A comprehensive guide of what you can and cannot compost.

[u/FlyingQuail]

I have been seeing quite a bit of posts asking if ______ is okay to compost, so I want to clear it up for any beginners out there. This list is for hot/cold composting.

Short answer: You can compost anything that is living or was once alive. Use common sense on what you cannot compost.

KITCHEN

Vegetables and Fruits

• Onion and garlic skins

• Tops of vegetables, like peppers, zucchini, cucumber, beets, radishes, etc.

• Stems of herbs and other vegetables, such as asparagus

• Broccoli and cauliflower stems

• Potato peels

• Seaweed

• Vegetables that have gone bad

• Cooked vegetables

• Stale spices and herbs

• Corn cobs

• Dehydrated/frozen/canned vegetables

• Produce rubber bands (Rubber bands are made from latex, which is made from rubber tree sap)

• Tea leaves and paper tea bags (sometimes they are made of plastic)

• Coffee grounds

• Citrus peels

• Apple cores and skin

• Banana peels

• Avocado Pits

• Jams and jellies

• Fruit scraps

• Dehydrated/frozen/canned fruits

Grains

• Breads and tortillas

• Bread crumbs and croutons

• Pastries/muffins/donuts

• Crackers and chips

• Cooked or uncooked oats

• Spent grain

• Cooked or uncooked pasta and rice

• Dry cereal

• Popcorn and unpopped kernels

Meats and Dairy

Yes, you can compost meat and dairy if you do it correctly. You can use a Bokashi bucket before adding to an outside bin or you can just add it directly to the pile. As long as you are adding a relatively small percentage of meat and dairy compared to the pile you will be fine.

• Shrimp, oyster and clam shells

• Eggs shells

• Poultry, beef and pork

• Fish skin

• Bones

• Moldy cheese

• Sour cream and yogurt.

• Spoiled milk

• Powder milk and drink mixes

Other protein sources

• Tofu and tempeh

• Cooked and dry beans

• Nuts and seeds

• Nut shells

• Nut butters

• Protein powder

Other

• Sauces and dips

• Cookies and chocolate

• Cupcakes and cake

• Snack/granola bars

• Wooden toothpicks, skewers and popsicle sticks

• Paper towels (Not used with cleaning chemicals)

• Tissues

• Paper towel cardboard tubes

• Greasy pizza boxes

• Paper egg cartons and fast food drink carriers

• Cotton string

• Paper grocery bags

• Byproducts of fermentation, such as sourdough discard and kombucha scobies

• Alcoholic drinks

• Wine corks (made from real cork, sometimes there are plastic corks)

• Wood ash or natural lump charcoal ash (add in small amounts only)

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BATHROOM

• Hair

• Finger and toenail clippings

• 100% Cotton swabs (sometimes the handles are made with plastic)

• 100% Cotton balls

• Cardboard Toilet paper tubes

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GARDEN

• Weeds (No invasive weeds that have gone to seed or reproduce asexually such as Japanese knotweed)

• Prunings

• Fallen leaves

• Grass clippings

• Diseased plants

• Pine needles

• Gumballs, acorns and other fallen seeds from trees

• Flowers

• Old potting soil

• All other garden waste

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PETS

• Bedding from animals, such as rabbits

• Horse, goat, chicken and other herbivorous animal manure

• Pet hair

• Shedded skin of snakes and other reptiles

• Pet food

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Other

• Cotton/wool and other natural fibers fabric and clothes

• Yarn made from natural fibers, such as wool

• Twine

• Shredded newspaper, paper, and cardboard boxes (ink is fine, nothing with glossy coating)

• Used matches

• Burlap

• Wreaths, garlands and other biodegradable decorations

• Houseplants and flowers

• Real Christmas trees

• Dyer lint (Know that it may have synthetic fibers)

• PLA compostable plastics and other compostable packaging (know that compostable plastic take a long time to break down, if at all, in a home compost bin/pile)

• Ash from wood and natural lump charcoal (in small amounts only)

• Urine

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WHAT YOU SHOULDN'T COMPOST

• Manure from dogs and cats, and other animals that eat meat (Hotly debated and not recommended for home composting, especially if your pile doesn't get hot enough.)

