Is Cardboard Compostable? Yes! Here’s How!

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Yes, you can compost cardboard, but there are several things to consider before doing so.

Some cardboard people want to add to their composter may have issues such as greasy pizza boxes or cardboard with ink printing.

Knowing the right way to deal with these concerns is why I wrote this quick guide to composting cardboard. 

Once you know the tricks to compost different types of cardboard, you can continue to help the environment by reducing household waste going to landfills, and improve your plants in the process!

Can You Compost Cardboard?

Now that you know you that cardboard is compostable, let’s take a look at the variety of items you can use, such as:

  • Plain brown cardboard from shipping boxes
  • Cardboard with ink from packaging
  • Cardboard egg cartons
  • Pizza boxes or takeout food boxes
  • Cereal boxes
  • Rolls from toilet paper or paper towels
  • Shiny colored cardboard from product packaging
  • White or bleached cardboard

I personally add any and all types of cardboard to my traditional compost bin with the exception of very greasy pizza or takeout food boxes. You can compost pizza boxes, but my personal preference is just to recycle them.

I still compost that material but choose to add that material to my vermicomposting bin since the worms seem to love it.

Related | Best Worm Composters

Some people find cardboard that is bleached white with heavy ink printing or has a shiny surface disconcerting to add to their compost. The fear is contaminating the finished compost material with chemicals or dyes that could harm plants.

Luckily, it would take a tremendous amount of inked or altered cardboard in your compost to cause concern. Choosing to add or not add these types of cardboard to your compost is genuinely a matter of personal preference.

The average household can add in bits of any cardboard they may collect over time, but do be aware that paperboard with shiny surfaces takes longer to break down.

Pros And Cons Of Composting Cardboard

Like any ingredients that you add to your compost, you need to consider the pros and cons to determine if composting cardboard will work well for you.

Pros

  • Cardboard is rich in carbon, which feeds compost microorganisms
  • Reduces waste going to the landfill
  • Increases aeration within the pile
  • Insulates to retain heat inside the compost
  • Balances high amounts of nitrogen ingredients
  • Free and abundant “brown” material
  • Soaks up excessive moisture
  • Excellent bedding for vermicomposting systems
  • More efficient than traditional recycling in terms of energy use

Cons

  • Stacks of cardboard can add up fast, taking up valuable storage space
  • Needs to be torn or shredded for optimal use
  • Need to remove tape and staples
  • Wax-coated or laminated cardboard take longer to degrade
  • Colored cardboard may leave dye or chemical residue behind
  • Needs to be mixed well with green ingredients for best results

The only real problem I face when composting cardboard is the sheer amount of material I gather on a weekly basis, even when I do my best to reduce purchases that have excessive paper packaging. 

When I have time, I like to shred as much cardboard as possible. I keep it in a lidded aluminum trash can, which reduces storage concerns and is handy to grab handfuls to add to my various compost piles and bins.

How Long Does It Take For Cardboard To Decompose?

Composting with cardboard isn’t much faster than using, for example, mostly dried leaves as a brown ingredient if you build your pile incorrectly. 

Expect it to take three months to a year, depending on how well you tend to your pile.

Cardboard does quickly disintegrate if you can keep the material continually moist, which will speed up the time it takes to create useable compost.

Other factors will increase or decrease the decomposition process.

How To Compost Cardboard

For the best results, when composting cardboard, follow these steps:

Step 1 – Remove Uncompostable Items From The Cardboard

Much of the cardboard on packaging or shipping boxes have tape, stickers, or staples that won’t break down within your compost.

Take a few moments to remove these items, so when your compost finishes, you don’t spread sharp staples or ugly plastic tape remnants about your garden.

Step 2 – Tear, Cut, Or Shred Cardboard Material

For speedy decomposition within the compost, reduce sheets of cardboard into as small of pieces as possible. Many paper shredders can handle the thickness of cardboard, which saves a ton of time over manually tearing it up.

Step 3 – Add The Cardboard To Your Compost

Spread a layer of cardboard onto your compost in a proper amount to offset or balance the number of green ingredients. Add a bit more if the compost seems overly wet since the cardboard will soak it up and help reduce odor.

For new compost piles, start with a four-to-five-inch layer of cardboard, then layer up green and brown ingredients over time, keeping ratios in balance.

Step 4 – Mix The Cardboard Into The Compost

For optimal speed when composting cardboard, turn the pile every three to five days. If you see the cardboard shreds drying out, moisten the material and mix some more.

I find that turning the cardboard into the compost material very well with a pitchfork keeps the cardboard from sticking together.

When the cardboard mats up, it can reduce the amount of moisture and airflow within your pile, wreaking havoc with the internal temperature and slowing down microorganism digestion.

TIP: As long as you maintain a regular compost turning schedule, leaving a layer of cardboard on the top of your compost pile can help retain heat during colder months. A thick layer can also act as a barrier to keep critters away from the food scraps.

In Summary

EPA statistics show that paper and cardboard packaging make up 23 percent of landfill waste. Doing all you can to recycle cardboard by turning it into compost is helpful to the environment, reduces strain on local waste-collection services, and brings valuable nutrients to your garden.

I hope you use this guide to begin composting household cardboard instead of tossing it into the garbage.

Now that you know cardboard is compostable and see that the benefits far outweigh the negatives, you can enjoy your breakfast and feel good about composting those cereal boxes!