Cardboard can be safely added to compost piles, compost bins worm farms or as the base of your no dig garden. Cardboard can be composted if it is plain, tape free and does not have a shiny coating. The best types of cardboard to use in your compost are plain pizza boxes, cereal boxes, packing boxes, shoe boxes and food grade cardboard.
This article will explore the top 10 types of cardboard you can use in your compost bin or even shred to use as worm farm bedding. Check out the top 10 cardboard types you can use in your compost.
1. Amazon boxes
Plain, brown cardboard is the best type to use in your compost bin and Amazon boxes are perfect. They have minimal ink which breaks down fast and will not cause harm to your soil. Break down the boxes into small pieces by tearing them up or cutting them with kitchen scissors.
If you can tear them up into strips then they will break down into the soil fast and help you to make compost quickly. Recycle Amazon boxes in your or flatten them out to make a new no-dig garden bed.
For more how to make a no-dig garden bed with cardboard check out my article here: How long it takes cardboard to break down in soil (Guide for No Dig Gardens)
2. Cardboard without tape
It is essential to use cardboard in your compost without tape. Packing boxes will usually be covered in tape so remove it all before you compost it. Many boxes will be stuck together with glue without tape but double check before you put them in your compost.
The plastic tape will not break down and you might be digging it out of your soil for years.
3. Plain cardboard
Any plain cardboard box can be used in your compost. Remove the tape and the staples and tear it up into smaller pieces. You can cut it up with kitchen scissors to help it to break down fast. Mix it through your compost bin and add some food scraps or used ground coffee to add extra nitrogen and moisture.
Remember to keep your compost bin around 1/3 green material like grass clippings, food scraps and coffee grounds with 2/3 brown material like cardboard, sugar cane, straw and fall leaves.
4. Pizza boxes
Pizza boxes are great for adding to your compost bin. Make sure that there is not any excessive amounts of cheese or meat in the box as this could attracts rats or mice. They are easy to tear into pieces and can even be added to your worm farm.
The smaller your pizza pieces are, the quicker they will break down. This is a great way to recycle them in an easy and fast way.
5. Cereal boxes
Cereal boxes can be cut into pieces and added to your compost. Make sure the cardboard is not plastic coated by tearing it in half. You should be able to see plastic on the edges if there is a coating. Most cardboard used for cereal boxes will not be plastic coated and they are food grade.
The cardboard is thin and breaks down fast in your compost if it is mixed through and in contact with the other materials. Soil bacteria will break it down and digest it fast.
6. Packing boxes
Packing boxes are my favorite cardboard to use in my compost and garden. They are great for lining the base of a new no-dig garden bed and will take 2-3 months to break down. Packing boxes will break down faster in your compost if they are torn up and the pile is mixed regularly. This adds oxygen and support the bacteria to break it down faster.
7. Shoe boxes
Shoe boxes are really good for adding to your compost. As long as the cardboard is not shiny or plastic coated it will be fine. My kids seem to need a new pair of shoes every 2 months. We always have shoe boxes hanging around. You can use them to store your seeds or break the carboard down into compost to feed your soil.
8. Food grade boxes
Any cardboard that has carried fresh food like fruit or vegetables will be considered ‘food grade’ and will break down fast. It should be plain, without any printing or stickers. Check there is no tape and you are ready to add them to your compost.
Cardboard that holds fruit in place in displays will be rounded and soft and easy to tear. Soak it in a bucket to help to hydrate it and it will break down fast and mix through easily.
9. Egg cartons
Egg cartons are great to add to compost bins and worm farms. Worms will hide in the egg carton holes and will slowly digest the cardboard and the soil bacteria. Egg carton are soft and easy to tear so break them into single cups or just break them into 3 pieces and mix it into your garden bed. You can use them to top your worm farm and protect them from birds.
10. Toilet rolls
Toilet rolls are small and great for your compost. I add them to my compost and worm farm bin but I will chop them into strips first. This will allow them to almost dissolve into the compost fast and you won’t even know they are there.
11. Paper towel rolls
Paper towel rolls can be added straight to your compost or cut them up into pieces first. Some of the larger rolls will have thicker towel rolls which will take longer to break down. If they are thick, soak them in water before adding to your compost bin.
Types of Cardboard You Can Add to Compost | Summary
Carboard is fantastic to add to your compost bin and will add valuable carbon to your soil. Avoid adding carboard to your garbage and return it to the soil instead. Avoid adding cardboard with a plastic coating, tape or stapes. Soak the cardboard in water before adding to your compost to help it to break down faster.
I am an accredited practicing dietitian, experienced gardener and a dedicated cook. I love writing and sharing my experience so you can learn from my successes and mistakes.