Composting is easy – it’s a no-brainer and it doesn’t take much space! Or, so says your granola neighbor anyway.
But, it is easy – once you know the general rules. There are composting techniques and dos and don’ts – hings can go awry quickly if you’re not sure what makes good compost. It’s tempting to simply toss all your kitchen scraps into the backyard compost pile, but that’s a serious beginner’s mistake.
Let’s walk through some of the most common kitchen and household items you might want to compost, along with a few interesting items you might not have thought about. We’ll break it down by category.
What You Can Compost versus What You Can’t
Did you know you can have catastrophic results if you add the wrong things to your compost pile? It’s a living breathing ecosystem and needs to be treated as such.
Not sure why that’s so? Learn more about what compost is here.
Don’t worry though, anything you could think of tossing into your compost bin has been considered and thoroughly vetted for this guide. If you do find something we didn’t cover, then just let us know in the comments.
Composting Everyday Kitchen Waste
This is the stuff that ten years ago you would’ve thrown into your kitchen trashcan without a care in the world. In 2020, however, you have to know – what kitchen waste can be compostable?
First off, have you considered vermicomposting (or composting with worms)? It’s a great way to keep your kitchen waste out of a landfill. You can also help the environment by using your compost to grow crops. You can then use the food waste from the crops to power your compost pit for the following season – it’s a cycle!
Don’t worry we’ve covered it all for you in terms of what you can compost – from your morning cup of joe to your indulgent after-dinner dessert.
Can you compost coffee grounds?
Coffee grounds are one of the best things you can start to compost. Their texture helps aerate the compost and earthworms love them. They’ll help keep you compost full of beneficial microorganisms. They’re also super simple to compost—just toss ‘em on!
Every once in a while someone asks if you can use unbrewed coffee grounds for compost. First of all, are you crazy?! Why are you tossing perfectly good coffee?
But secondly, that’s not a big problem, although it can mess up the pH balance of your compost, since coffee is very acidic (before it’s brewed). Just don’t over-do it.
One word of warning: if you’re a two-pots-a-day kind of coffee drinker, be careful not to overload your compost with only coffee grounds. Make sure you’re maintaining a good mix of compost ingredients, including brown (carbon) materials. (Coffee grounds are actually a “green” nitrogen-rich material.)
Can you compost coffee filters?
This depends on what your coffee filters are made of. Is the filter made of natural fibers (paper) or does it contain synthetic fibers (like a type of plastic)?
If the entire thing is synthetic, it won’t break down at all. You’ll see it hanging around in your compost pile long after everything else has decomposed into black gold. If this happens, you can simply pick it out of the bin.
But if the filter is made of a combination of synthetic and natural fibers, you may not even notice. The natural fibers will break down, but tiny bits of synthetic fibers will remain mixed into your otherwise healthy compost. Not cool.
Lastly, are they made with icky chemicals like bleach or chlorine (I hope not, but some are)? If so, you don’t want that in your compost. And you don’t want that in your coffee cup, either, so go ahead and get some new, unbleached coffee filters.
Can you compost tea bags?
Yes, but check out the advice above about coffee filters, because it also applies to tea bags. But there are a few more things to think about with tea bags in your compost:
Does the bag have a staple? If so, remove it!
Is there a tag, and if so, is it made of unbleached paper? Some tea bags have plastic tags, or paper tabs with lots of colored ink on them. Those aren’t good for compost, so pull those off and trash them, too.
Can you compost loose tea leaves?
Yes! Go for it!
Can you compost raw eggs?
Okay, you can definitely compost raw eggs. But I’m not going to recommend it because of the stench and pest (bugs) issues.
Some people are worried that raw eggs may corrupt their compost with dangerous bacteria that sometimes live in raw eggs like salmonella with corrupt their compost pile, but this isn’t actually an issue, as anything dangerous will be killed off during hot composting.
Can you compost egg shells?
Egg shells are a fantastic addition to your compost. They add valuable calcium for plants and give it great texture.
You’ll want to crush egg shells before tossing them in the compost, though, to help speed up their breakdown. “Un-crushed” eggshells will certainly compost eventually, but it takes a lot more time, causing stinky compost and attracting pests. You can also rinse eggshells before composting, to avoid those bothersome possibilities.
