What Not To Compost: 33 Things You Shouldn’t Put In Your Compost Bin

We’ve already covered what is compostable, but learning what not to put in a compost bin is equally important. Certain items—some food scraps and organic waste included—can spoil your efforts or at least inhibit the process. In the worst-case scenario, you could contaminate the whole heap. A waste of all that waste!

Our list of is broken down (pun intended) into sections based on different locations around the home, including what food is not compostable and what yard waste should be kept out of your pile or bin.

Learning how to compost as much of your waste as possible is a wonderful way to embrace low-waste living. As you read through the list of things not to compost, think about how to reduce, reuse, or recycle those items instead. We’ll provide some tips.

So, what should you not put in compost?

Let’s dig in.

Our “what not to compost list” begins in the kitchen. If you’ve ever wondered what vegetables should not be composted or what other food items to leave out, this is a good place to start.

1. Meat, fish, and bones: Meat scraps are probably the biggest “composting don’t” as far as food waste goes. A few specialized composters can handle these items, but your run-of-the-mill compost pile or bin can’t. Rotting meat and fish smells bad! And anything that stinks will attract unwanted pests, like raccoons, rodents, and maggots. If you don’t have a specialized composter, you can send meat scraps for commercial composting.

2. Dairy products and eggs: As dairy products break down and ferment, they’ll also start to smell. Like REALLY smell. Like rotten eggs and sour milk smell! Which pests and scavengers love.

3. Butter, cooking oil, animal fat, and grease: Oil and water just don’t mix. Since moisture is a key component of the composting process, these non-compostable food waste items won’t break down. Instead, they’ll shift the moisture balance of your pile and attract pests. This includes paper towels saturated with grease—though you can otherwise compost paper towels.

4. Fat-based condiments and foods: Things like oily salad dressing and peanut butter will not break down any better than straight-up fats, for the same reason as #3.

5. Citrus fruit peels: Aside from taking a long time to break down, putting acidic citrus peels in compost risks throwing off the pH of your compost bin and slowing the overall decomposition process. Composting citrus is especially forbidden if you have a vermicomposter because it can kill your hardworking worms. Instead, use citrus peels to make your own DIY cleaning products.

6. Onions and garlic scraps: As with citrus food scraps, putting garlic and onion in compost can kill worms and other beneficial composting organisms essential for breaking down organic matter. While they are not recommended for vermicomposters, they should be fine, in small amounts, in your regular compost pile, provided they’re balanced with other items. You can also save them in the freezer with other vegetable scraps to make your homemade vegetable stock.

7. Baked goods and cooked grains: No rice or freshly baked bread products, especially confections with glazes or high sugar content. Both breed harmful bacteria and attract rodents. Cooked rice is especially notorious for growing bad bacteria in a compost pile. Plain bread that’s stale and hard (the only type of bread you should compost), as well as uncooked rice and pasta can be composted in moderation. Just be sure to bury it as deeply as you can.

8. Coffee pods and tea bags: While composting coffee pods is a pretty obvious no-no, tea bags may seem harmless. Unfortunately many are made of food-grade PET (AKA plastic) or nylon fibers that, at best, will not break down and, at worst, contaminate the whole pile. Coffee grounds and tea leaves, however, are excellent sources of nutrients for compost, so remove them from their bags and pods. Better yet, switch to loose-leaf tea and zero waste coffee makers like a moka pot or French press.

9. Stickers on fruits and vegetables: These bits of plastic are easy to miss, but make sure you peel them off before tossing that banana peel in your pile. They don’t even break down in industrial composting facilities, let alone your home one. They’re a huge source of composting contamination all over the world. You can eliminate your consumption of these annoying stickers by buying directly from farmers at farmer’s markets.

10. Coated cardboard packaging: Any food packaging with either a plastic or foil layer is unsuitable for your compost pile. This means waxy-lined paper cups, milk cartons, juice boxes, foil-lined paper snacks, crackers, and cookie bags. Takeaway coffee cups are also generally not compostable (or recyclable).

11. Bioplastic packaging and cellophane: Beware of any “biodegradable packaging” unless you know for a fact that it’s certified to be home compostable. Many of these are only compostable in industrial composting facilities (which get far hotter than your home compost pile). Talking of bioplastics, be sure to read up on compostable and biodegradable trash bags before you toss them in the worm bin or compost heap. They’re often not as green as they say they are.

12. Large branches or pieces of wood: These take forever to break down so must first be chipped into small pieces.

13. Coal and charcoal ash: No charcoal from the grill. While wood ashes are safe to mix into your compost pile, coal ashes are not. They contain harmful substances like arsenic and mercury, which can contaminate your garden with the finished compost.

14. Naturally toxic plants: Avoid Oleander leaves and anything from the black walnut tree (including walnuts themselves), which contains juglone, a naturally toxic compound for plants.

15. Treated lumber: Any lumber intended to be used as building materials is usually treated with water-repellent coatings that contain toxic chemicals. Because they’re resistant to moisture and, thus, biodegradation, they’ll also take a long time to break down. This includes sawdust from treated wood.

