free student observation pages to download are here. Below are the pictures of the two pages included. First is the celery page picture.


This is what the carnation page looks like. Just print the page or pages wanted.


Once we had the magnifying glasses out, of course, there were more things around the house to observe. What was inside the Paper Lantern plants?


And how about the pine cones we painted last year? They needed a close up look, too.


We hope you have fun learning if you try this experiment! Just remember to get fresh flowers and or celery. Carolyn


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