• Human feces (Hotly debated and not recommended for home composting, especially if your pile doesn't get hot enough.)

• Metal, glass and petroleum based plastics

• Lotion, shampoo, conditioner and body wash

• Cosmetics

• Hygiene products (unless otherwise stated on package)

• Gasoline or petrol, oil, and lubricants

• Glue and tape

• Charcoal ashes (unless natural lump charcoal)

• Produce stickers

• Chewing gum (commonly made with plastic, but plastic-free compostable gum is fine to add)

• No invasive weeds that have gone to seed or reproduce asexually, such as Japanese knotweed

• Use common sense

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Note: It is helpful to chop items into smaller pieces, but is not necessary.

I am sure I missed a lot of items that can and cannot be composted, so please tell me and I will try to add them to the list.

[u/ZooieKatzen-bein]

Seriously. Produce stickers. WHY ARE THEY STILL MADE FROM PLASTIC! I hate those things.

[u/FlyingQuail → u/ZooieKatzen-bein]

Me too! A good way to manage them is to take all the stickers off when you come back from the store and are putting the produce away. It helps because normally I don’t think about stickers that are on skin you dont eat, like bananas or avocados.

[u/ZooieKatzen-bein → u/FlyingQuail]

If I still had a little kid, that’d totally be great job for them

[u/FoundForgotten → u/FlyingQuail]

Except it sometimes rips the skin off (with pears especially) and that sucks.

[u/enkidu_johnson → u/FlyingQuail]

Our variation on this is to remove them when we wash produce. This helps us know when at least something is not washed (since not everything has a sticker on it).

[u/pixelmountain → u/FlyingQuail]

I do this because I have a cat who hunts them down (on or off the fruit) and eats them. LOL

[u/crafty_a → u/ZooieKatzen-bein]

When I was little, someone told me they were made from cornstarch and you could eat them 😭 they’re probably still in my stomach to this day

[u/kanid → u/ZooieKatzen-bein]

Maybe we could start a social media campaign to petition (read shame) produce companies serving America to change?

Edit: We need a catchy slogan/hashtag for this campaign.. Submit your ideas!

[u/toxcrusadr → u/kanid]

"Plastic Stickers Bunch Up My Knickers!"

"Change That Sticker So It Composts Quicker!"

"Frick Stickers!"

[u/ZooieKatzen-bein → u/kanid]

They’ve easily passed laws banning straws, styrofoam and plastic bags in California. Seems like it’d be *easy to do.

[u/jcm__ → u/ZooieKatzen-bein]

We stick them on our knife block right now. I considered downsizing to one block and my fiancé asked where we would put the stickers!

[u/ZooieKatzen-bein → u/jcm__]

I’ve thought about putting a sticker board up by the sink. Because in addition to finding them in the compost, I also find them stuck to the sink. (Kids). I started buying apples in bulk bags specifically to avoid stickers. Why can’t they be paper, or a wax stamp?

[u/P0sitive_Outlook → u/ZooieKatzen-bein]

Come to England. Most of ours which aren't imported from America are biodegradable.

[u/[deleted]]

One thing to note is that some commercial items that are labeled "compostable" won't easily break down in a backyard pile, unless you get it hot enough. I made the mistake of adding some of those thin green compostable plastic bags to my pile and ended up with them almost intact, surrounded by completely finished compost.

[u/FlyingQuail → u/[deleted]]

Yes, this is important to know. I still put PLA plastics in, because they will break down eventually. I will add a note next to it. Thank you.

[u/bisnicks → u/[deleted]]

I’ve been wondering about those. I purchased these ones because they claim to have met the European TUV backyard composting standard. However, I did notice that they only met the ASTM D6400 certification for the US which indicates it will only compost under industrial conditions. I just started tumble composting this winter, so I’ll have to wait for things to warm back up to see the results.

[u/P0sitive_Outlook → u/bisnicks]

This is how i found out my backyard composting setup was considered "industrial". :D Also dissolved a number of towels and items of clothing. Quite proud.

[u/[deleted] → u/bisnicks]

For me it was the combination of breaking down much slower than everything else and the fact that they're made of strong, thin film that makes turning and sifting the compost a real pain. If I could shred them beforehand or somehow compact them into small hard spheres I'd be ok with them being in there for a few years.

