By Lauren Click, Founder of Let’s Go Compost

Ready to embrace the Halloween spirit? Explore decomposition and composting in this pumpkin-packed STEAM (science, technology, engineering, art, and math) experiment the whole family can enjoy until the spring!

Tools Needed:

• One Small Pumpkin
• Carving Tools
• A Large Glass Jar and Lid
• Potting Soil
• Packaging Tape

Step One: Preparing Your Pumpkin

Add 2 to 3 inches of moist potting soil (about the consistency of a wrung out sponge) to the bottom of your jar. Then, pick a design, carve your pumpkin, and be sure to leave the guts inside the pumpkin (especially a few of those seeds). Place your pumpkin into the jar. If your lid is not air-tight, use tape to secure the lid in place and place the jar in a sunny windowsill. 

Step Two: Let Mother Nature Do Her Thing

Since your pumpkin is a living organism, microorganisms like bacteria and fungi will soon begin to break down the pumpkin’s cells inside the jar. The warmer the container, the faster it will rot. Be sure to not open the jar to keep the moisture inside! Your pumpkin will soon soften, change color, and decompose. Encourage your kids to take weekly pictures of their jar to track its transformation.

Step Three: Waiting Through Winter

Throughout the fall and winter, watch the pumpkin go through the phases of decomposition. Fungus will grow on it and spread to the soil. As the fungus decomposes the pumpkin, it will eventually disintegrate into the soil!

Step Four: Getting Seedlings for Spring

Once the pumpkin has disintegrated into the soil, open the container and let the fresh air in! Do this outside, as the anaerobic environment inside the jar can be smelly. Add two to three more inches of moist potting soil. Replace the lid (no need to seal with tape) and, in a week or so, you should see seedlings emerge!

Step Five: Preparing Your Pumpkin Plant

Once seedlings emerge, remove the lid to the jar. Keep the container in a sunny window and the soil moist. Thin out the seedlings to remove the smallest ones. Eventually, the pumpkin plant will outgrow the jar and must be transplanted into a garden bed – its vines can grow up to 20 feet long! Continue to water and care for the plant. As summer begins, you should start to see yellow blossoms on the plant that will turn into a brand new pumpkin you can enjoy next fall, completing the cycle of life. 

And there you have it! A fun, family-friendly garden experiment that shows off the decomposition process with tools you can find at home. Want to learn more about composting? Let’s Go Compost is a 501(c)(3) non-profit on a mission to make composting free and accessible! Visit LetsGoCompost.org to find more STEAM composting experiments for kids of all ages and to learn more about composting.

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