20 Things You Shouldn’t Compost at Home

If you’ve recently started composting and are getting ready to throw anything and everything in your bin, all willy-nilly, don’t There are a ton of things you need to avoid putting in your bin. They either won’t break down, will smell horrible, or will attract pests and animals to your property. Composting can be delicate initially, and if you’re not careful, you might ruin your hard work. Familiarize yourself with this list of 20 things you shouldn’t compost, and you’ll avoid any issues. 

Things You Shouldn’t Compost

1. Meat

Meat never does well in a compost pile. There’s a reason dead animals smell so horrible; they don’t break down like a pepper or a piece of paper in nature. Any meat, cooked or uncooked, that you add to a compost pile will begin to rot and smell horrible. It’s also likely to attract raccoons or other animals in search of a free meal. You can either give your leftover/unused meat to Fido or dispose of it with the rest of your garbage.

2. Fish

If meat doesn’t do well, neither does fish. Fish might even smell worse in a hot compost pile. Fish and meat are both rich in fats; fats have a hard time breaking down in a compost pile and will turn rancid instead of turning into nutritious soil for your plants. 

3. Bones

While eggshells are great for compost piles, bones aren’t. You might think they would be as beneficial as eggshells since they’re rich in calcium, but bones can take an impressively long time to break down. 

Fish bones can take a few months to break down in a regular, at-home compost pile, while larger bones from animals can take years. It’ll vary depending on the temperature and composition of your pile, but it’s generally a good idea to keep bones out. 

If you have a large enough bin, you might be able to get away with chicken bones, but until you’re confident in how quickly your bin can break scraps down, stick with the usual compost items.

4. Cooking Oil

Used fry oil should always be disposed of properly. Never pour it down your kitchen sink, outside on the ground, or add it to your compost pile. Again, it’s extremely fatty and won’t break down well in your compost bin. You can seriously affect the microbiome of your bin by adding fry oil to it. 

We suggest using a product like this oil hardener to deal with cooking oil. You just add a packet to your oil, and after an hour or so, it’ll solidify into a solid gelatin you can easily and safely dispose of in the trash.

5. Bacon Grease

Again, it’s too fatty. It’ll turn rancid in the heat of the pile, and you’ll have a very smelly pile of dirt and food scraps that is calling every scavenger in the area to come and dig around. You’re better off pouring your bacon grease through a filter into a jar and reusing it at a later date for a quick flavor boost. 

Bacon grease makes almost anything taste better, and it holds incredibly well. You can keep bacon grease in the fridge for a few months or in the freezer till the end of time (almost). Filter out any bits of food so that you just have pure fat. Spoon it out as needed, when needed.

6. Citrus Peels

Okay, this one isn’t a hard rule, but generally, you want to avoid adding too many citrus peels to your pile. Larger compost bins can handle more peels at a time than smaller ones, but the acidity in the peels can raise the pH of your pile to dangerously high levels for the microorganisms in the compost pile. 

An occasion peel won’t immediately kill your compost pile, but too many can wind up ruining your hard work. If you do have a lot of citrus peels, add them slowly and keep a close eye on the pile. If you notice it’s not working as fast as it used to, you might want to stop adding your orange peels. 

7. Onions

If you want to avoid smells that will make you gag, avoid adding onions to your pile. Besides the fact that they may start growing in your pile, they smell horrid when they begin to rot.  You can place them about a foot under the top of the pile, but when you go to rotate your compost, you’ll get hit with a stench so foul you’ll never want to put onions in your pile again. It’s also likely to attract animals that will dig through the pile, so it’s best to avoid it together. 

8. Garlic

Garlic is in the same boat as onions. They are compostable, but only if you can deal with the smell and keep your pile free from pests by using a fence or some sealed area. The papery exterior and the cloves themselves can break down, but don’t say we didn’t warn you.

9. Plastic Coated Products

It should be obvious that plastic has no place inside of a compost bin, but there are products out there that are plastic coated that many people overlook. Certain cups, disposable plates, and even tea bags can have thin plastic coatings to make them more durable. 