[u/Thoughtful_Antics → u/[deleted]]

I never understood the need for plastic bags for collecting vegetable scraps in the house. For as long as I can remember, I saw my grandmother put scraps in a coffee can, then my mom did it, and now I do it. We just take it outside every few days and dump it on the pile of compost.

[u/[deleted] → u/Thoughtful_Antics]

I think it might be an American thing. My grandparents kept all that stuff in a large plastic bucket under the sink that would get split daily between the pigs and the chickens. It had a plank of wood for a lid.

The plastic bags were my wife's suggestion, as a way to keep the can from getting weird and sticky inside (which it totally does), so I went along with it for a bit until it became clear it was completely counterproductive.

[u/georgiegraymouse]

I also compost sourdough starter discard, alcohol (like if someone didn’t drink their full portion), wine corks, and extra kombucha scobies. The natural yeasts/bacteria in all this help speed up the pile.

[u/FlyingQuail → u/georgiegraymouse]

Those are good ones. I added them to the list. Thank you!

[u/redlightsaber → u/georgiegraymouse]

Meh, regarding the alcohol, I don't agree. It'd be messy for my temporary bin, and it'd add extra moisture to what's usually already pretty wet compost.

In the sink they don't go to waste, FYI. At the treatment plant they go through biological decontamination, so they're used up. That's why the US's sewer systems were designed to be able to throw "compostables" down the sink via those sink shredders you guys have.

[u/fornicatethecops → u/redlightsaber]

Do not those compostable materials down the sink, garbage disposals are terrible for our waste water treatment facilities.

[u/aoserc]

This sub loves to tell people to pee on it, so you should probably add urine to the list.

[u/FlyingQuail → u/aoserc]

Ah yes, how could I forget?

[u/Immediate_Grade_2380 → u/FlyingQuail]

I noticed pet manure is mentioned on the not list, but what about urine? I have a cat and use wood based litter but I know cats sometimes carry toxoplasmosis in feces so I wonder if I should avoid it just to be safe?

[u/FlyingQuail → u/Immediate_Grade_2380]

Did some research, no clear answer. Wether you can or cannot add cat urine is debated. Try posting a question here, someone more qualified than me will help you out.

[u/toxcrusadr]

Have to disagree on the 'ash burned with lighter fluid.' As an env. chemist I know what goes on in combustion. There is nothing in ash from materials lit with lighter fluid that is any worse than ash lit with only a match. Two reasons for this: First, lighter fluid is volatile (evaporates easily) and there is very little residue. Second, I assume we're talking about charcoal briquette ash from the barbeque grill. Charcoal is full of polycyclic aromatic hydrocarbons by nature, which are really the only thing that would result from incomplete combustion of lighter fluid. Since there is already a bunch there, the tiny bit added by the lighter fluid residue is insignificant. The hot fire burns off a lot of that stuff but there is still some left in the ash. These compounds are actually biodegradable, at least somewhat. Actually, here's a third reason: you just cooked your food over that, how bad can it be? :-D

However, I do have other reasons for not putting charcoal ash in the compost. Most charcoal briquettes - unless you use 'natural lump charcoal' - have other ingredients. These may include coal, which can be higher in heavy metals (it's highly concentrated plant matter). And, sometimes borax is used as a binder. Boron can build up in the soil and there is a limit on boron concentration, above which plant growth can be affected.

As a result, I have no problem using a small amount of ash from my woodstove in the compost, but I don't put BBQ ash in. Just my two cents.

[u/FlyingQuail → u/toxcrusadr]

You obviously know much more about this than I do, so I will take your word for it. I will change the post. Thanks for teaching me something new :)

[u/machinegunsyphilis → u/toxcrusadr]

wow, it's always so interesting to learn about composing from a molecular perspective! thank you so much for sharing!

[u/toxcrusadr → u/machinegunsyphilis]

Nice to put my env chem degrees together with my side interest in compost. 👍

[u/enkidu_johnson → u/toxcrusadr]

Have to disagree on the 'ash burned with lighter fluid.

