How To Use Cardboard In Compost: Do’s And Don’ts

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Humans are incredibly creative animals, but we’re also very wasteful. In recent history, however, a growing number of people have begun to realize the value of trying to cohabitate more peacefully with nature by going “off the grid.”

However, knowledge of how to achieve this is mostly relegated to often hard-to-find periodicals such as Mother Earth News Almanac (A periodical very similar to the Old Farmer’s Almanac but focusing on green living).

Cardboard in CompostPin

The good news is that you can begin to live a much greener life with far less effort than you think, especially if you love plants.

A prime example of this is composting, and all of those Amazon packages can actually be used to make a wonderful organic compost that will help your garden thrive.

Here’s all you need to know about composting cardboard, including what things you should avoid doing.

How To Use Cardboard In Compost: Dos and Don’ts

Cardboard is one of the most reusable eco-friendly materials we produce and one of the most wasted, making up many of the trash landfills.

However, not all cardboard is created equally, and there’s a bit of a trick to effectively composting it.

Does Cardboard Make Good Compost?

Cardboard, at its core, is little more than processed wood pulp and glue.

The glue is generally biodegradable and often made of organic components since it doesn’t have to be very strong.

This means that most cardboard makes for a great addition to a compost heap.

For example, cardboard encourages aeration, speeding up the composting process and allowing the release of nitrogen and other nutrients to occur more evenly.

When cardboard-enriched compost is used with plants, the green material can help roots expand while creating a gentle barrier that keeps the roots from getting tangled with one another.

Another great benefit of this carbon-rich material is absorbing water and slowly releasing it.

This has the benefit of ensuring your compost is never too moist or dry.

Types Of Cardboard Safe For Composting

When using cardboard, you must be careful about which types you add to your compost.

There are essentially three safe types out there:

Corrugated Cardboard

Corrugated cardboard is the way to go when you want the fastest, most efficient composting possible.

The same air pockets that give this cardboard strength also encourage superior airflow and speed up composting.

This is the most common form of cardboard used in packaging and protective filler, so it’s easy to get hold of.

You can use this form of cardboard for all three major composting methods.

Flat Cardboard

The non-corrugated variety is still around and remains a common option, even with packaging material.

This type is a little less efficient than corrugated due to its denser construction and is usually best when shredded, although it can also be used for the lasagne method.

Wax-Coated Cardboard

Okay, this one’s somewhat debatable.

Wax-coated cardboard is usually flat, with a thin layer of wax added to make it more water-resistant.

In some cases, it’s perfectly safe to compost this material, although it will take a lot longer and require some preparation.

To make this cardboard safe for composting, you’ll need to completely submerge it and let it soak until the wax dissolves, resulting in “green” flat cardboard.

Types of Cardboard Not Safe for Composting

Since we mentioned wax-coated cardboard is debatably safe, let’s start with the instances where this type of cardboard ISN’T safe for composting.

Some cardboard has been so saturated with wax that it’s impossible to soak it all out.

Using this cardboard in composting will just gum things up, although it actually recycles quite nicely.

Also, wax-coated cardboard often has a lot of dyes or inks and other chemical additives that contaminate it.

A good example is a printed drink container from a fast-food restaurant, which is first printed, then coated heavily in wax.

The mess printing you have on your cardboard, the better.

Another key factor is that you want the cardboard to be “green,” meaning no heavy dyes or other obvious contaminants.

Remove any shipping labels or tape from the cardboard before adding it to your compost, as these materials may not degrade and can negatively impact your compost.

Examples Of Safe Cardboard

  • Dull finish (basic wax coating that can be safely removed)
  • Little or no printing
  • Paper towels or toilet paper rolls
  • Uncoated food containers (pizza boxes, cardboard egg cartons, etc.)*

*The greases and oils left over from prepared food can make these boxes difficult to recycle but are actually beneficial to the composting process.

Examples Of Unsafe Cardboard

  • Heavily dyed (such as soda cases or posterboard cereal boxes)
  • Shiny boxes (the wax contains plastic)
  • Still containing tape or shipping labels

The Three Methods of Composting Cardboard

Now that we’ve covered cardboard types’ dos and don’ts let’s look at the actual methods.

There are three basic methods to choose from:

  • Lasagna Method: This is great if you don’t mind the extra wait and have the space, as it can take 8 to 12 months for the cardboard to break down fully.
  • Layering Method: Similar to the lasagne method, layering uses smaller pieces and takes around 6 to 8 months to decompose.
  • Shredded Method: This is the fastest method overall, taking around 2 to 3 months to decompose, but there’s far more prep involved.

DO NOT try just to chuck your cardboard into the compost pile, as this can severely slow the process and may even prevent proper composting.

How To Compost Using the Lasagna Method?

This is truly a “set it and forget it:” method.

Begin by cutting your cardboard down enough to lay flat in your composting container.

Lay a single layer of cardboard on the bottom, then spread a layer of soil on top.

Dampen this layer, then repeat the process until your compost bin is full, adding one last layer of cardboard on the top.

This method takes a lot longer, but you won’t need to turn the compost, as the layers effectively ensure that the process occurs evenly throughout.

As a bonus, you can actually do this method INSIDE a cardboard box, provided that box also meets the requirements for composting.

How To Compost Using the Layer Method?

This method is truly the middle ground and will require you to shred the cardboard partially.

As with the lasagne method, you’ll want to add the cardboard to your composting soil in layers, although you don’t need to be as precise.

Because the cardboard is in smaller chunks, it will degrade faster, although not as fast as shredded cardboard.

Note that you will need to turn this compost occasionally.

On top of the cardboard, you can also add nitrogen-rich materials, such as spoiled vegetables, grass clippings, fruit peels, kitchen waste, and horse or cow manure.

How to Compost Using the Shredded Method

While shredding results in the fastest decomposition, it also requires the most work.

Shredding the cardboard speeds up the decomposition process.

Begin by finely shredding sheets of cardboard until the pieces are around 1” inch wide.

Thin cardboard can go through a paper shredder, but you’ll have to do anything thicker by hand.

Mix the shredded cardboard into your compost pile and turn the pile every few days to ensure even composting.

You can also add high-carbon materials, such as dead leaves, old hay, or straw, to your shredded cardboard.

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