Composting in a jar step-by-step directions! Reduce the amount of food waste that goes to landfills and learn about compost and its benefits!

A composting jar activity is a fun and cool experiment for kids to learn about compost and watch it in action. Kids love to watch and will learn first-hand that composting is very cool! A healthy compost has four elements: Nitrogen, Carbon, Water and Air.

  • Nitrogen (GREENS) Pumpkins, or any food waste!
  • Carbon (BROWNS) Cardboard, Leaves, Wood Chips, Branches

What you need:

  • Two large mason jars (empty)
  • Soil
  • Small pumpkin pieces (or food waste) (NITROGEN)
  • 2 Paper Towel Rolls  (CARBON)
  • 1 Paper Towel Roll  (shredded) (CARBON)
  • Bowl of Leaves (CARBON)
  • Small cup of water
  • Metal Spoon

How to do it?

In one large mason jar, combine soil, 2 parts cardboard and leaves (browns) and 1 part pumpkin (greens), stir. Add water. Stir or shake. Take lid off. Sit on the kitchen counter or window seal and see the compost in action! Continue to stir and once or twice a week. 


Your pumpkin will soon disappear, turning into compost soil –  a nutrient-rich soil conditioner! It takes anywhere from two to four weeks to decompose.

This can also be done with other (greens) in addition to pumpkins and other (browns) items, as seen in the picture such as food items like fruit and veggies,  shredded paper, cotton fabric, hay. 

Landfill Jar Experiment: 

In one large mason jar, combine soil, cardboard, leaves, pumpkin, trash items, empty and crumbled Halloween candy wrappers, bread tie, small plastic lid. Put the lid on and shake. Keep the lid on. 

In a landfill, there is little oxygen.  

This jar acts as a landfill and will demonstrate to your child what the difference is between the two options of ridding of our food waste.

In the jar with the lid, the food will not decompose completely.

(Nor will the leaves, cardboard, and candy wrappers.)

In a landfill, there is little oxygen.  

Compost In A Jar. A link to a more detailed step-by-step of how to compost in a jar with your kids and photos to help you get started. And a list of over 100 things you can compost in a jar! 

You can add an activator to the Compost Jar such as coffee grounds to speed up the decomposition process!