Erupting Mini Pumpkin Volcanos

Kids will never get tired of baking soda and vinegar science experiments. They are just plain easy and fun for our budding scientists!

Pumpkin Volcano Green Lava

When I took out the mini pumpkins and baking soda, my son knew immediately what we were doing. After all, he had tons of fun with the LEGO volcano and the apple volcano experiment. I think by now he thinks we can put baking soda inside anything and make it erupt “lava” … and why not!

This erupting mini pumpkin volcanos experiment is a perfect STEM activity for the fall and Halloween season. You can certainly do this science experiment with a bigger pumpkin, but I like the little ones because each kid can get his own!

How to Make a Pumpkin Volcano


  • Mini pumpkins (I got mine at Trader Joe’s, but you can also visit local farms or pumpkin patches for them)
  • Baking soda
  • Vinegar
  • Optional: Dish soap
  • Optional: Food coloring
  • Dropper 
  • Small cup or bowl 
  • Plate or tray to catch the “lava”
  • Knife


1. Cut the stem off with a knife (adult only please!). Make sure you cut at an angle so that the lid doesn’t drop inside the pumpkin.

Pumpkin Volcano Carve Pumpkin

2. Scoop out all the pulp and seeds. 

3. Fill the inside of the pumpkin about halfway with baking soda. 

Pumpkin Volcano Baking Soda

4. Optional: For a more foamy eruption, add a few drops of dish soap to the baking soda.

5. Optional: Add a few drops of food coloring to the baking soda.

6. Place the mini pumpkin on a tray or plate.

7. Pour vinegar into the small cup or bowl.

8. Use the dropper to suck up the vinegar and squeeze it into the mini pumpkin.

Pumpkin Volcano Dropper

9. Watch the “lava” erupt out of the pumpkin volcano!

Pumpkin Volcano Black Lava (2)

The kids had a blast with the pumpkin volcano experiment and wanted to do it over and over again. All you have to do is wash the inside of the mini pumpkins out with water and they are ready for more explosive action! 

We did the experiment once without any food coloring and once with green food coloring. The green food coloring reminded us of a witch’s brew but inside a pumpkin instead of a cauldron. You could paint the pumpkin black with acrylic paint to make a fun witch’s cauldron STEM activity!

Pumpkin Volcano Green Lava (1)

I told the kids to pick their favorite food coloring and of course, they wanted to use them all. The result was a blackish mixture of colors that looked spooky when flowing out of the pumpkin. Well, it is a Halloween science activity after all!

Pumpkin Volcano Black Lava (1)

We tried adding the top to the pumpkin while the foam was coming out to see if the foam would stop. Nope! The little pumpkin lid was not heavy enough to stop all the bubbling action.

Pumpkin Volcano with Top

Science Behind the Pumpkin Volcano

When you mix baking soda and vinegar together, a chemical reaction occurs. The result is carbon dioxide gas that rises to the top of the mixture. 

Even when you don’t add dish soap, you will see a lot of bubbles and foam from adding vinegar to baking soda. The dish soap just produces even more bubbles and makes the eruption even more exciting!

Pumpkin Volcano Black Lava

For more fun Halloween activities, check out:

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