Composting is good for the planet, good for your garden, and good for your kitchen, but that doesn’t mean it always goes smoothly.
No matter how simple composting may seem on the surface, it can (and often does) go wrong, particularly if you add things that shouldn’t be in the compost bin.
With that in mind, here are 21 things you should NOT put in a compost heap from the kitchen.
Some of the top things you should avoid putting in your compost heap include: meat, fish, and dairy, along with teabags, certain paper products, inorganic waste, dryer lint, pet waste, and plenty of other everyday items.
A teabag might seem a very innocuous thing to add to your compost heap, and the tea itself is, but unfortunately, the bag is something you should steer clear of adding to any organic waste pile.
That’s because many teabags have a fine plastic mesh that is designed to prevent the tea leaves from going everywhere in your cup.
The mesh won’t break down properly, because it’s plastic, but it will shed microplastics into your compost heap.
Worms and bacteria won’t benefit from the addition of teabags, so avoid adding them unless you are able to source ones that are specifically plastic-free.
Some brands have started to provide these, but make sure before you buy them.
You should also watch out for coffee bags if you use them, as these can cause the same issue.
If you prefer, you can cut the bag open and tip the tea leaves into the compost, and then put the outer bag in the general waste.
This might seem like a very broad category, but you should avoid composting meat.
While meat is an organic substance that will break down over time, like other compostable materials, it is not something you should be adding to a home composter.
Meat is very attractive to animals, and it also has a strong smell that will advertise its presence to scavengers.
If you add meat to your compost, you may attract rats, opossums, badgers, etc. They may linger even after the meat has gone, living on other parts of the compost.
Meat also smells awful as it decays, which could be problematic if you have a small garden or your compost is close to a boundary with a neighbor.
It is best to avoid including meat in compost bins.
Three: Oily Foods
A little bit of oil is not going to cause problems in an established, large compost heap, but a lot of oil could upset the balance.
Oil doesn’t break down easily, and because it will coat things in the bin, it may slow the overall decomposition process.
Remember, your compost depends on water in order to break down properly, and adding a lot of oil to the mix prevents it from composting.
While small quantities of oil should just run off and disappear into the soil, any large amount of oil will cause issues.
This goes for all kinds of oil, including butter and animal fats.
Four: Citrus Peels
Orange peel might not seem like a bad thing to add to your compost bin, but it can cause big problems.
Firstly, it takes a long time to break down because it is fibrous and tough. Secondly, the worms – which are a big contributor to the composting process – do not like citrus much.
Citrus fruits have a strong smell that deters worms, so if you have a lot of lemon skins or orange peels, don’t add them to your compost.
If you do need to add them, try cutting them up small to reduce the concentration in one spot and encourage them to break down quickly.
Five: Baked Goods
Bread and other baked goods are another apparently harmless food that you should think twice before adding to your compost heap.
It’s not a problem to add a little bit, but significant quantities may cause issues.
Again, baked goods attract unwanted attention from pest species, and bread molds very fast, which can result in a moldy, smelly compost pile.
If this occurs, turning the compost to disrupt the mold should be sufficient to deal with it, but be careful not to breathe any spores in.
It is better to avoid adding the bread in the first place if possible.
Six: Dairy Products
Dairy is also an attractive food to many pest species, and can add unwanted oiliness to your compost bin (depending on the kind of dairy you include).
In small quantities, it is unlikely to cause a problem, but a large amount of dairy is not good for your compost.
It may, like meat, attract flies as well as bigger pests, and this can be unpleasant if your compost is in a part of your garden that you use a lot, or near to the house.
If you do need to add dairy to the compost, try to bury it in the center of the heap to disguise its scent and keep it away from flies.
That said, dairy (particularly milk) is good for the compost because it contains a lot of nutrients.
If you are able to deal with the above problems by burying the dairy and only adding it in small quantities, you may find your compost actually benefits.
Like citrus peels, onions and onion skins can prove unpopular with the worms. This could lead to the onions hanging around in the compost bin for longer periods of time.
If you add a lot of onion to your compost, you may discourage worms that deal with other food scraps, so it is not a good idea to do this.
Although onion peels don’t have a strong scent, they are fibrous and will take a long time to decompose.
As well as being attractive to pest species, fish stinks once it has gone off, and this is an issue in a backyard compost bin.
Even if it doesn’t bother you, it may upset your neighbors.
Moldy fish will act as a magnet to scavengers, and should be avoided or buried at the very bottom of your compost heap to try and minimize the smell it produces.
Nine: Sticky Labels
You might be wondering why you would have sticky labels in the kitchen, but think about produce, particularly fresh fruit.
This often has a sticky label applied so that single pieces can be scanned at the checkout.
This sticky label is very easy to forget about and if you compost a shriveled apple or pear, you may not even think about the label, but it won’t break down in the compost heap.
The labels contain plastic or vinyl, and are not biodegradable.
If added to a home compost heap (or even a commercial composting facility), they will simply get dirty and refuse to break down.
Do not put them in your compost heap.
You may find that it’s best to remove these stickers as soon as you get your produce home to reduce the chances of them finding their way into the heap.
Ten: Cooked Rice
Cooked rice, as you may know, can grow some very nasty mold, and adding it to your compost heap is not necessarily a good idea.
While any fungus growing on the rice will disappear once the rice has been consumed, having it there in the first place puts you at risk of breathing in mold spores, especially if you turn your compost regularly.
If you do end up with mold on your compost, cover your face before handling it to reduce the chance of inhaling the spores.
Eleven: Waxed Cardboard
Cardboard is generally good for your compost, but waxed or coated card is not. You may find quite a few coated cardboard products in your kitchen.
