That cardboard you’ve been throwing off to the compost heap or in the trash bin could serve a better purpose if you shred it for compost.
Also, did you know that even though paper recycling is touted as being environmentally friendly, there are often some drawbacks? Paper manufacturing uses up to 10 liters of water for every A4 sized paper. Paper recycling factories also end up with a lot of toxic sludge that’s tough to eliminate.
Plus, these factories consume more energy than paper mills, meaning they burn more fossil fuel. As such, composting paper and cardboard is a better way of disposing of paper waste because you’re also using it to create a useful soil amendment for gardens.
Therefore, if you have some cardboard laying around in the confines of your garage, make sure you use it to add the much-needed carbon your compost needs.
Upside of using cardboard for compost
The compost obtained from shredded cardboard boxes has its unique advantages.
The cardboard gives the compost mix a solid structure and it guarantees that your compost is better aerated, and that decomposing bacteria have a consistent supply of oxygen to thrive.
The downside is that, unlike dried leaves, which break down quickly, cardboard takes up a bit longer to decompose.
Shredding cardboard can also be tough if you have a lot of it, and rigid cardboard boxes may need more time, though you can always make things easier by wetting the paper first, which will make it easier to cut, especially through the corrugation lines.
Preparing the cardboard for composting
Sometimes during the year it’s a bit difficult to find dried leaves.
So, often, the solution is back in the house – that heap of cardboard boxes lying in the corner waiting for you to pick them up.
With that being said, even if you have leaves, you’re also free to blend the cardboard with dried leaves (or other foliage) available to create a more diverse compost heap.
Types of cardboard you can compost
Not every paper box is suitable for composting, but 9 times out of 10, most of the cardboard you have at home is compostable.
Let’s look at some examples of compostable cardboard.
Corrugate cardboard boxes from Amazon or Aliexpress
Whether it’s an item you shipped from Aliexpress or a mobile phone you purchased from a store downtown, corrugated cardboard makes up the packaging.
The grooves make it tough and more rigid, so you need to chop it down thinly before throwing it into the compost.
This is the type of cardboard box that is most composted by gardeners.
Flat cardboard from that boxed juice or wine
Some items such as shoes and drinks come packaged in flat cardboard boxes.
Given that the cardboard is usually lined with a shiny waterproof material on the surface, you’ll need special handling here.
Peel off the plastic cover to expose the paper before shredding the cardboard. You don’t want to leave the plastic as it can take months or years to compost plastic-lined cardboard, even if it has been finely chopped.
Wax coated cardboard (not all)
Laminated cardboard from paper cups and pet food bags can be composted. Since the wax coating is known to retard water absorption, expect these cardboard materials to take longer to break down.
You can also use other types of paper. If you have plain paper, paper towels, tissue paper, plain paper books, or even newspapers, those are also compostable.
Shredding the cardboard into small pieces
To sum up the importance of shredding cardboard for compost:
Shredding cardboard aids in the composting process by reducing the size of the cardboard and increasing the exposed surface area.
Ultimately, the breakdown process is quickened, so you can have your compost ready at the desired time.
I’ve mentioned that cardboard adds to the compost structure and density as it breaks down. The processed paper is also a great source of carbon, and provides decomposing bacteria with more room to breath, as well as energy.
However, these benefits are more easily achieved if you shred your cardboard into small pieces. Shredding the cardboard will also make it easier for you to add it to your compost, and consequently facilitate having to turn the compost manually.
Allow me to share with you some tips for shredding your cardboard.
Peel off all laminates
Any plastic film on the cardboard can greatly slow down the breakdown process. Peel it off to also avoid choking some young roots in that compost, should you miss it when planting.
Flatten the cardboard
If the cardboard is in some other form, dismantle it and flatten it. This way, your box cuter will excel at it does best.
Soak the cardboard in water
To further simplify your job, wet the cardboard with water before cutting.
If you cut along the corrugated lines, it’ll feel more of tearing than shredding, and it will make the deed effortless.
Inspect for metallic staples
Right after wetting cardboard boxes or stapled books, check the whole heap for metal staples. Although some people argue that the pins eventually corrode away into the soil mix, it takes time. It’s not rare to find stainless steel staples, which could take years to even look corroded. Remove the staples to avoid an unwanted eventuality.
Leave a few larger cardboard pieces
Compost needs to be humid throughout.