Can you compost onions? What about garlic?
Yes, but beware of a few issues.
First of all, onions and garlic are smelly—as you well know. If it stinks on your kitchen counter, it’s going to stink in your compost. This won’t be too much of an issue if you regularly empty your kitchen counter compost container, but if your onion/garlic scraps sit around in your kitchen for more than a day, things are going to get very fragrant. For this reason, onions and garlic aren’t ideal for indoor worm compost bins.
Second, don’t throw huge chunks of raw, whole onions and garlic into the bin/pile. Not only will they take a very long time to break down (remember the stink), but raw onions and garlic can start sprouting and growing. Not an inherently bad thing, since you’re aiming to grow a garden after all! But you don’t want that garden growing inside your compost pile.
The last thing to consider when composting onions, in particular, is that the skins are quite tough, and need a very long time and a well-functioning compost system in order to break down.
Can you compost potatoes?
Seems like a silly one, right? But just like onions, whole potatoes can regrow in the compost environment. You’ve probably seen raw potatoes (eyes) start growing little tendrils and sprouts even as they sit on your kitchen counter.
Just chop big pieces up so they break down quicker and don’t sprout.
Can you compost root vegetables?
Yes, but with some caveats.
You’re probably getting this idea from the tips about onions, garlic, and potatoes that root vegetables are no problem to compost, but they can all start to sprout in the pile. Just cut them up into smaller pieces and toss ‘em in.
(Cooked, they are no problem. But see below about oil, dairy, and other no-no materials that may be combined with cooked veggies.)
Can you compost citrus?
Yes, but in moderation.
Too much citrus can mess with the pH balance of your compost heap. Too acidic, and good bacteria in your compost could be harmed. Plus, worms don’t love the chemicals found in citrus, especially lemons.
Citrus peels also take a long time to decompose. (After all, that rind is a strong protective layer for the inner fruit.) Citrus rinds are okay, but not too many. Too many will clog up your compost.
If for some reason you’re throwing away a whole citrus fruit, cut it up to aid decomposition.
Can you compost banana peels?
Oh heck yeah, banana peels are a compost pile’s dream come true. They’ll give you compost (and therefore you garden plants, and therefore you, if you’re growing edible crops!) healthy additions like potassium, calcium, phosphates, and more.
Can you compost whole bananas?
Sure, but why would you do that? Even a totally black-brown banana is great for a smoothie or frozen like a popsicle.
Can you compost fruit pits?
Yes, but fruit pits take forever to compost. And they’re meant to sprout. Just something to note.
This goes for seeds, too. It isn’t uncommon for someone to throw an avocado pit or a tomato scraps into the compost pile and find a little baby tree/sprout in a few months.
Can you compost oils and fats?
Oil is a nightmare for a healthy composting system. The chemical war between water and oil will wreak havoc on your compost pile. Oil will coat other compost materials with a water-resistant barrier that stops airflow and moisture retention.
That will severely mess up the moisture balance of your compost and slows or halt decomposition. What do you get in an anaerobic compost pile? A lot of stinky garbage, and no fresh compost for the garden.
This includes avocado oil, sunflower oil, olive oil, and all other cooking oils—yes, even coconut oil.
It’s okay to compost very, very small amounts of oil, but it is best to avoid it altogether.
Can you compost dairy?
Dairy is animal fat—see above! Fats (lipids) hate water and air, and compost needs both to flow freely.
What’s more, dairy is the worst culprit of mold and stench. Dairy does biodegrade, but it’s not a pretty process, and it takes a heck of a long time. (Where do you think Bleu cheese comes from?)
This includes butter, which fits in both the oil/fat and dairy categories. Double no-no!
Can you compost bread and bready items (i.e. pasta, etc.)?
This is a point of great contention in the composting world. Yes, bread can be composted. But here are some things to keep in mind:
Bread will greatly affect the moisture content of your compost (by soaking up moisture).
Bread gets moldy very quickly, which is bad for your compost.
Bread attracts pests very easily.
If there’s live/active yeast in the product, the yeast will “stay alive” in the compost and thrive, which isn’t ideal for the health of your microbes.
Ditto above for the loads of chemical sugars in bread. They can form a breeding ground for bacteria.