Anything cardboard that is designed to hold liquid is likely to cause problems unless it specifically says it is compostable.
That means cardboard coffee cups are not compostable.
Coated, shiny card is also a bad idea on the whole, as is heavily dyed cardboard.
Cereal boxes, for example, may not be great for your compost bin because of the dyes they could contain.
It is best to recycle these if possible, rather than risk adding chemicals to your compost.
While the dyes may not be harmful, there isn’t really a way for an individual to check this.
Equally, cardboard that has got glue on it is a bad idea to add, and should have the glue torn off first.
Glossy paper, such as that found in magazines, should also be discarded in the recycling bin, not added to your compost.
Twelve: Biodegradable Packaging
This might surprise you, but it’s really important not to just toss biodegradable packaging into your home compost without checking it thoroughly first.
A lot of biodegradable packaging will only break down in commercial composters that reach a certain temperature, and will linger in your home compost heap indefinitely.
That’s why you should always check the labeling first.
While many firms are starting to offer packaging that is genuinely home compostable, there is a lot of misinformation and bad labeling around.
Be careful about “biodegradable,” and instead look for “home compostable.
You might count this under “meat,” but just in case you’re wondering, bones shouldn’t be added to the compost heap either.
They might not rot or attract flies, but they will attract other pests, and they won’t really break down.
If you want an alternative use for bones, consider boiling them up to make stock, and then throw them in the garbage.
They can’t be composted at home, even if the nutrients would make a valuable addition to your garden.
You might not have thought of adding feces to your compost bin, but whether you have or not, don’t do it.
This goes for both pet waste and human waste (not that you are likely to have human waste in your kitchen).
Feces will break down as they are organic, but the waste from both humans and carnivorous (or omnivorous) pets can carry dangerous pathogens that do not belong in your compost bin, especially if you use the compost for food crops.
The waste from things like guinea pigs, hamsters, chickens, etc., is fine to add, but cat, dog, and human waste needs to be kept out of the composter, or put in a dedicated compost that has no chance of contaminating food crops.
Fifteen: Cleaning Products
You should avoid adding any cleaning products or foods heavily soiled by cleaning products to your compost heap.
This goes for things such as washing up liquid and stronger cleaning products such as bleach.
These will kill off the useful bacteria in your compost, upset the worms, and generally make the whole bin nonviable, at least for a while.
Do not add cleaning products to the compost.
Sixteen: Diseases Organics
If you have certain diseases on the organic waste from your kitchen, don’t add it to the compost.
An example of this might be the blight on tomato plants.
This can stay alive throughout the composting process and infect future crops.
Vegetable scraps are fine, but you don’t want to be introducing dangerous diseases to the compost heap.
If you are concerned about this, especially if you compost at cold temperatures, avoid adding vegetable waste that looks sickly or odd.
This should be disposed of in the general waste instead.
Seventeen: Dryer Lint
Plenty of people recommend putting dryer lint or fluff from a vacuum cleaner into the compost bin, but this should be done with caution because it’s a common source of microplastics.
While the fluff may look innocent enough and disposing of it outside could seem a better alternative to putting it into landfill sites.
Bear in mind that there will be millions of tiny plastic particles from your clothes and the objects around your home.
If you only wear natural materials and only have natural material carpeting in your home, this kind of fluff may be a reasonably safe addition to a compost heap.
There may still be some contamination, but it should be minor. However, if you have synthetic clothes or carpeting, do not put the fluff in your compost heap.
Eighteen: Pet Fur
Pet fur is another “maybe” because if you don’t treat your pets with commercial flea treatments, it should be okay to add their fur to your compost heap.
However, if you use spot-on wormers or de-flea treatments, you might not want to add the fur.
Remember that these treatments are designed to cling to the coat and have a lasting effect, so they may negatively impact your compost bin if they are added to it.
It is safer not to put pet fur in the compost bin if it has chemicals on it.
Nineteen: Inorganic Materials
This might sound very obvious, but inorganic materials don’t belong in your compost heap.
Do not add even inert inorganic materials like glass; they won’t decompose, and they could pose a hazard when you’re handling the compost.
Ceramic, glass, plastic, metal, and other manmade materials do not belong in a compost heap, and should be kept in the kitchen or disposed of in the recycling or general waste bin.
Twenty: Cotton Swabs
Cotton swabs are not an organic material, even though the tips of them are (often) made from cotton fibers.
The stems of many are plastic, and therefore cotton swabs should not be added to your compost bin, even if they are not contaminated with chemicals.
You can purchase cotton swabs with compostable stems, however, and these are a good option if you want to compost your cotton swabs.
Some are made of bamboo, while others use cardboard or paper.
You should still think about what a cotton swab has been used for before adding it to the compost.
If it has been in contact with chemicals, dispose of it in your normal garbage, rather than adding it to your compost bin.
Twenty-One: Cooked Food
Although this is a broad category and can therefore be used more as a rule of thumb than a hard line, be wary of adding cooked food to your compost bin.
Like other “bad” foods, it is likely to attract attention from scavengers.
Cooked foods tend to have a stronger scent than raw foods, and may appeal to rodents and other scavengers.
If you are trying to avoid drawing attention to your compost bin, do not put cooked foods in it.
In small quantities, cooked foods can be added, particularly if you bury them near the bottom of the heap.
You can also look into bokashi composting, which is a system for processing cooked food waste so it can be composted.
However, you should avoid adding a lot of cooked food to your compost heap.
Hopefully, you now have a better idea of which things should be kept out of a standard compost bin.
If you avoid adding these things or at least keep quantities low, your compost will be happy and healthy.