Can You Compost Cork? (Here’s What You Need To Know)

If you’ve got cork from anything – such as perhaps a wine bottle or a champagne bottle – you might be wondering whether you can put the cork in your compost bin.

Will it break down and disappear? Could it potentially harm your compost?

In short, yes, cork can decompose because it is a natural material, and no, it won’t harm your compost.

However, there are still some things you should look out for, which I’ll cover below.

What Is Cork And Can You Compost It?

Cork is an amazing, natural substance that is made from the bark of a specific kind of tree. It is light, impermeable, and non-flammable, and its biggest commercial use – so the place that you’re most likely to get it from – is as a wine stopper.

And yes, you can compost cork! It is a natural material and it will break down in the compost like most other organic things. Being made from trees, it’s a woody substance, and it counts as a “brown” in your compost bin, meaning it’s carbon-rich. 

How Long Does It Take?

Composting cork does take a while. It’s impermeable, which is partly why it’s such a useful material, but that also means it won’t break down fast. With no liquid able to pass through it, it won’t “rot” in the same way that most food will, so you may notice it hanging around your compost bin for longer than you expect.

Don’t panic – it will disappear eventually, but there are also a few things you can do to speed it along a bit.

Firstly, chop it up into small pieces. Some people even recommend grinding cork before adding it to the compost. While that might seem excessive, you should break it up a bit with a knife before you compost it. Cut your wine corks into quarters or smaller to make sure they’ll break down quickly. 

Remember too that cork is a brown ingredient, and you will need to add plenty of green material to help it break down. Greens are things like grass clippings and kitchen waste, and without them, your compost won’t break down fast, if at all!

Adding plenty of grass clippings will also encourage your compost to heat up, and this will further speed up the process. Just make sure you don’t add too many, or the heat will kill off the bacteria you need to keep the compost functioning, and it may end up slimy and too wet.

Finally, stir the heap regularly if you add a lot of cork – it may take a while to break down otherwise. This will ensure the cork is constantly being mixed with other ingredients and doesn’t end up in an impenetrable clump that the worms and bacteria can’t handle.

What To Watch Out For

Although cork itself will break down perfectly well in a compost heap, there are a few caveats to check before you drop a pile of corks into your compost heap.

Fake Cork

Not all wine corks are real cork, sadly. Synthetic corks are becoming more and more common, and these are not something that you want to drop into your compost heap! If you’ve handled both kinds of “cork,” you may be able to tell easily which is which, but if in doubt, try cutting them in half.

If the inside of the cork looks very neat and tidy, with an even, “foamy” texture, it’s likely a synthetic cork. A real cork will look a little less even and a bit more “woody” inside.

You may also notice that synthetic cork is paler, or feels waxier – this won’t always be the case, but it often is. If in doubt, hold the cork near (but not in) a lit match. Synthetic cork should melt, and real cork will burn and singe.

Don’t let it catch fire, but just see how the material responds and then put the match out. It’s best to do this over the sink, just in case, as real cork burns well (being basically very dry wood!).

Things Attached To The Cork

Make sure there’s nothing attached to the cork if you’re going to compost it. For example, look out for plastic tags, foil lids, material to help it screw in place, etc. If you can’t pull another material off, try cutting the cork with a sharp knife to remove it, but be careful not to cut yourself.

Don’t compost any of the things that might come with cork; take them off and either put them in your general waste or, if appropriate, in the recycling bin.

Treated Cork

Cork that has been coated for some special purpose should not be composted. If you know that cork has had glue, sealant, chemical sprays, or anything else on to make it suitable for its original purpose, don’t put it in your compost bin.

This is unlikely to be the case for any wine corks, so you shouldn’t need to worry about those. With other cork, think about the original purpose and consider whether it’s likely to be treated.

What About Other Kinds Of Cork?

You might be wondering about cork floor tiles (cork floors are lovely!) or cork noticeboards, etc. Can you compost those when they reach the end of their lives?

The answer is that sadly, you probably can’t. They will likely have been in contact with glue or sealants (possibly both), and therefore will contaminate your compost with either chemicals or plastics. Cork that has been sealed will also struggle to break down.

These will need to be disposed of in the general waste bin. If only a bit of the cork (for example, perhaps the corners of the noticeboard) have had glue or paint on it, you may be able to break that part off and compost the rest.

What Else Can You Do With Cork?

Cork has other uses if you don’t want to compost it. There are some special recycling programs that will turn cork back into other products, reducing the strain on cork harvested from new sources. While the harvesting of cork can be done sustainably, reuse is still a good idea.

Check out local eco-friendly shops or wine suppliers and ask them about recycling options. You may even be able to find addresses that you can mail corks to.

Alternatively, you might find cork uses in your home. It is easy to make a cork noticeboard out of old wine corks, and you can also turn them into coasters, bath mats, key chains, and many other things. If you do decide to reuse cork, try to minimize glue/paint so it can be composted when you’ve finished.

As an alternative option, you can use cork in your fire. As mentioned, cork burns very well, and if you wrap it in a sheet of newspaper and light the newspaper, it will burn for a long time. It’s a great fire-lighter and perfect for taking on camping trips.

However, if none of that sounds appealing, it’s good to know you can just toss it in your compost bin, and it will return to nature as well as other organic materials!

Conclusion

If you’ve got cork hanging around that you want to get rid of, composting it is a great option. It will add nutrients to your compost, and also provides a bit of structure, as well as increasing carbon to help keep it balanced.

If you add a lot of cork, consider breaking it into small pieces so it doesn’t clog up your compost or take too long to decompose.