Christmas STEM: Poinsettia pH Experiment

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I have been having a lot of fun this season doing lots of different Christmas science experiments. This past week we tried a cool Christmas STEM project. We tried out a poinsettia pH experiment. You know that classic cabbage juice experiment? You can do the same thing with poinsettia leaves!

What Is the Poinsettia pH Experiment?

The Poinsettia pH experiment is so fascinating! If you have never done one of these pH experiments, let me explain how it works a little bit.  If you took chemistry, you may know the terms acid and base. Acids have a low pH and and bases have a high pH. They are like opposites. pH is a measurement of the hydrogen ion concentration in something. It stands for power of hydrogen. Some substances are neutral, like water.

You can measure the amount of pH in something by using an indicator. Cabbage juice is the common indicator used in experiments, but Poinsettia leaves also work! The indicator is a chemical that changes color when in comes in contact with an acid or a base. The color it turns tells you whether it is an acid or a base.

Why does this happen?  The red leaves of a poinsettia contain anthocyanin, a chemical that changes color when mixed with an acid or a base. There are quite a few different plants that contain this chemical, including blueberries, raspberries, and other red, blue and purple plants. It is present in leaves in the fall when they change colors, too.

How to Do the Poinsettia pH Experiment?

It is really quite easy to do this experiment!  You pull off a few of the red leaves of the poinsettia and cut them into pieces.

Cover them with water and boil the water. You can do it on the stove or in the microwave to save time. Once the color is released from the leaves and the water is a purplish color you are read  to use it.

You can use coffee filters or other tissue paper to make homemade pH indicator strips with the poinsettia “juice”.  Saturate the coffee filter in the liquid and let it dry completely.

Once it is dry, cut it into strips. and it can be used to test the pH of any substance.

We tried a few different things including lemon juice, water with baking soda mixed in, salt water, cola, soapy water, and vinegar. We love using our little test tube set for this!

Take a few drops of each liquid and drop them onto the indicator strips. The strips will change colors based on the level of pH. Eye droppers or pipettes work great for this.

You can see how ours turned out here:

Cool, right?! Try it out with your own poinsettia plant!

See More Fun Christmas Learning Activities:

Christmas Science: Grow a Crystal Tree
Christmas Pattern Block Templates
Christmas STEM: Rudolph Pipe Cleaner Circuit
Christmas STEM: Gingerbread House Paper Circuits
Christmas Mad Libs Printable Worksheets

Want even more Christmas STEAM ideas?  Check out  the STEAM Kids Christmas book!  You will not be disappointed!