Composting Cardboard: How to shred it ( 3 Simple Ways ) 

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Do you have so many cardboard boxes that you don’t know what to do with them?  

Are you finding it hard to deal with your growing pile of boxes? 

If you care about the environment and want to clear some room at home, consider composting your cardboard boxes. 

 Is shredded cardboard good for compost? 

You’ll be glad to know that cardboard boxes are excellent material for your composting efforts and work just as well as dry leaves, twigs, and branches.  
Be it shredded or soaked, cardboard works as a rich substitute for carbon. In this article, we talk about the different ways you can shred cardboard for composting and more. Let’s get started.  

Do You Really Need To Shred Cardboard for a Worm Bin?  

You can use cardboard for your worm bin, but you need to shred it first. 


Huge cardboard sheets dumped for composting don’t break down. The chunks of large sheets will stick together and form a damp mass.  

This takes longer to decompose which doesn’t serve the purpose of composting. 

Cardboard is great for improving compost because it introduces air pockets.  

These pockets allow oxygen to make its way deep into the compost pile and help the microbes do their work.  

It is important that cardboard should be shredded, for compost to aerate and decompose faster, 

This helps the worms work through layers of organic material, turning them into compost.  

What you get as a result is carbon-rich, well-structured, and abundant nutrient soil that is excellent for planting.  

Is It Better To Recycle or Compost Cardboard? 

While recycling is basically making the most of the product and not wasting the energy that went into manufacturing it, composting takes more time and effort.  

The best way I can put it is this — if it is office paper, it should go into the recycling bin but oiled, soiled, greasy, or wet cardboard should be composted.  

Benefits Of Shredding Cardboard for Compost  

Indeed, shredded cardboard is good for compost.  

Let’s find out why. 

#1. Provides Air Spaces 

Shredded cardboard is a good insulator because of the pockets of air it provides compost. This contributes to the aeration of the compost, leading to microbial action and oxygen in your compost bin.   

#2. Reduces Foul Stench 

Cardboard is essentially brown carbon-rich waste that reduces the foul odor of compost as a result of nitrogen-based green plants.  

By shredding cardboard, you decrease the foul odor and accelerate decomposition. 

#3. Easier Breakdown 

Cardboard can be used as mulch in different composting methods. As long as you do not dump huge chunks of cardboard in your compost pile, it makes it easier to break down.  

What Cardboard Should You Avoid for Compost? 

Are there types of cardboard that you should avoid dumping in your compost pile? We did some digging and here’s what you need to know: 

  • Avoid using cardboard lined with plastic for composting. These include everyday plastic-coated cardboard items like frozen food boxes and milk cartons.  

Why? Because plastic doesn’t disintegrate in the soil and will do more harm than good to your compost bin.  

However, if you use the soak and shred method of composting, then you can separate the plastic sheet from your cardboard since it makes it easier to peel off.  

  • You should also avoid adding greasy, oily pizza boxes and other similar food containers to your compost pile.  
    They not only slow down the composting process but also attract pests and produce a bad odor. 
  • Be careful of synthetic chemicals that come from colored cardboard since they can go into your compost bin.  

Now that you know why cardboard is great for composting and what types of cardboard to avoid, you’re probably wondering:  

How do you shred cardboard for worms? 

 The next section should answer all your questions. 

3 Ways To Shred Cardboard For Composting 

Shredding cardboard for your compost doesn’t have to be a tedious task. However, it’s important to know how to do it the right way to avoid big chunks of cardboard from remaining and not breaking down properly.  

As we’ve already covered, make sure to separate any plastic from the cardboard. Keep an eye out for plastic-coated cardboard like the ones found in milk cartons, frozen food boxes, and paper cups.  

These are usually lined with plastic to ensure they do not leak. If you make the mistake of shredding one into tiny pieces, it’s going to take time to pick them out. 

To prepare your cardboard for composting, there are multiple ways you can go about this. Consider which of these methods will work best for you: 

1. The Typical Shredding Method 

The Typical Shredding Method for Cardboard composting
You can also use Scissors to shred cardboard

Before you get started, you’ll need to make enough space to work and accommodate your cardboard boxes. Having an established work area will make your job easier.  

