What Cardboard Can Be Composted

You tried to sell your cardboard, re-using it, and gifting it to friends.

However, you can’t get rid of those last couple of boxes.

What now?

Any cardboard can be composted as long as it hasn’t been contaminated by things like clean products; the main types of cardboards which can be composted are corrugated cardboard, flat cardboard, and wax-coated cardboard.

Although the latter one, being wax-coated, is much harder to compost than the rest since it has been lined with another material like wax or non-degradable foil lining.

So, if you’ve got a pair of green thumbs and you’re sitting on a lot of cardboard after moving from one home to another, or you’re just a serial cardboard collector, then you’ll be happy to know, yes, most cardboard can be used for composting.

Though before you run off and dump your remaining cardboard into your compost heap, let’s delve a little deeper into cardboard composting so you can understand why this is.

What is composting?

Composting is the natural process of recycling organic waste, such as leaves, unwanted food, or even cardboard into a fertilizer that can be used to enrich your garden soil to help plants to flourish.

Anything that grows will decompose eventually when given enough time, composting just helps to speed up this process by providing the waste materials with the ideal environment it needs to go through this process; decomposing organisms like bacteria and fungi help to produce this dubbed ‘black gold’.

Why composting cardboard is a great idea

As someone with green thumbs, you’ll know that at a certain time in the year, you’ll find yourself with more “green” compost materials and very little dry “brown” material, such as dry leaves, twigs and branches.

And as you know, a good composting pile requires that you have both to help balance the mixture.

If you live in a more urban or city area, coming across these materials can be quite difficult if they are not already in your own garden, so something like cardboard is going to be the ideal material to use instead.

How to prepare cardboard for composting

Breaking down your cardboard boxes is not going to be good enough if you’re wanting to use them for composting, you’ll need to break it down into much smaller pieces so the fungus and the bacteria can work their magic.

Make sure to shred your cardboard first

If the cardboard is not shredded, large sheets will stick together in a big damp mass and will take a LONG time to decompose, which of course defeats the whole purpose of intentionally composting materials.

Shredding your cardboard will allow it to have a much more efficient structure so that air circulates properly and the decompose time can be much faster.

Ideally, you’re going to have a shredder on hand to do this, as tearing cardboard into long strips is going to be very tedious and boring after the first couple of boxes.

Though there are some other methods that can make life much easier if you don’t have an electric shredder on hand…

The Wet Method

This is a pretty simple method, you just want to soak your cardboard in water so it’s much easier to tear into strips.

Depending on how much cardboard you have and its size, you have a couple of ways you can easily achieve this.

One way you can do this is you can leave your cardboard outside for a week or so if you live in a rainy climate since this will begin the decomposition process which will make your cardboard much easier to break up.

Alternatively, you could leave it to soak for up to 2 weeks in a tub, though of course, it goes without saying we wouldn’t suggest putting the cardboard in your bathtub…unless you want to go weeks without bathing.

However you choose, once the cardboard is softened, it becomes much easier to shred.

Lasagna Method

Lasagna gardening is a slow compost process that requires little effort compared to the other composting methods.

The method begins by laying down sheets of cardboard that have not yet been shredded which then get composted into the underlying soil and vegetation; alternating layers of nitrogen-rich green materials and dry carbon-rich waste.

You can use this method in your own compost heap by creating alternative layers of cardboard, green and brown organic waste, whilst sprinkling a bit of water on every layer as you go.

With this method, you can even leave the plastic tape/sellotape on the cardboard packing and simply remove it when everything has been broken down.

Don’t forget to remove any plastic/sellotape

We’ve mentioned a couple of times about removing the plastic and the sellotape from your cardboard before you use it in your compost heap, and this is for good reason.

This is simply because this material does not break down as well as the other materials in the heap, so removing it just removes this issue.

As mentioned in the lasagna technique, you can leave the sellotape attached because this method takes a lot longer to break down than the typical composting method, so it isn’t going to cause any problems in the future.

Tips to compost cardboard

So, as we now know, it’s critical that you shred your cardboard before attempting to put it through the composting process unless of course, you are using the lasagna method as we’ve just outlined previously.

With this being said, here are some tips on how to compost cardboard properly.

  • Begin your compost pile with cardboard first: This will create a sturdy bottom layer, you should also include other high-carbon materials like straw and hay.
  • Add a 4-inch layer of nitrogen-rich materials: this can include things like fresh grass, cow manure or vegetables that didn’t quite make it to the stew.
  • Add 2-inch layer of soil on top of the last
  • Continue on until you have a pile of 4 cubic feet: It’s crucial that this large pile of compost is kept as moist as a sponge, so add more water or cardboard depending on how wet it feels.
  • Turn the compost pile every few days – Turning the compost pile every so often will help to speed up the decomposition process.
  • Additional tip – Soak cardboard in water: This will help to speed the composting process up slightly, so it can break the material down faster and give you that ‘black gold’ much faster.

As you can see, getting your carbodard into the composting heap is pretty easy, which means you’re going to have less waste around the home and more useful black gold that your plants and flowers will be thankful for.

Can be composted

You can’t JUST use cardboard on your composting heap, since the concoction of materials isn’t going to be the ideal place for things like bacteria to work their magic, as we’ve already mentioned.

