What Not To Compost: 20 Things You Can’t Compost
Anything that once lived can usually be composted, but modern day life is complicated – things often aren’t what they appear.
Figuring out what may biodegrade well is confusing, to say the least.
This guide aims to cover both the obvious and more complicated things not to put in compost, backed up by lots of trial and error testing.
You’ll find the items listed here loosely organized, by material type or other categories.
So, what can’t you compost?
20 Things You Can’t Compost At Home
At the end of the day, the point of your diligent backyard composting efforts is to produce rich fertilizer and soil for your garden. This isn’t a process that should take years, or even months – if you follow a proper composting schedule you can have an easily spreadable, fertile pile of goodness in a matter of days to weeks.
Because composting is an essential step in learning how to start a garden, avoiding adding a relatively strict list of things to your compost is something you should think about doing.
It makes composting painless, and should effortlessly increase the biodiversity in your garden. We’ve also written a guide covering what is compostable, so make sure to check that out once you’ve read this one.
Keep in mind that industrial composting facilities will be able to process certain materials that your home setup may not be able to handle, so we’ll make a note of those.
1. Plastic packaging
In the natural world, plastic simply breaks down into microplastics – avoid at all costs.
Since this guide is mainly written for those composting at home, it’s best to avoid adding bioplastics to your compost bin. In general, bioplastics require industrial composting facilities to properly biodegrade – your home compost system simply won’t do in most cases and plant-based plastics will take much too long to break down.
And just to be clear, this probably includes your biodegradable garbage bags which are more suited to collection from your local green waste pickups.
3. Produce stickers
The produce stickers found on fruits and vegetables are considered “edible” by organizations like the FDA, but they’re still made from a combination of paper and plastic, and are non-compostable. Make sure you take these off any peels so they don’t end up in your soil.
4. Certain fruits and vegetables or peels
This is more of a suggestion than a hard no, but sometimes organic waste scraps like avocado peels can be tough to fully compost at home, so feel free to toss these in your green collection bins or cut them into small pieces before composting them.
Citrus and banana peels can be a pain too, but avocado sticks around the longest in our experience. If you’re sensitive to smells, you may not want to compost onions, garlic, and other fragrant plants in large amounts.
5. Tea bags and coffee filters
Knowing what your coffee filters and tea bags are made out of matters if you’re trying to compost them – it’s not always simple paper filtering and both products can be made from plastic. Eliminating these from your life is one of our simplest tips for those learning how to avoid microplastics.
6. Most paper products
Not all paper is created equal, and most paper that’s safe to compost will be labeled as such. Adding things like grocery receipts – which contain petrochemicals like BPA – will only introduce harmful additives into your food supply.
Dyes, bleach, and plastic added for tensile strength are all things to watch out for when composting paper. If you’re unsure of where the paper is from, don’t add it. Recycle it instead! Also – some brands of compostable paper towels are still hard to deal with in large amounts when added to a backyard compost pile.
7. Most cardboard packaging
Similar to paper products, cardboard is better left for recycling. Some brands do use boxes made from cardboard you could compost in small amounts, but it’s simply just not worth the risk of using treated cardboard.
Cardboard often contains harmful additives that complicate the process of composting, and in general aren’t things most living creatures want to be around (including humans).
8. Personal care waste
Things like tampons, cotton swabs and rounds, toilet paper, and other personal care waste shouldn’t be added to composting piles for the same reason as pet waste – humans are pretty filthy animals, and adding things your body is trying to get rid of into your garden isn’t the best idea.
Sunscreen, for example, often contains UV filters that are thought to be contributing to coral bleaching events in certain areas of the planet.
9. Sanitary and cleaning wipes
Even if you’re buying wipes labeled as flushable or biodegradable, you generally don’t want to try to compost things that will take such a long time to break down. Even bamboo-based wipes, or wipes without petrochemicals should be avoided, although these may be able to biodegrade but require industrial composting.
