Cardboard in Compost – How Long Does It Take To Decompose?

Last Updated on January 12, 2022 by Grow with Bovees

When it comes to composting, we’re all familiar with common composting materials to put in a compost pile like food waste/ingredients, other organic matter from your kitchen and garden, but there’s often confusion on whether cardboard material can be composted.

The quick answer is yes.

You can add layers of cardboard to your compost heap or tumbler for a smooth composting process.

According to the United States Environmental Protection Agency, cardboard waste makes up over 23% of landfills in the country, which greatly increases its carbon footprint, and releases toxic chemicals into the environment.

What Types of Cardboard Can I Compost?

The composting methods for cardboard aren’t difficult, as long as you use the right type of cardboard and setup and maintain your compost heap correctly on a flat surface or larger surface depending on its size.

You can add just about any cardboard to compost heaps including large boxes and individual sheets.

When it comes to compost cardboard, here are three different types of cardboard to compost namely corrugated cardboard, flat cardboard, and wax-coated cardboard, but be sure to remove any tape, staples, and glue prior to the process.

Corrugated Cardboard

People generally use the word cardboard when referring to any type of paper-based material. However, there’s a big difference between the different types of cardboard.

This type of cardboard is made up of paper pulp, and is typically used in packaging, so that Amazon box you received today is most likely made from corrugated cardboard.

You can use any type of corrugated cardboard as compostable material in your compost heap, as long as it’s broken down into small pieces.

Flat Cardboard

Flat cardboard, just as the name suggests, is the flat-surfaced cardboard that you usually find in cereal boxes, shoe boxes, pasta boxes, and thin flat cardboard boxes and is an ideal material to add to your compost bin.

Wax-coated Cardboard

Wax-coated cardboard is a relatively biodegradable material that’s a little difficult to compost. This type of cardboard compost material is found in wax-coated paper cups, plain cardboard boxes, pet food bags, and food paperboard boxes that are used for food packaging.

For example, corrugated cardboard breaks down quickly, whereas wax-coated cardboard can take a significant amount of time.

In terms of composting cardboard, most types of cardboard are biodegradable, but the time it takes for the microorganisms and other decomposers to break the fibers down in the decomposition process depends on the type of cardboard.

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Wax-coated cardboard features a wax coating, which prolongs the decomposition process. Therefore, it can take up to five years for the wax-coated cardboard composting process to complete.

However, regardless of the type of compost cardboard, there are certain things you can do to accelerate the entire decomposition process such as shredding the pieces of cardboard and mixing the pieces with appropriate soil. Adding to this, soaking the cardboard pieces in water helps speed up the composting process.

Is a Cardboard Compost Pile Good for Soil and Plant Life?

Cardboard is a source of carbon and is made from all-natural materials, hence breaks down in natural elements, leaving no harmful toxins in the soil and garden beds.

Carboard comes from trees, and kills pesky weeds, and encourages the growth of earthworms. Apart from cardboard compost, you can also lay down some carbon in your garden path to kill lawn grass, and cover it with pavers. The cardboard will then decompose into the soil over time, and kill any unfavorable plants and insects. [a]

How to Shred Cardboard and Use Cardboard for Compost?

It’s highly important to use shredded cardboard boxes and other types of cardboard before adding them to your compost heap because larger pieces will not decompose as quickly.

There are a few things to do before shredding cardboard for composting like removing any plastic tape, extra tape, glue, and flattening the cardboard before shredding it.

Shredding cardboard can be a very daunting and time-consuming process but you can use any one of the below-mentioned methods to ease the task.

The Classic Shredding Method

The first most important thing to do is steer clear from using scissors for the classic shredding method but invest in a good box cutter.

Get a good grip on your box cutter, and slice the cardboard along the lines of the corrugation, and not against them.

Continue cutting the cardboard until you shred it down into more manageable strips such as small 5-inch to 8-inch strips.

You can now do one of two things-use your hand or the box cutter to break the cardboard down into smaller 1-inch strips or feed the cardboard through an electric shredder.

If you have a lot of cardboard to shred or shred cardboard often, buying an electronic shredder is a great option.