With this being said, you’re going to need to add other materials to the pile so you can create this ideal scenario and also allow you to use even more of that household waste for good, rather than letting it pile up in a landfill somewhere…

  • Grass clippings
  • Tree leaves
  • Vegetable Food scraps
  • Coffee Grounds
  • Newspapers (black and white)
  • Printer paper
  • Disease-free yard waste
  • Vegetarian animal manure, such as cows, horses, rabbits, hamsters.
  • Wood shavings or sawdust

Can be composted, but are a little bit more complicated…

There are some items you can put in your compost heap, but they’re a little bit more complicated – we’ll tell you why…

  • Non-vegetarian manure – Manure from animals that eat meat, such as dogs and cats, CAN be composted, but may contain pathogens that can spread disease, and ruin your whole composting heap.

To solve this issue, you need to make sure your compost heap gets hot enough to kill off these microbes.

With this in mind, we would recommend you stay away from this type of manure if your compost heap is not going to get this hot or you just simply don’t want to have to worry about your compost pile being ruined by something that could have been easily avoided.

  • Noxious Weeds – while weeds like creeping charlie are more than safe for your compost heap, they can actually thrive in this environment, which means once you’re using your black gold on your flowers, they may get in places where you don’t want them.
  • Food scraps – whilst food scraps are great for your compost pile, they can cause you an unwanted pest problem which could do a lot of damage to the rest of your garden. However if you’ve got a compost bin that locks, then we can still confidently recommend that you use this type of material in your heap.

Cannot be composted

So, there are some great things you can use as compost, some not so great things and now we’re going to go over some things that DEFINITELY SHOULD NOT be used in your compost heap.

  • Diseased yard waste – Do not use dead or diseased plants in your compost pile. Whilst yes, they can be broken down, as all living things can, they do not get rid of their disease once they have died, which means they could infect any and all plants that are eventually going to come into contact with the compost.
  • Meat, fat, and bones – These types of waste foods are an attractive meal to many animals who would more than happily destroy your compost bin to get to them, which will of course ruin the whole compost pile. On top of this, these types of food products can very easily carry disease, which as discussed will infect any and all garden life it could come into contact with.

Advantages of composting

There are more advantages to composting beyond just getting yourself some black gold. Let’s review what they are BEFORE we get into some of the disadvantages of composting…

  • Reduces landfill – One of the main reasons why composting is a good idea is because yard and food scraps make up 25-50% of what we as humans throw away. So instead, it’s much better for us to use this waste as great compost which can be used as fuel in our own gardens, rather than allowing it to pile up in a landfill somewhere.
  • Creates nutrient-rich soil – As gardeners, we love the fact that composting creates nutrient-rich soil our plants and flowers are going to absolutely love.
  • Reduces greenhouse emissions – One of the biggest contributors to greenhouse gases, due to the methane in the materials, is from our landfills; so if we were to use these materials in our compost heaps instead, we could drastically bring these emissions down.
  • Positive effect on air quality – Many of the people that don’t use their yard waste in their compost heap, instead, set it a light as a way to get rid of it. Which negatively affects the surrounding air quality, which could lead you to have health problems in the future, such as asthma.
  • Great at combating garden pests – The nutrient-rich compost has many micronutrients that have pesticide-like effects on those garden pests we all know and hate. So having compost on our gardens reduces the need for harmful chemical pesticides we’d typically use.
  • Neutralizes soil – In many cases, which you may be familiar with, some soil is far too acidic or basic for plants to grow and thrive properly, but when you add compost to this soil, it helps to regulate the acid and alkaline levels.
  • Increase the biodiversity – Compost attracts different kinds of worms, bacterias, birds, and even fungi, which are all beneficial to the crop growing process.

Disadvantages of composting

  • Requires initial investment – Composting needs some huge upfront investment when it comes to getting the materials in the pile just right. On top of this, you’re also going to need the required materials before you begin, which you might not yet currently have – which is obviously not ideal if you’re desperate to get the black gold as soon as possible.
  • Requires monitoring/upkeep – Once you’ve put in the initial effort, you can’t just leave your compost and let it do its thing for the next couple of months, you need to make sure that it is actually going through the process properly. This means you might need to add more waste to the pile – something you’re only going to find out if you’re constantly checking in on it.
  • Unpleasant smell – the fact is, a compost pile has a very unpleasant smell to it because at the end of the day you’ve essentially piled up a bunch of waste which you’re putting through a decomposing process.
  • May attract rats and bugs – Since you’re adding a lot of food waste to the pile, this will of course attract unwanted pests like rats and bugs to your garden, though this issue can be solved if you have a compost bin in your yard.
  • Doesn’t look very appealing – Unless it’s hidden inside a compost bin, a compost heap doesn’t look too appealing, which could really mess with the aesthetic of your garden which you might have put hours upon hours of effort into.
  • Composting process takes time – The fact is, going to the garden store and buying a bag of fertilizer is going to be a lot faster than it is to make your own compost to use as fertilizer.

Worm farming and cardboard

Worm farming is the process of harnessing earthworms to convert organic waste into nutrient-rich fertilizer, which is full of minerals, nutrients and beneficial microorganisms which are essential to any plant’s healthy growth cycle, root development and disease suppression.

Worms are cardboard lovers too

One of the materials which is utilized the most for worm farming is brown cardboard since these earthworms go absolutely crazy for it.

It’s the perfect material for bedding and it’s the most readily available food stock, since they can effectively eat every last piece of cardboard around them

On top of this, corrugated cardboard, which is one of the most common types of cardboards is held together by glue and this glue is made from cornstarch which is absolutely full of nutrients.

So this might be one of the key reasons as to why worms love brown cardboard so much.


We’ve discovered that pretty much any cardboard can be composted, as long as it has not come into contact with any contagious substances like cleaning products.

And we’ve also outlined the pros and cons of composting and why you should be utilizing your cardboard in your garden instead of sending it to the landfill.


Father of two who hopes that by sharing the things he learned, he can leave the world behind slightly better than he found it.