10. Dust, pet hair, vacuum and dryer lint
You’d be wrong to assume that lint from your dryer, dust in your home, and even pet hair you’ve swept up or vacuumed will biodegrade.
Unfortunately, these fluffy, innocent looking piles are often mostly microplastic fibers from clothes and should be thrown in the trash. Not all fabrics produce microplastics, but you would have to check the tag from each individual article of clothing to be sure.
11. Old clothing and fabrics
Most modern-day fabrics include some amount of synthetic thread weaved in, which means introducing plastic or bioplastics that home compost microorganisms won’t be able to deal with effectively. If you insist on trying to compost fabrics, it may require industrial composting.
Some fabrics like cotton, hemp, wool, or linen could technically be composted – but again, the point of a home compost pile is to have a nutrient-rich spread relatively quickly, and there may be better uses for old fabric.
12. Meat scraps and animal bones
While you can compost animal products like meat scraps, animal bones, and other similar waste products to your compost bin, there are a few issues with it:
- Animal scraps smell incredibly foul even after a short period of time
- Pungent smells attract pests and scavengers like flies, rats, and even raccoons or bears to your bins
- Decomposing meat can become contaminated with bacteria like E. coli, and spreading infested compost can transfer it into your garden
If you’re trying to get rid of some old plant based meat, however, feel free to add it!
13. Grease, fats, and some oils
Along the same line as animal meat and bone, composting leftover oils from cooking and prepping food is generally a bad idea. Things like avocado and olive oil are much easier to deal with and shouldn’t cause the same issues as animal-based oils.
Still, having an excess of oil in your compost bin can create a bit of a mess when spreading it around or turning it.
14. Food containing animal ingredients
Things like baked goods, sweets, and milk-based products will spoil fast in your compost bin and attract unwanted pests much faster than other organic waste. It’s better to just eat these products before they spoil, or learn how to go vegan to avoid the problem entirely.
15. Human waste and poop
Human waste both smells terrible and is an easy vector for disease to spread throughout your garden and property. Many of us take daily medications or use products that leave our bodies via our waste, and there’s really no reason to risk ruining your hard-earned compost with any of that.
Some composting experts may choose to add their waste, as circular compost designs are promising, but if you’re new enough to be questioning what to add in general you’ll want to skip this for now.
16. Pet litter and poop
Similar to human waste, aside from introducing potential bacteria and disease into your compost, modern-day pet waste can contain a variety of things you wouldn’t want spreading throughout your garden.
Medication is one concern, as pet waste would be no different from spreading your own bathroom surprises amongst your tomatoes.
17. Invasive or diseased plants
Whether you’re clearing fast-growing weeds or purging dying houseplants, you’re going to want to avoid adding unwanted plants to your compost bin to avoid spreading disease or encouraging more weeds to sprout up.
18. Pesticide treated plants
If you live somewhere where spraying pesticides is common (so pretty much everywhere), how you dispose of weeds or dying plants becomes more important.
Pesticides not only kill insects that devour your crops – introducing these persistent chemicals into your compost bin can also kill pest predators, pollinators, and even beneficial microorganisms you don’t want to miss out on.
19. Lumber and bulky yard waste
Lumber is similar to cardboard and paper in terms of being treated with chemical solutions. Aside from that, lumber and large branches, bunches of leaves, or composting hay or lots of grass clippings might overwhelm your pile. There’s no point in maintaining all of this if it doesn’t fertilize your garden, so don’t try to compost all your yard waste.
20. Gasoline, motor oil, and petrochemicals
While this should be obvious, never directly add petroleum products to your compost. Gasoline and related products will directly destroy and contaminate your compost – all of these substances are highly toxic to plants and animals.
Composting shouldn’t be very hard – and the easiest way to succeed at it is to keep a simple list of things you shouldn’t compost handy.
Thankfully, most of the things you don’t want to add to your home bins are pretty obvious!
Do you have any thoughts on what can’t be composted?