Pumpkin Life Cycle STEM Activity

Autumn is the perfect time of year to learn about pumpkin life cycles.  You can find pumpkins at farmer's markets, grocery stores, and roadside stands.  And... you can even find them in coffees, teas, bread, pies, soups, muffins, and more!  Since pumpkins seem to be everywhere and in everything during this time of year, it makes sense to incorporate pumpkin life cycles into your science lessons in the fall instead of waiting until spring when other plant concepts are taught. Keep reading to learn about a fascinating pumpkin life cycle STEM activity and popular children's book you can use as a part of your science lessons!

Decomposing Pumpkins Science and STEM Experiment: A STEM and science experiment inspired by the children's book Pumpkin Jack. Learn about the pumpkin life cycles/decomposition. #kellysclassroomonline

Disclosure: Affiliate links to Amazon are included in this post.
All photos in this post are used with the permission of Blakeley Kantor.



Pumpkin Life Cycle

Before starting this STEM activity with your students, it's important to introduce the phases of a pumpkin life cycle to them.  There are many ways to teach these phases, so feel free to teach them in a way that works for you and your students.  Just be sure your students are familiar with these vocabulary words:

  • seed
  • seedling, sprout
  • adult plant
  • vine, blossom
  • green pumpkin
  • orange pumpkin
  • life cycle
  • vine, leaves, roots, stem, blossom

Pumpkin Life Cycle

Other important vocabulary words to review for this STEM activity include:
  • harvest
  • germinate
  • germination
  • decompose
  • compost
  • fungus

Reading Pumpkin Jack

After reviewing the phases of a pumpkin's life cycle, get your students excited by reading Pumpkin Jack by William Hubbard to them.  Pumpkin Jack is about a pumpkin that was discarded outside once Halloween was over.  Throughout the story, readers see the changes the pumpkin went through as it rotted and how seedlings emerged from it in the spring.  Pumpkin Jack is the inspiration for this STEM experiment.

Pumpkin Jack by Will Hubbard

About Pumpkin Jack

Author Summary: The first pumpkin Tim ever carved was fierce and funny, and he named it Jack. When Halloween was over and the pumpkin was beginning to rot, Tim set it out in the garden and throughout the weeks he watched it change. By spring, a plant began to grow! Will Hubbell's gentle story and beautifully detailed illustrations give an intimate look at the cycle of life.

🍎 TitlePumpkin Jack
🍎 Author: Will Hubbell
🍎 Illustrator: Will Hubbell
🍎 Publisher: Albert Whitman & Company
🍎 Date: January 1, 2000
🍎 Pages: 32


Pumpkin Life Cycle STEM Activity

Now that you've introduced the phases of the pumpkin life cycle to your students and read Pumpkin Jack to them, it is time to plunge into this pumpkin science and STEM activity!  

You Will Need


Step One: Getting Everything Set Up

Take the large plastic container and cut a hole large enough to fit your small pumpkin through.  Save that piece.  Add several inches of planting soil to the bottom of the container and spritz with water until damp.  Do not saturate the soil.  Place the pumpkin in the container and replace the top of the container.  You may need to use packaging tape to fasten it in place.

Pumpkin Life Cycle STEM Activity

Step Two: Letting Mother Nature Do Her Thing

Your pumpkin will need warmth and water in order to decompose.  The warmer the air and soil get in the container, the faster your pumpkin will rot.  Place the container in a warm area of your classroom and leave it be.  Don't open it unless you absolutely have to.  Opening it will allow the warm air and moisture to escape from it... which will make it take longer for the pumpkin to decompose.

Pumpkin Life Cycle STEM Activity

Step Three:  Ewww

Throughout the autumn and winter, you will see the pumpkin go through the phases of decomposition.  Fungus and will grow on it and spread to the soil.  As the fungus decomposes the pumpkin, the pumpkin will change colors, shrink, and eventually disintegrate into the soil.  All of this is normal... kind of gross... but normal.