16. Tomato fruits: Tomato plants and trimmings are fine, provided they are not showing any signs of diseases. Technically, the fruits are fine, too. But unless your compost bin or pile is hot enough, the seeds can survive and lead to baby tomato sprouts anywhere you use the compost. Instead, use your overripe tomatoes to make some yummy salsa!

17. Synthetic fertilizer: Don’t dump remnants of fertilizer or even soil recently treated with large doses in your pile. Synthetic fertilizers may do a few things to compost: kill microorganisms (slowing down the pile’s decomposition rate), alter the pH and nutrient levels, and eventually leach into the ground.

18. Lawn trimmings recently treated with pesticides or herbicides: Grass often has some degree of chemical treatment. The composting process is pretty well suited at breaking those materials down harmlessly, but only in small amounts. Since lawns are typically treated in high concentrations, a freshly treated lawn shouldn’t go near your compost until the concentration has had time to weaken and dilute. Give it a few weeks. Better still, practice ecological gardening and do away with chemical inputs altogether.

19. Diseased or insect-infested plants: Plants affected with disease or insect infestation aren’t good compost material. Unless your composter gets really hot, there’s no guarantee these things will be killed. If they’re not, you could spread diseases around with your compost.

20. Weeds gone to seed and invasive plants: Dandelions and ivy, for example, are persistent weeds that will sprout in your compost pile and spread to wherever you use the compost.

21. Cigarette butts: Some are made of plastic, but that aside, cigarettes are filled with chemicals. Even natural tobacco is problematic as nicotine is an insecticide, and tobacco can also harbor the tobacco mosaic virus, which can potentially pass to other plants in the same family, including tomatoes, peppers, and eggplants.

22. Synthetic soaps: Soaps shouldn’t go in your compost unless made entirely from natural ingredients or certified as biodegradable (and thus safe for the environment). Even if you have a tiny sliver of standard bar soap left over, you’re better off collecting it, and once you have a few, melt them together to make a new bar.

23. Used feminine hygiene products: Only organic pads and tampons made from 100% natural materials should be composted. It’s also generally not recommended that you add them to your regular compost. Anything with blood can contain hard-to-kill pathogens, which can transfer to your compost. However, you can use certain types of composting, including hot composting. You can go add reusable cotton pads and liners to your bin (after they’ve been washed).

24. Humans feces and diapers: Like blood, human feces poses a significant health risk and can contain diseases and parasites. There are various humanure (human manure) systems and compost toilets that can safely recycle poo, but your regular home compost bin isn’t one of them. Most disposable, biodegradable nappies are not yet home-compostable, but you can compost wet (non-poopy) diapers if they are. As with reusable liner pads, you can compost reusable diapers, provided they’re made with 100% natural fabrics and they’ve been washed.

25. Vacuum cleaner contents: The tiny plastic or synthetic fibers carpets constantly shed could contaminate your compost (as well as the odd price tag connector or LEGO piece that gets sucked up).

26. Dryer lint: Dryer lint contains various fabrics and can contaminate your pile. Even if you only dry 100% cotton clothing in a separate load, the lint could still contain synthetic fibers from previous loads.

27. Synthetic fabric of any kind: Synthetic fabrics can contain all sorts of harmful chemicals and dyes. Even if your t-shirt is 99% cotton and just 1% polyester, it can’t be composted.

28. Leather goods: This means worn-out belts, wallets, purses, gloves, etc. Due to oil finishes and unknown chemical ingredients, i.e., additives, dyes, and chemical tanning agents, it’s best to keep leather out of your compost bin. Not only are these ingredients potential contaminants, but they also mean that the leather will take a long time to decompose. Most vegan leather also can’t be composted as it’s often a plastic-based, non-organic material. Exceptions include things like 100% natural cork fabric.

29. Paper with lots of color printing or Sharpie-drawn inks: Colored printer ink and markers such as Sharpies can contain heavy metals and other toxins. Anything saturated with these can contaminate your compost.

30. Glossy Paper: Any paper with a glossy plastic finish is toxic to your compost pile. This, unfortunately, means some magazines, product catalogs, most wrapping paper (unless it’s zero waste or eco-friendly wrapping paper), and photographs.

31. Dog and cat feces and litter: Carnivorous and omnivorous animals’ intestines can host to a wide range of resilient parasites and pathogens. Cat poop is especially dangerous. This type of animal waste must be composted separately in special, high-temperature pet waste composters. (More about this in our zero waste dog article). Manure from other purely plant-munching pets or livestock, however, is very beneficial.

32. Manure from sick animals: Herbivorous or not, any sick animal can pass on harmful bacteria and viruses through their excrement.

33. Dead animals: One of the more interesting composting facts is that it’s legal to compost human remains in some states, but that doesn’t mean you should try to compost your beloved fur family members. As with meat, dead animals will stink, attract pests, and grow potentially unwanted pathogens.