To avoid drying out the compost, you can reduce the rate of evaporation. Place a few wider pieces of cardboard to cover the compost box.
Moisture will be locked in, and the breakdown process won’t take long.
How to shred cardboard for compost
Sometimes shredding cardboard can become a nuisance, especially if you have lots of it stored up. There are several ways in which you can shred cardboard more effectively.
Let’s look at 4 ways you can do that.
- Using a shredder
Some shredders (link to Amazon) are specifically designed to shred cardboard.
They’re heavy-duty, so they can’t be compared to regular shredders. These heavy-duty shredders can comfortably cut through three hard layers of cardboard with ease, all in one go. That, however, doesn’t mean that a regular paper shredders (link to Amazon) can’t get the job done, particularly if you only have a little cardboard stored.
Ensuring that the shredder’s blades are sharp enough to cut through the boards is the only secret for efficient running. One downside of the regular paper shredders is that their blades tend to dull quicker than their heavy-duty counterparts. A dull shredder will jam the cardboard as it passes through. To prevent jamming, applying oil on your blades is occasionally recommended so that the shredder runs efficiently.
- Making the cardboard wet and using your hands
This method is pretty straightforward. If your shredder can’t handle sturdier pieces of cardboard, then this method might be the fix.
All you have to do is lay your cardboard boxes on a flat surface, pour some water onto them, and then start ripping them apart. Wet cardboard is always easier to cut.
Lay the wet cardboard on a damage-proof surface and cut the board into thin strips using a utility knife. You can determine the strip size you want for your compost. Thinner stripes may take up a lot of time, but they decompose faster than thicker ones.
To facilitate slicing the cardboard, cut along the cardboard corrugations to save time and energy.
- Using a box cutter
A box cutter (link to Amazon) has sharp blades that can cut through your cardboard easily, hence why you should be careful when working with it.
Ensure that you have lots of space and a platform where you can set the cardboard at a comfortable height for ease and safety.
Grab your box cutter and hold it at a 45-degree angle, then cut the cardboard by dragging the cutter towards your direction. Be at a safe distance such that if the blade snaps, no accidents will occur. To prevent accidents, you can shorten the blades, so you apply pressure evenly and reduce any chances of the blade snapping.
If you are working with corrugated cardboard, ensure that you exert enough pressure, so you cut through it effortlessly. You can also place a non-slip mat on the working surface to protect it from scratches and cuts.
- Using a chipper
You can choose to shred the cardboard in a garden chipper or wood chipper (link to Amazon), as they can both get the work done. The only thing you have to do is feed your cardboard into the chipper and voilá.
It might be a little difficult to get thin cardboard strips using a chipper, but you can solve that by soaking the cardboard in water and leaving it outside to dry for a few days, as that will take care of the hardness that leads the cardboard to crumble.
Do not forget to change the wood chipper settings before you feed it with the cardboard!
Should you really use cardboard for compost?
Using cardboard boxes is a pretty rewarding method to create compost.
They are rich in carbon, which, when shredded, quickly decompose to improve your compost pile.
Cardboard is also a good insulator and works best on compost bins that have side openings. That way, there is heat to speed up decomposition even during colder seasons.
Using cardboard is also excellent for dealing with the wet and foul smell that sometimes emanates from compost when it has excess nitrogen.
So, yes, you should absolutely use cardboard if you have some available!
High fiber composting
Composting is not always done in a rural environment.
You can also do it in an urban setup, usually to take care of kitchen waste.
If you’re in the city, there’s a method called high fiber composting, which addresses the low supply of dried leaves.
Typically, food waste has to be combined with plant foliage, or else you end up with compost that smells and takes longer to decompose.
High fiber composting is simply a method that consists of adding all cardboard (including packaging, toilet roll tubes, cereal boxes)to kitchen compost. The fibrous material in cardboard is rich in fiber, so it balances out the nitrogen from the kitchen waste.
Just make sure that you distribute the cardboard evenly throughout the kitchen waste, and stir it well to increase the surface area and improve aeration in the compost.
Cardboard boxes are a great source of carbon.
Fortunately, you can find them everywhere as most companies use cardboard boxes when shipping products. Once you find a stack of them, flatten them up and cut them into small pieces for a more quick decomposition.
If you don’t have a lot of time, or you feel like it might be too exhausting to use your hands to shred cardboard, consider using a tool like a paper shredder or a box cutter.
If you wish to learn all the details on how to shred cardboard, be sure to read the article.