Pumpkin Life Cycle STEM Activity

Step Four: New Growth

Once the pumpkin has disintegrated into the soil, it's time to open the container and let the fresh air in.  (May I suggest doing this outside?  This will be really smelly!)  Cover the remains of the pumpkin and the seeds with planting soil.  Spritz the soil with water until it's damp, replace the top, and wait.  In a week or so, you should see little seedlings emerge!

Pumpkin Life Cycle STEM Activity

Step Five: A Mature Plant

After you see seedlings begin to emerge, you can remove and discard the top of the container.  Keep the container in a sunny window so the seedlings can grow.  Water the seedlings as needed and watch your seedling become mature plants!  

If there are too many seedlings in the container, you can thin out the smallest ones to make room for the others.  Don't throw those small ones out!  You can transplant them into paper cups for your students to grow at home.

Pumpkin Life Cycle STEM Activity

Step Six: Transplanting the Pumpkin Plants

Eventually, the pumpkin plants will outgrow the container they're in and will need to be transplanted.  Depending on the type of pumpkin you used for this activity, its vines can grow up to 20 feet long!  Carefully remove the plants from the container and transplant them into the ground... far away from the playground... or to a raised garden bed.  Continue to water and care for the plants as needed.  Depending on when your school year ends, you may be lucky enough to see some yellow blossom on the plants.

Pumpkin Life Cycle STEM Activity

Additional Resources

🍎 Blakeley Kantor... who took these photos... is an elementary school teacher in Bismark, North Dakota.  If you are on Facebook, you can check out more of her pumpkin life cycle photos.  Special shoutout to Blakeley for letting me use some of them!

🍎 Farmer Christiana from Jones Family Farms talks about the pumpkin life cycle and reads Pumpkin Jack in the video below:



Did you enjoy learning about this pumpkin life cycle activity? If so, check out these blog posts about more STEM projects:


37 comments:

  1. Loved the experiment… just wanted to confirm with you do we have to leave the seeds in the pumpkin while carving or no seeds inside?

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    1. Thanks, Meenakshi! You can really do it either way. If you plan to use the pumpkin for Halloween, save the seeds and put them back in when you're ready to seal the pumpkin into the container.

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  2. I have so many questions, but one is, what is the perfect sized snack jar? I have walmart pick up available but don't want to get something too small!

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    1. That's a good question! As long as the pumpkin fits inside of the container, it's all good. Quite often farmers will sell their runty pumpkins inexpensively because everyone wants the big pumpkins. Buy your container first, then find a pumpkin that fits inside.

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    2. What size container/container source did you use? I have been planning on doing a modified version of this with my toddlers, but so far have been extremely dissatisfied with the largest container I was able to source for this.

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    3. Hi LRose. I recommend using one of the big plastic containers that cheeseballs or animal crackers come in. There is a link in the materials list for an example of what to look for. It's easier to buy the container first, then buy the pumpkin to fit inside it. I hope this helps! :D

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  3. Do you have to carve it for this to work?

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    1. Hi Katie. Thanks for your question. It is possible to do this with an uncarved pumpkin, however, the decomposition process will be slowed dramatically and your students may not see the entire pumpkin life cycle before the school year ends. This science experiment works best with carved pumpkins because the warm air and moisture will be able to start decomposing the pumpkin from the inside as well as the outside. I hope this helps! :D

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  4. We are doing this for our home school my son picked little white pumpkins will that work and can we use a large glass pickle jar

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    1. Good question! I don't know anyone who has used a white pumpkin for this science experiment... we just don't see them often in my area. But if you follow the process in this post, I don't see why it couldn't work. If I find out, I'll reply back to you in the comments.

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  5. I noticed someone used a small container w/a latching lid. Would that be ok??

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    1. Yes! As long as the pumpkin fits in the container and you keep the lid of the container closed tightly, it'll work! :D

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  6. Can I use a glass container? Thanks

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    1. As long as the glass container has a lid that will close tightly, it'll work! :D

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  7. Hi! About how long until I can get to the sprout stage?

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    1. Hi! It can take several months for them to grow. Decomposition can be a long and slow process.

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  8. Hi! I'm doing this in the library with my PK-2nd grade classes. I have one class each day and last week each class per grade decided upon the shape of the cut I made. I'm waiting to put the dirt in after decomposition - Hopefully this works. Kids thought it interesting to see the pumpkin mouths start to "drool"!