  1. Sort your cardboard ensuring that any plastic (including tape) attached to your cardboard is removed. 
  1. Settle into your work area with the cardboards for composting. If you don’t have a box cutter yet, you can use a pair of scissors.  
    For the long-term, however, consider upgrading your setup with a box cutter since it cuts through cardboard more smoothly and more quickly. 
  1. Take the box cutter (or scissors) and cut along the cardboard’s corrugation lines or creases cutting until they all measure roughly 8 inches (or roughly about 21cms).  
  1. Once all pieces are about the same, smaller size, continue shredding them into smaller strips or feed them into an electric shredder.  
    While there are many shredders online, a good one for composting is a model that will cut through many sheets.  
    My personal favorites are the heavy-duty shredders that can slice 24 sheets at a time. 

2. The ‘Soak And Shred’ Method 

For those who want to avoid all the cutting and shredding from the first method, the wetting method, also known as the soak and shred method, is very simple.  

All you need to do is soak the cardboard in water. Soaking softens even large pieces of cardboard and makes them easy to tear with your hands.  
The longer you soak them, the easier they are to shred. If you want to make sure they’re really soft, you can soak them in an unused tub for two to three weeks. By that time, they will be very easy to tear. 

This is a handy method for those who live in rainy climates. Just leave them outside to soak up the rainwater.  
When they’ve soaked up enough water, simply pick them apart and lay them in with your compost. This method also works for making peeling plastic off easier.  

3. The Lasagna Method 

The Lasagna Method using cardboard for composting
Cover the ground with a layer of big cardboard

Green thumbs and long-time gardeners may already have an idea of what this method is about.  
Otherwise known as sheet composting, this age-old technique entails laying down a layer of moist cardboard and building up layers like you would lasagna. 

Once you’ve laid down the initial layer and the mulch starts to decompose, add a second nitrogen green waste layer on top.  
Keep alternating the layers of your garden lasagna with layers of nitrogen-rich green material. Let it sit until the layers are cooked down. To speed up decomposition, water the topmost layer and sprinkle it with old compost material. 

How Long Does the Lasagna Method Take? 

The lasagna method will take three to six months to break down. Later, you can remove the pieces of plastic left on your cardboard packaging.  

If you want to get the best results, remove all plastic stickers and tape before you begin

Lasagna gardening results in nutrient-rich soil from organic materials that will help your plants thrive as the layers decompose and become compost.

This planting technique can also help you convert a lawn into a planting area.  

Don’t forget: cardboard also works as a great weed barrier while helping with water retention. 

If you have tons of cardboard!

the easiest way to shred cardboard for compost is to consider using a chipper shredder  

The Chipper Shredder Solution 

Using a chipper shredder is the easiest, quickest, and most convenient way to make your boxes compost-ready.

Not only can chipper shredders cut cardboard, but they can also work their magic on twigs, leaves, pine needles, and branches.

They’re particularly useful for larger, stiffer pieces of cardboard that your paper shredder can’t handle.  

Can a garden shredder shred cardboard?

If you have a garden shredder at your disposal instead of a wood chipper, then you can use this tool as well.  

Additional ways using Cardboard for Composting 

Aside from shredding your cardboard into tiny pieces and dumping them into your compost, did you know that there are additional ways you can use them for your compost?  
That piece of cardboard gathering dust in your garage could act as an insulator for colder months as well as a blanket to keep your worms happy.  
Let’s find out more, shall we? 

Cardboard as an Insulator 

Insulating your compost pile during the colder months is a must.

You can do this with bubble wrap or styrofoam boards, but corrugated cardboard works just as well since the corrugated pattern traps air within and adds heat to your compost. 

When it’s done keeping your compost warm, the cardboard will eventually break down and mix with your pile.  

Cardboard As A Makeshift Worm Blanket 

This makeshift cardboard worm blanket keeps the light out and the warmth and moisture in, ensuring your worms are happy. 

Composting: A Double Win 

Composting at home using materials like cardboard is a very satisfying DIY project.

After all, you’re not only making good use of otherwise useless materials, you’re helping Mother Earth while you’re at it too.  

Once you’ve done it once, the rest is easy.  

Happy composting!