These products should not go in your compost bin as plastic can take thousands of years to fully break down in the soil. Check any paper goods or other household items for plastic linings before adding them to your pile.

10. Dairy

Like meat and fish, dairy products will go rancid and become odorous long before they fully break down. Items like cheese, milk, sour cream, and more belong in the trash rather than your conventional compost pile. Smells attract animals, and animals will quickly dig through and ruin your nice pile of compost.

11. Leftovers

This one depends on what exactly the leftovers are, but more often than not, you don’t want to add last week’s chicken parmigiana to your compost pile. If your leftovers are steamed broccoli or some other sort of cooked vegetable, you can definitely toss it in. Avoid adding cooked pasta, rice, and other leftovers that will smell and take a long time to break down. 

12. Bioplastics

On a similar note as plastic-coated products, products made from bioplastics aren’t inherently compostable at home. Sometimes, they’re not even biodegradable. Often these products have to be treated at industrial facilities before they can break down. Your compost bin at home isn’t fit to break these things down, and you’re better off leaving it to the professionals.

13. Styrofoam

Styrofoam is horrible for the environment and will do nothing for your compost pile. It will sit in it, refusing to break down. It’ll almost certainly outlive you and still be in your compost pile after you’re gone. 

Styrofoam needs to be disposed of properly according to your local waste management guidelines. You can easily use Earth911 to find out where your nearest recycling center or waste treatment center is for other products like batteries, computers, plastics, and more.

14. Liquids

While your compost pile should be moist, it shouldn’t be a soup. Adding things like juices, milk, plant-based milk, and other liquids should be avoided. It’s ok to occasionally wet your compost using water if it looks dry, but don’t think you can use old orange juice instead. The acidity and chemicals in the juice can mess with the microbiome you’ve so carefully grown.

15. Pet or Human Waste

People often think they can add their pet’s waste to their compost pile as an easy way to get rid of it. They also think it’s okay because farmers utilize manure as a natural fertilizer, which is true, but the manure used on farms differs from the excrement your dog or cat is leaving around your yard.

Fresh manure is also extremely smelly. There’s a reason you can tell which farm fields were freshly fertilized, and there’s a reason every farm with manure has that same distinct smell. If you don’t want a smelly pile of compost, don’t add waste to your piles.

Manure also has the possibility of containing dangerous pathogens that can be harmful to humans. Unless you know what you’re doing and can properly treat your manure to kill these pathogens off, you should avoid adding pet or human waste to your residential compost pile. 

16. Certain Tea Bags

Some tea bags are coated in plastic and will not fully break down in your pile. Check to see if yours do. You should also remove the staple that is commonly used to hold the string and tag to the tea bag. You don’t want to spread tens of little staples all over your garden. 

17. Fatty Condiments and Foods

We’ve said it a few times— fatty products are not good for compost piles. Something like peanut butter, mayonnaise, and other fatty foods will not break down in a reasonable amount of time in your compost pile. They’ll also smell as they sit in your pile, attracting animals and pests. 

18. Large Pieces of Wood

Wood will break down over time, but the larger the pieces of wood are, the longer they’re going to take to break down. If you do have to add wood to your compost pile, break it down into chips first to help speed up the process.

19. Treated Wood

Treated wood, like 2x4s from your local hardware store, are not good additions to your compost pile. These planks have been specifically treated to withstand the elements and will have a hard time breaking down in your bin. They also can leech out chemicals that aren’t great for the microbiome of your bin.

20. Plants and Clippings that have been Treated with Pesticides

Grass and plant clippings are definitely okay to add to your compost pile. They’re a great source of nitrogen and are an easy way to balance out your compost pile’s carbon-nitrogen ratio. That said, if you treat your lawn or plants with pesticides or herbicides, you should definitely avoid adding them to your compost bin immediately after trimming. 

We suggest leaving them in a separate pile, giving time for the pesticides and herbicides to dilute to safe levels before adding them to your main compost bin. You’ll avoid killing the microbiome you’ve worked hard to grow but can still get the nutrients back out of your grass or plant clippings.