Color-Changing Flower Experiment

Ah, Spring. There’s something so special about watching the vegetation come back to life as the days get longer and warmer again. My older kiddo has made it a habit of searching for new flowers on each hike and neighborhood walk we take. He likes to use the Seek app on my phone to identify what type of flowers they are and then jot them down or draw them in his nature journal.

After one such walk and journaling session, we stopped by the local grocery store, and he spent some time admiring the brightly colored carnations on display. He asked me how they found such bright flowers, and I told him they used dye to make them that way. He looked a little baffled and asked, “you mean like with food dye?”. I nodded, which then prompted him to ask, “Can we do that with food dye?”.

I told him it was certainly worth a shot, so we purchased some white carnations and planned out our experiment. I absolutely love these moments in our homeschool. When I can say yes to his curiosity and head down a fun rabbit trail that will lead to both fun and the learning of concepts he can apply right away. Thankfully, this particular rabbit trail involved a pretty easy experiment that required very little prep and supplies. How could I say no to that?

Supplies

There’s a good chance you have most of these things already at your fingertips (other than the flowers). All you need is:

• White Carnations (other flowers work as well, such as daisies, but carnations are usually faster)

• Clear cups with water

• Food dye

• Color-Changing Flowers Experiment Worksheet (or science journal if you keep one!). I created this free printable option for you to download.

• Pen/pencil and colored pencils or crayons to record your experiment and colors.

Let’s Experiment!

With supplies in hand, let’s get started!

1. Make your hypothesis! What do you think will happen to the flowers?

2. Choose which colors you want to try. My kids love rainbows, so we did red, orange, yellow, green, blue, and purple.

3. Cut the flower stems at a 45-degree angle to fit the cups. This angle increases the surface area, which allows more water to travel up the stem. TIP: Avoid using dull tools to cut the stems since this can hinder their ability to uptake water.

4. Add water to the glasses (about ½ a cup should do the trick depending on cup size).

5. Add about 30 drops of food coloring (or more) to the cups and stir.

   • For orange, add 15 drops of red and 15 drops of yellow.

   • For purple, add around 20 drops of red and 10 drops of blue.

6. Add at least one flower to each cup.

7. Check the flowers every couple of hours to observe any changes.

8. After at least 6-8 hours, record your observations (we waited about 24 hours to record the results).

   • What happened to the flowers?

   • Did any colors work better than others?

Try This: If you want to take your experiment further, try carefully slicing a stem in half to place one half in one color and the other half in another color.

Time Zero (Start)

24 Hours Later (Finish)

Our Results:

The first time we did this experiment years ago, our flowers just barely changed color at the tips of their petals. The colors that worked the best were the darker hues (especially blue), while the yellow barely showed up at all. We hypothesized that we didn’t use enough food dye in our original solution.

Fast-forward a few years, we tried this experiment again as part of our spring equinox celebration. After making some tweaks from our original experiment, we had much better results this year! We saw the colors leaching into the petals within an hour or so and saw quite a difference after 6 hours.

All of our solutions worked well to change the tips of the white flower petals to vibrant hues while also lightly coloring the rest of the petals. We discovered that our purple solution contained a bit too much blue dye (we did equal amounts of red and blue), so the petals took on a darker blue color rather than purple.

Tips for Making this Experiment a Success:

1. Cut the stems short enough that the flowers are just above the top of the cup (this provides a shorter distance for the water and dye to travel to the petals).

2. Use less water and more dye. The more saturated the dye, the more vibrant the colors.

3. Experiment with other types of white flowers to see if there is a difference in the vibrancy of the colors, the time it takes for the colors to reach the petals, or if some flowers show no change at all. We plan to play around with roses and daisies next.

The Science: Why Does This Happen?

We know that plants need water to survive, and while it is generally the roots that “drink” the water for a plant, even cut flowers can survive for a little while if placed in water. How, you ask? A little thing called capillary action, which moves the water (and anything in it) through the narrow space of the stem via cohesion (water molecules sticking to each other), adhesion (water molecules sticking to the molecules of the plant stem), and surface tension (the intermolecular attraction that pulls molecules of the water inward from the surface resulting in lower surface area). When these forces work together and become stronger than the force of gravity, water, nutrients, and even food dye can work their way up through the plant stem to the petals and leaves of the flower.

We split the stem of this carnation, placing half of the stem in the green dye and half in the blue dye

What Else Can Kids Learn During this Experiment?

Other than capillary action, cohesion, adhesion, etc. (which are pretty high level for our littlest learners), this experiment contains some stealth learning opportunities (my favorite kind!). You have math with the water measurement, stem length, and the number of dye drops. Scientific concepts are covered with learning the colors of the rainbow and learning to mix colors to make other colors. And let’s not forget about art as they take what they see in real life and transfer it to their paper!

For learners who are a bit older, you can use the scientific method to hypothesize what the results will show and draw conclusions based on what you observe over time. You are also throwing in some writing practice as they jot down their observations and conclusions (especially if you use the printable I included to help make this experiment a success).

You can get all of this with a pretty simple experiment that requires very few supplies! What other easy science experiments do you love? Let me know in the comments below!