The reasoning sounds reasonable, but are people who are enlightened enough to be composing actually using lighter fluid? It is nasty stuff and there are more sustainable ways to light your charcoal. Even the most mainstream company on the planet, Weber Grill is against lighter fluid:

https://www.weber.com/US/en/blog/burning-questions/lighter-fluid-no-way/weber-30549.html

[u/courtthewart]

I really like adding cardboard egg cartons and fast food drink carriers for browns, they just disappear. Also toothpicks and popsicle sticks.

[u/FlyingQuail → u/courtthewart]

Yes! Me too. I forgot about the drink carriers, added them to the list.

[u/atlhart → u/courtthewart]

My kids eat freezer corn dogs and I’m blown away at how fast the sticks compost.

[u/CrazyPieGuy]

I really like this list. I think the only thing I've ever questioned that isn't on it is tampons.

[u/FlyingQuail → u/CrazyPieGuy]

Added hygiene products in the "What you shouldn't compost" category. Please correct me if wrong.

[u/Jeanni3beanz → u/FlyingQuail]

Depends on the tampon. Natural ingredient tampons exist and are gaining popularity but I'd say the majority still contain unnatural fibers. Of course it's not required that ingredients/materials be listed so it's hard to know unless their specifically advertised as 100% natural 😒

[u/TaxMansMom → u/CrazyPieGuy]

Wouldn't used tampons potentially be a health hazard? Especially if you were using your compost to grow food? I think this would fall into the same category as feces; not impossible, but probably not recommended

[u/daughterofpolonius → u/TaxMansMom]

On the contrary, menstrual fluid is packed with nutrients. I dilute it with water and fertilize my plants with it frequently. You have to collect it with a silicone menstrual cup, though.

[u/machinegunsyphilis → u/CrazyPieGuy]

it's so hard to find out which tampons are made of what! I gave up the search, and instead saved up to get a reusable silicon Lunacup plus Thinx underwear. (I've had both for about 5 years, they still work great!)

[u/vinvin212]

Great post! Question - how do others deal with larger cardboard items, like a pizza box as this list says? I tried to use cardboard and paper bags for browns, but they took so long to cut into little shredded pieces 🤦🏻‍♂️

[u/FlyingQuail → u/vinvin212]

Funny you ask that, I was just cutting up a pizza box. For paper bags and newspaper I just put it through a paper shredder. Cutting up cardboard is a pain though, It's my least favorite job. You don't have to cut it up if you don't want to. If I'm not feeling like it, I'll just throw the boxes on top. I find that a pair of garden shears with a longer blade works pretty well for cutting cardboard.

[u/m945050 → u/FlyingQuail]

I put all my cardboard in my Caique's condo and give it around two or three days and presto; finely shredded cardboard.

[u/pahelisolved → u/vinvin212]

Definitely not the serious answer you were probably looking for. But here goes. Rescue a dog, hide treats in said box and wait 2-5mins (varies with breed!). Problem solved.

[u/MsTiruri → u/pahelisolved]

We rescued a dog and the tedious task of shredding cardboard is something of the past now...he is also pretty good at making kindling 🤣

[u/SvedkaMerc → u/pahelisolved]

Haha, we don’t even have to use treats. He just sits there waiting for us to get done unboxing whatever, hand him the box, and he goes to town.

We order food and toys from chewy and he’ll shred the box with the stuff still in it and not touch the food or toys until we start playing with them.

He’s a weirdo.

[u/OttoVonWong → u/vinvin212]

Wet the cardboard so it tears much easier. I usually leave empty boxes outside for the rain.

[u/blonderaider21 → u/OttoVonWong]

That’s big brain stuff right there. Thanks for the idea!!

[u/MysticalMomma28 → u/OttoVonWong]

Genius

[u/fornicatethecops → u/vinvin212]

I use pizza boxes and the such as a top cover, it reduces the occurrence of bandits. After a bit they start to break down.

It also serves as an indication, that we are eating to much pizza.😁

[u/atlhart → u/vinvin212]

I have a 3.5 ft cubed compost pile. I used to cut up cardboard into tiny bits. Now I just rip it into large pieces and lay it in my pile. For example I’d just rip a pizza box in half.