For these reasons, stale bread or a small amount of crusts are your best bet for compost, rather than huge pieces of loaves or already moldy slices. It is also best for an enclosed bin, rather than an open-air pile or trench.
Can you compost walnuts?
Yes, but you need to know some things first.
Huh? Walnuts?! Why would they be an issue?
Walnuts contain a chemical called juglone that can be toxic to some vegetables and plants. A handful of walnut shells isn’t going to cause a huge problem in a big heap, but don’t chuck a giant amount of walnuts and shells onto your compost.
Composting Other Household Waste
Yes, composting isn’t just limited to food products. Think about it, the last time you went to a hip coffeeshop, did they have a composting option? Here in Denver most definitely do.
Check out this list to see how much of your household trash you could keep out of a landfill!
Can you compost paper?
Yes, but not all paper.
Paper is excellent “brown” (carbon) compost material, with some caveats.
You’ll want to stick to these guidelines when putting paper products into the compost:
- No color newsprint
- No magazines
- No other glossy or coated paper
- Nothing with “extras” like shiny foiled, glue, or glitter (yuck!)
- No produce stickers
Can you compost a cardboard paper towel or toilet paper tube?
Another excellent brown compost ingredient. Just shred them up before setting a thin layer on your compost.
Can you compost other cardboard?
Like paper, cardboard can be a good source of carbon for your compost cocktail, but with a few caveats.
There are many different kinds of cardboard, and some aren’t good for compost. Regular thin, flat cardboard/paperboard like cereal boxes and
Follow these rules of thumb:
- Avoid wax-coated cardboard
- No greasy, cheesy, or food-soiled cardboard
- No foil-lined cardboard (like pet food or litter bags/boxes)
- No stickers or labels
Composting Yard Waste
Can you compost sawdust?
Yes, but only add sawdust from non-treated wood. Do not include painted, stained, or veneered wood, which will put chemicals into your compost.
Be sure not to carelessly dump a huge amount of sawdust on top of your pile—it will form a non-aerated layer that will do all kinds of bad things to your compost.
Can you compost leaves?
Just remember that they should be dry, and that certain kinds of leaves may contain naturally occurring chemicals that aren’t good for certain garden plants or disrupt the pH balance of your compost.
Before adding a huge amount of a certain type of leaves to your compost, just use Google to check if that type of tree leaf contains anything that will harm other plants or soil.
Can you compost garden weeds?
Yes, but pull off the root systems first!
Don’t throw weeds with intact root systems into your compost—they’ll just sprout up in the nice, healthy home you are making for them! The best way to compost weeds is to let them sit out in the sun for a few days, die, and dry up. Then chuck them onto your pile.
DO NOT throw infected weeds onto your compost. Disease in a compost ingredient will become disease in your compost pile, and then disease in your garden.
Can you compost grass trimmings?
Grass trimmings from your lawnmower (or scissors, if you like a really precise yard trim) are the perfect “brown” compost ingredient.
Composting Animal Items
Many people steer clear of any and all animal products in their household compost, simply because composting this type of material can get messy, tricky, and potentially hazardous.
Can you compost animal waste?
Yes, but not recommended.
Of course, composting manure, including chicken manure, is a traditional part of farming and composting, but it’s very tricky and takes a lot of attention.
Animal waste carries a lot of dangerous parasites and microorganisms, and if you do not carry out a thorough, balanced hot composting process, those nasty things won’t get killed. Only compost animal waste if you have a really big, well-functioning hot compost pile that you are careful managing by turning and temperature-taking.
DO NOT compost pet waste that has been in contact with something like kitty litter.
Can you compost meat?
Like manure, meat just carries too many possible pathogens to be a safe compost material.
Meat also takes a very long time to break down and, in the meantime, attracts all sorts of yucky (and potential dangerous) pests and intruders. This includes cooked meat.
Can you compost carcasses?
No, but yes.
A “but” about it? I thought I just said no meat? Indeed, processed and especially cooked meat is in a very different state than an animal that has just died of natural causes. There are ways to safely and effectively compost animal carcassess, but that’s a discussion for another time.
For now, just steer clear!
Can you compost bones?
Bones will not break down (duh).
Plus, they can attract pests like rats, racoons, and coyotes. Even worse, if your backyard pup gets into your compost and gets a hold of a small bone like a chicken bone, she could choke.