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Watch celery “magically” change color with this easy celery and food coloring science experiment! A fun, hands-on way for kids to learn how plants absorb water.
When you hand your kids the water hose to water plants, the first thing they probably do is spray the leaves and the above-ground parts of the plants. Did you know that the best way to water plants is actually water at their roots? The question then is, how do plants get water from their roots all the way up to their leaves?
Through a process called capillary action, water is able to climb up the tiny tubes in the plants and travel to different parts of the plant. With this simple and easy science experiment, you can show your kids capillary action at work.
Celery and Food Coloring Experiment
Materials:
- Fresh celery stalks with leaves. The more leaves, the better!
- Clear jar or glass
- Food coloring
- Child-safe knives
Step-by-Step Instructions:
- Fill each glass or jar with water. Don’t go over ¾ way full, leave room for the celery stalk.
- Add a few drops of different colors of food coloring in each glass.
- Cut about 1 inch off the bottom of the celery stalks.
- Place the celery stalks in the colored water. I recommend using the lighter stalks near the center with the most leaves; they will show the most color.
- Wait about 3 hours and check on the celery stalks. Did the colors on the leaves change?
- Leave the celery overnight in the colored water and check on them again the next day. Are the colors on the leaves more visible?
- If desired, leave the celery stalks again in the colored water for another night and observe the results.
Celery and Food Coloring Science Experiment Observations
How did your celery stalks turn out? We were amazed at the results! I did wish we had more leaves on our celery stalks so that the colors would show more, but there were enough to see the capillary action at work.
24 Hours
After we left the celery stalks in the colored water overnight, there was significant color in the leaves. It’s a little difficult to see from afar, so let’s go in for a closer look.
The celery stalk that seemed to have absorbed the most water was the one in the blue water. You can easily see the bright blue colors in the leaves.
The celery stalk in the red water turned yellow, which makes sense as green plus red equals yellow. You can see the red water has been absorbed all the way up to the leaves.
I was worried that the green water in the celery stalk wasn’t going to be perceivable, but I was wrong! You can definitely see the entire celery stalk and the leaves turned a darker green.
The one in the purple water seemed to have difficulty absorbing the water. Even though you can see the purple slightly in the leaves, it wasn’t as apparent as the other three.
48 Hours
We left the celery stalks in the colored waters one more night. You can see that the leaves are more vibrant, but they are also starting to dry out.
The celery stalk in the blue water, in particular, really soaked up the color. You can see that even the stalk changed color.
To see capillary action inside, trim the bottoms of the stalks with a knife. You can see all the tubes that drew up water from the bottom of the stalk to the leaves.
You can go a step further by breaking a piece off the bottom and peeling it back. Now you can clearly see how the color traveled through the stalks.
The red tubes reminded me of the blood vessels in our bodies!
The Science Behind the Celery Experiment
A stalk of celery is made up of lots of small tubes (like straws). They have a fancy name – xylem tubes. These tubes are responsible for moving water up and around the plant. As the celery grows, the tubes transport water from the roots to the leaves.
When the water moves up the tubes, it is called capillary action. Have you ever laid a sponge down on top of a few drops of water? Does the water stay under the sponge? No! It climbs up into the sponge, right? That is because the sponge has lots of little bitty holes (or tubes).
Water droplets like to stick to the walls of the tubes and to each other. It’s like when you are climbing up the side of a cliff with a team. As you go up, you pull the next teammate with you, and he pulls the next one with him, etc. So the result is the water “holds hands” and travels up the tubes together. That is what happens in the tubes in the celery. The water drops work together to travel up into the celery stalk and leaves.
We can see capillary action at work in our bodies too! Our blood vessels move our blood up and around our bodies. The tear ducts in our eyes allow the tears to move up and out of our bodies.
Frequently Asked Questions
How long does it take to see results?
You may start to see color traveling up the celery within 1–2 hours, but the best results usually appear after 12–24 hours. Leaving the celery in the colored water overnight allows the color to travel farther through the stalk.
Does this experiment work with other vegetables?
Yes! This experiment works best with vegetables that have visible stems or veins. Some great options include:
- White flowers (like carnations)
- Lettuce
- Napa cabbage
- Green onions
Vegetables with strong veins absorb colored water more easily, making the color change more noticeable.
What age is this experiment best for?
This experiment works well for a wide range of ages:
- Preschoolers can observe color changes and explore cause and effect.
- Elementary students can learn about how plants absorb water.
- Upper elementary students can connect the experiment to science concepts such as capillary action and plant structures.
Adult supervision is recommended, especially when cutting the celery.
Why doesn’t the color always travel evenly?
The color doesn’t always move evenly because celery stalks have many tiny tubes inside them. Some tubes absorb water faster than others, and small cracks or thicker areas can change how the water moves. This uneven color movement is normal, and it’s a great opportunity to discuss how plants transport water differently throughout their structure.
Final Thoughts on the Celery Food Coloring Experiment
The celery and food coloring science experiment was instrumental in showing my kids how plants absorb water. It clearly demonstrates how capillary action works. And it was so easy to do!
If your kids liked this experiment, you can always try different colors of food coloring and see how well the celery stalks absorb water. As you can see above, blue was the winner in terms of how well the colors showed in the leaves and stalks.
What other things can you put in the colored water and watch capillary action happen right in front of your eyes? We love the rainbow-walking water experiment and the growing-a-rainbow experiment using paper towels! They are a lot quicker than this celery experiment with amazing results, so make sure you check them out.
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