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The Amazon Basics paper and cardboard shredder is one of the best budget-friendly models you can get in this segment and shreds up to an impressive 24 sheets of 20-pound bond paper at one time.

It can also be used to shred slightly tougher materials such as cardboard, CDs, DVDs, and credit cards.

When you shred cardboard with an electric cardboard shredder, the results are light and airy cardboard pieces that are great for vermicomposting.

Shredding Cardboard without a Shredder – The Wet Cardboard Shredding Technique

If you soak paper in water, it becomes easier to tear it into smaller pieces. Similarly, soaking the cardboard in water makes it easier to shred it into smaller pieces. If you live in an area that receives a good amount of rain, you can just leave the cardboard out to make it easier to break up.

Alternatively, you can soak the cardboard in a large tub of water for roughly two weeks. Remember, the cardboard will absorb some of the water, so be sure to keep topping up the water in the tub, after which you can use your hands or a drill with a paint mixing attachment to shred the cardboard.

Lasagna Method

Have you heard of lasagna gardening? Also referred to as sheet composting, lasagna gardening is an age-old technique that has nothing to do with growing anything in the garden but entails adding layers of organic materials that will turn into decomposed material over time.

This slow compost process requires little or no effort, so get started by laying down sheets of cardboard, which then get converted into useable compost in the soil below.

You can even add layers of cardboard over your compost heap that contains spoiled food, food crumbs, and other nitrogen-rich (green) ingredients to speed up the black gold (compost) making process.

It takes a few months for the fungus to break down the cardboard lasagna layers, so it’s not a quick process compared to composting kitchen scraps.

Quick and Easy Chipper/Shredder Method

If you don’t want to deal with prepping the cardboard before shredding into smaller pieces or if you have a truckload of cardboard to shred, using a chipper to get the job done is highly recommended.

For this method, you will need a wood chipper like the GreatCircleUSA Wood Chipper. This 3-in-1 wood chipper/shredder/mulcher is powered by a robust 7HP 4-stroke gas powered engine, and can be attached easily to your lawn mower, ATV or small tractor.

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The wood chipper cardboard processing method is eaay, where you first remove all the plastic tape from the cardboard, roll up the cardboard, and feed the roll through the hopper of the wood chipper.

High Fiber Composting

High fiber composting is a type of composting system that consists of adding all types of cardboard, toilet paper rolls, paper towel rolls, packaging, cereal boxes, etc. to kitchen waste.

This mixture is rich in carbon (cardboard), and high in nitrogen-rich materials (kitchen waste), hence provides a well-balanced compost system.

This material should be distributed evenly throughout your compost heap, and mixed well to improve aeration in the pile. If your compost pile contains a large amount of nitogeneuos material such as kitchen vegetable waste, grass clippings, etc., adding high-fiber compost is a great idea.

Is Composting Cardboard Better than Recycling?

When it comes to getting rid of several things that have outlived their purpose like kid’s plastic toys and cardboard packaging, we now have several options-reuse, a recycling bin, repurpose, and compost.

You can literally compost anything and avoid the landfill altogether, starting from orange peels, to bones, to bottles and much more.

Cardboard and paper products make up a sizable chunk of total waste, so both recycling and composting are two great methods to avoid contributing to that huge quantity of landfill waste.

When you recycle cardboard or paper, it basically gets reintroduced into the system, so you eliminate the need to cut down more trees to produce more cardboard and paper.

But recycling cardboard isn’t all sunshine and rainbows, because this process produces an inky sludge that contains metals such as zinc, chromium and lead that can seep into water supplies.

By composting your cardboard instead of recycling it, you don’t have to worry about recycling bins, transporting the cardboard to the recycling plant or the harmful chemical processes used to manufacture fresh cardboard.

Rather than recycling cardboard, you can allow it to decompose into the soil to make your tomatoes and other veggies grow.

Take note that a good compost pile requires a balance of both green and brown waste. You get the nitrogen-rich green waste from things such as vegetable trimmings and fruit peels, and brown waste from paper products such as cardboard.