What Does Compostable Mean? It's Not As Simple As You Think

Right now, the boom of “compostable materials” is opening the door for everything from phone cases to cutlery  to earn the title of a compostable product. But that doesn’t necessarily mean you can just toss these items in your backyard compost pile. So, if not that, then what does “compostable” mean?

For many of us, the word “compostable” conjures up images of a fresh pile of dark, nutrient-rich soil, made up of food scraps and yard debris or plants. You may think of a compostable material as something that you can toss in your backyard garden and find entirely decomposed a few months later. But with the rise of bioplastics and other engineered, but compostable, materials, the meaning of the word has gotten a bit more complicated.

So, what does compostable mean?

A compostable product or material is something that will turn into soil or fertilizer through the process of decomposition. This means that given the right environment, the material will effectively disintegrate into that dark, nutrient-rich soil in a relatively short amount of time. A general rule of thumb is that compostable items will turn into soil in the same amount of time that it would take to decompose natural matter like leaves or dead plants.

The Big Difference: Backyard Compostable vs Commercial Compostability

Regardless of if it’s done in your backyard compost pile or at a commercial facility, the process of composting is quite similar. The difference between backyard composting and commercial composting is that the latter has more control over the environment that materials are composted in. A big factor in successfully composting more difficult items, like compostable plastics, is how much heat is needed to break them down. While backyard compost piles naturally produce some heat in their process, it’s not enough to help some items decompose. At a commercial compost facility, factors like heat and moisture are carefully controlled to ensure that items decompose in an ideal environment. Some items, like food scraps, can be composted in your backyard or a commercial facility. Others, like bioplastics, will only break down in a commercial compost facility. While many cities have composting programs that make it easy to properly dispose of any compostable item, others don’t. So if you live in an area without commercial composting, look closely at your items to ensure you’ll be able to compost them on your own.

Now here comes the tricky part: what happens if you place something that’s commercially compostable in your backyard compost? Or, if something that’s compostable doesn’t make it to a compost bin at all? Simply tossed in your backyard garden, compostable items will eventually decompose, yes. But, without the proper mix of soil, air, moisture, and other factors, they will decompose anaerobically. This process leads to the release of methane, which contributes to climate change. On the other hand, if given the right mixture of factors, compostable items will break down aerobically, and release a much smaller amount of methane. The exact environment needed to compost certain items can vary, which is where confusion around the compostability of products comes into play.

Can Compostable items be recycled?

If you don’t have access to commercial composting, you might hope for the next best thing. However, compostable does not equal recyclable. In fact, compostable items can actually damage recycling equipment. So it’s important to dispose of compostable plates properly. Unfortunately, this means that if your compostable item needs to be processed in a commercial composting facility but you don’t have one in your area, you’ll have to toss it in the trash. Items like compostable plastics require these facilities so, depending on where you live, options that are backyard compost certified are a better choice.

Compostable vs Biodegradable

No discussion about compostability is complete without understanding a little bit about biodegradability. Sometimes, the words compostable and biodegradable are used interchangeably. But there’s an important difference between the two. And it will help you understand the real impact of the products and materials you buy as well as how to dispose of them.

Compostable items are those that break down fully into organic (i.e. non-toxic) matter in a specified amount of time. Compost soil and hummus can safely be used in gardens and farms to provide important nutrients to new growth. Typically, items that state they are compostable need to go through testing to prove they will break down in a relatively short period of time. Organizations like the Composter Manufacturing Alliance (CMA)  work with producers to test products for proven compostability. And, they also help people properly dispose of compostable items.

Biodegradable items have a much broader definition. Something that is loosely termed “biodegradable” will eventually decompose, no matter the conditions, but there is no guarantee that it will result in safe, organic matter. For example, plastic is technically biodegradable. It will take hundreds of years, but eventually plastic breaks down into microscopic bits. However, the tiny microplastic particles it leaves behind are hardly safe for the environment. While most of us would consider plastic as non-biodegradable because of this, the rules around what can and cannot be called “biodegradable” are loose. In recent years, the rise of greenwashing has led companies to claim that their products are biodegradable. But with no distinction of how long the process takes, or what is left behind, these claims are often misleading.

So, how are compostable and biodegradable items related? Anything that is compostable (like a bamboo plate) is also biodegradable. But, not everything that is biodegradable (like plastic) is compostable.

When it comes to disposing of items, compostable vs biodegradable can be an area of confusion. So keep this in mind: if an item only states that it is biodegradable, you’ll have to toss it in the trash. If it’s certified compostable and biodegradable, you can safely send it to compost.

4 Tips To Help You Properly Compost Anything from Bioplastics to Compostable Plates

While it seems straightforward, the world of composting can be tricky (as you now know). While these guidelines are great places to start, consider referring to standard-setting leaders such as the CMA if you’re not 100% sure how and where something should be composted. And check out this handy map to find composting facilities near you (and get updated information about what each facility accepts).

Because no certifications are required to mark an item as biodegradable, you simply don’t know how long it will take for these items to decompose. And, because they’re not compostable, you’ll have to throw those vaguely marked items into the trash bin, not the compost.

Speaking of certifications, look out for them on any item that claims to be compostable. Companies that certify their products as compostable have taken them through a process that guarantees that they are compostable. Just check to see whether the certification is for backyard compostability, or if the item is only commercially compostable.

Some items, like compostable plastics, aren’t accepted at every composting facility. If you’re not sure about an item, reach out to your local composting branch for more information. Sometimes they’ll send you an easy-to-use guide that you can use to quickly sort items.

If you live in an area with access to commercial composting facilities, or the items that you use on a regular basis aren’t accepted at your local program, consider an electric composter. Some, like this one, have gone through rigorous testing to ensure that they can safely decompose any item, including those that are only certified as commercially compostable.

As you can see, the question, “what does compostable mean” is a bit more complicated than it seems. But composting is worth the work! By supporting the use of natural materials and properly disposing of them, you are helping to reduce methane emissions and keep items out of the landfill.

Ready to swap plastic for plants? Try Compost Manufacturing Alliance Certified dinnerware made from organic, biobased bamboo.