Common Misconceptions About Home Composting: What Can and Cannot Be Composted

LiviosThere are many misconceptions about what you can and cannot compost at home. So it’s high time to get rid of some of them, because from the beginning of 2024 we prefer not to throw food surpluses into the residual waste. Bouwsite Livios therefore consulted Vlaco, the organization that is responsible for the quality monitoring of composting installations in Flanders and correct communication regarding home composting.

Coffee pods and tea bags

“You can certainly add coffee grounds to the compost, but it is better not to compost coffee pods and tea bags,” explains Kristof Van Stichelen, specialist at Vlaco. “After all, such a coffee pod or tea bag often seems to be made of paper, while in reality it often consists of synthetic material. And that doesn’t digest. Or it breaks down into microplastics that pollute your compost and your soil.”

So don’t compost at home. “Or you just throw the contents of the coffee pod or tea bag into the compost. The casing goes with the residual waste anyway.”

Once you have quality compost: how do you use it correctly in your garden? And how much exactly?

Eggshells and shells

“Nature itself can break down calcareous materials such as eggshells and shells, but this process is very slow. Moreover, you are not legally allowed to compost kitchen waste that may contain animal (by)products. Why not? Because such kitchen waste can attract wild animals, which then eat it and – possibly – spread animal diseases.”

So don’t compost at home. “Eggshells are allowed in the organic waste collection. You simply throw shells from mussels, for example, in the residual waste.”

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Citrus peels

“You sometimes hear that citrus fruits are too acidic to compost. But don’t worry: microorganisms simply break down those acids and convert them. It will not make your compost(more) acidic. You certainly shouldn’t add lime to it either.” Orange peels do not compost, they just become moldy, you also often hear. “But fungi are important for decomposition.”

Composting at home, that is. “Of course. For smooth digestion, you can possibly reduce the peels a bit and mix them well with all other composting material.”

Tip: Through this job you will learn to make a compost bin with mesh.

Potato peels

This would not be good because potatoes would have been treated to prevent premature bolting and sprouting. “That was indeed done in the past, but nowadays (almost) not anymore. To be sure, rinse the potatoes before peeling them. Sometimes potatoes are ‘gassed’ to prevent them from germinating, but that process has no effect on composting.”

Are the peels not digesting? “The starch digests very quickly, but the peel itself may be a little slower. Potato peels can then form shoots, instead of completely decomposing. This usually happens on the outside of your compost bin or bin, where the composting mass dries out. In that case, regularly stir and aerate the decomposing material. This way, composting gets started again.”

Composting at home, that is. “But do follow the above tips. And mix sufficiently with other organic material. Composting a lot of ‘the same’ – for example only potato peels – is never good.”

What about sick foliage on potatoes, tomatoes…

“Are (parts of) plants affected by nematodes, insects or mites? Then you can compost those plant remains at home without any problem. Those creatures will die during composting.”

“Are your remains affected by fungi, bacteria and viruses? For example, is it tomato foliage with mildew or potato foliage with ‘the plague’? Then we expressly advise against composting them at home. The risk is too great that it will not get warm enough in your own compost heap and that harmful micro-organisms will remain alive.”

So it’s better not to compost at home. “Certainly not if the foliage is clearly affected by fungi, bacteria or viruses. It is better to give these diseased plant parts to the organic waste collection or take them to the green container of your recycling park.”

And what about lava flour, basalt flour and bentonite?

“I can be very brief about that. There is no scientific evidence whatsoever that this would promote composting.” So don’t spend any money on it.

Getting started around your home? Be inspired and informed thanks to our free magazine ‘My Garden and Terrace’.

Knowing more? You will find an extensive composting brochure on the Vlaco website. And check the compostability of garden and kitchen scraps via the Home Composting Guide.