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    1. That is a cool idea! Please let me know how it goes... I want to hear about the drooling pumpkin!!!

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  9. will this stink up my entire classroom?

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    1. Hahahaha! Good question! The only way it will stink up your classroom is if you fail to seal it with the tape properly or if one of your students cracks the seal.

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  10. How long did your pumpkin take to decompose, and start to sprout?

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  11. Good afternoon! Our pumpkin is at the stage to be covered, and I just had a couple of questions. First, how much soil would you recommend? And second, there is a lot of "juice" at the bottom. Is that normal?? Thanks!

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    1. Wow! That was fast! My pumpkin this year is still in the decomposing stage.

      When you are ready to add more soil to yours, add between 1/2 and 1 inch. (It doesn't have to be exact.) The 'juice' in the bottom is full of nutrients... don't dump it out! Some people call it 'compost tea.'

      Leave the top off of the experiment to allow some of the liquid to evaporate. Since the soil in the container is already 'juicy,' let your new soil absorb some of that moisture as well. No need to add more water yet. If the soils stays really juicy, you can drain off some of the water to prevent the seeds and seedlings from rotting. At this point, you can take care of your seeds the same way you'd take care of a houseplant. Keep me posted with your progress!

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    2. Okay, perfect! Thank you so much for your reply. :)

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    3. Mine has a lot of liquid as well! I have about 1 1/2" of soil and the liquid is about 1" above that! I hope we can still grow a pumpkin:)

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    4. That's a lot of water! Since you have so much water, go ahead and ladle it out. You want the soil to be moist, not swampy. After you ladle it out, add some more soil to any excess moisture. If you have seedlings, you can leave the top off it and grow it like a houseplant. Good luck!

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  12. When do we know that the pumpkin is ready to be covered with soil? My pumpkin is completely covered in white.

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  13. My pumpkin is not decomposing. It started too but has stopped. The mold that covered the pumpkin has disappeared and it looks like the day we put it in the container other than being black in a few spots. Did I do something wrong? What do I need to do at this point?

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    1. Hi Sherry. Your question stumped me, so I had to google it. As best as I can determine, your pumpkin might have something called black rot. This is what I found so far: "Black rot – One of the more prevalent diseases resulting in pumpkin or squash rotting on the vine is called gummy stem blight, or black rot, and is caused by the fungus Didymella bryonia. This disease is particularly fond of pumpkins and squash, so if your pumpkin fruits are rotting, this is a likely culprit." I'm still googling if black rot will prevent any seedlings from growing. It sounds like you didn't do anything wrong at all. It's possible your pumpkin had traces of this fungus when you purchased it.

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  14. I'm doing this with my second graders and they are loving seeing all the changes so far. We are on stage 3, and watching it decompose is going to be so much fun! My students named our pumpkin, Jack Jr. 😆☺️

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    1. Jack Jr.! I love it! I'm glad you and your students are having fun with this!

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  15. Hi! I am a 7th grade science teacher and we started our pumpkin in August. It is now January and the pumpkin is still decomposing but the soil is completely saturated and very wet. Is this normal? Should I do something to fix it? Thank you so much for any help or advice you can give me.

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    1. Hello! The soil in your container should be moist, but not saturated to the point that there is standing water in it. If there is standing water in your container, it's OK to remove the lid and ladle some of it out. What does your pumpkin look like now? Are there signs of seedlings trying to emerge?

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  16. We never did end up with a lot of white mold... but now have three sprouts quickly popping up... we never added more soil, other than what we started with... can I leave the lid on till we have more growth and put it more in the sun?? we can still see the stem and the skin of the pumpkin, this has been a fun project so far, any further suggestions?

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    1. Good questions! At this point, you can take the lid off, add a thin layer of soil over what's left of your pumpkin, and take care of the seedlings in the same way you'd take care of a regular houseplant... warmth, water, and sunshine. If your room is a bit chilly because of the winter, you can keep the lid the container and move it into the sun to give the seedlings a bit more time to mature.

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