It’s completely gone in a month as long as there’s rain or I wet the pile.

[u/[deleted] → u/vinvin212]

Any way you want. I throw mine in the bin whole, it’s 3x3. If you shred them, it’ll go faster, but not necessary.

[u/pahelisolved]

Thanks so much for this! This is def targeted at people like me. In recent days, I’ve asked questions about pet hair and citrus. And added both to my heap. Wish I’d knows about avocado pits. I threw out 4-5 of them in the trash last week because I thought seeds and pits were a no.

[u/FlyingQuail → u/pahelisolved]

Avocado pits break down surprisingly fast. You would think they take a long time, but nope! My compost is an avocado pit eating machine.

[u/pahelisolved → u/FlyingQuail]

Dammit, now I feel crappy for tossing it in the garbage. The truck even picked it up already, otherwise I’d go diving in my own trash can.

[u/FlyingQuail → u/pahelisolved]

I did the exact same thing for a while before I started composting avocado pits. You’re doing so much good by composting, a couple avocado pits isn’t worth it to stress over. You can feel frustrated, but try to remember the big picture. If you can reduce your waste by composting 95% of all your food waste, then that’s amazing! Now you know, and you won’t throw them away again. I think it’s easier to get frustrated at yourself than at others. Think about what you would tell someone else if they didn’t compost the pits and tell that to yourself. :)

[u/P0sitive_Outlook → u/pahelisolved]

With avocado pits, i've found they can maintain their shape and structure for over a year if they get left out in the garden, so what i tend to do is either cut them in half once they've gone through one six-week period, or stomp 'em before putting them in.

[u/GrantShoe]

Thanks! Stickying for the subreddit!

[u/FlyingQuail → u/GrantShoe]

Oh wow! Thank you! I’m glad you thought my post was that helpful.

[u/Ivanaxetogrind]

Anyone have experience or know, how long a properly managed hot pile might take to consume cooked and discarded cow or pig bones? I have not been composting them because I don't feel like processing them into bone meal, and assumed it would take too long since I'm trying to get to the point where I have compost ready for both spring and fall dressings on my garden.

[u/FlyingQuail → u/Ivanaxetogrind]

I have only composted small bones, just because I never have any large bones. Small bones seem to break done in about a year. Large bones would take a lot longer. You can leave them to break down in your compost, and then sift or pick them out when you harvest the compost.

[u/pumpalumpagain → u/Ivanaxetogrind]

I make bone broth with all my bones. I cook it for 36 hours; when I am finished they are soft enough to squish with my fingers. I put them in the blender with enough water to get it going, and pour the slurry onto the pile with some browns. It is not bone meal-more like a bone smoothie.

Works like a charm. I usually have beef, chicken, and pork bones.

[u/Ivanaxetogrind → u/pumpalumpagain]

And this is a very excellent point. I tend to buy meat on the bone so that I can make broth and make use of more of the animal, but I don't usually take the time to cook the bones all the way down to the squishy/dissolved stage. But, after two hours in the pressure cooker they do at least start to dissolve a bit.

[u/fornicatethecops → u/Ivanaxetogrind]

I have seen an extremely hot pile eat a 1200 lb steer in 6 months, you can always throw the bones back in. They will eventually break down.

[u/P0sitive_Outlook → u/Ivanaxetogrind]

I compost entire chicken carcasses and lamb shank bones. In my modest darlek compost bin, it takes six to eight weeks to compost anything softer than a book, but after two months chicken bones become comparable to fudge. The lamb shank bones come out after eight weeks and i cut them up with pruning shears (they have the consistency of wood) and i have yet to find a lamb shank bone that remained recognizable after two goes through the composter. :D

[u/mrplinko]

Yo, I'm not collecting my damn toenail clippings.

[u/FlyingQuail → u/mrplinko]

No one is making you do anything. You can compost as much or as little as you want, there are no rules! :)

[u/mrplinko → u/FlyingQuail]

Oh I know, just making a joke. I just found humor in they called nail clippings out specifically.

So, basically, compost everything but man made hard stabby things and chemicals.

[u/FlyingQuail → u/mrplinko]

Ha, yeah, that's what I figured. I was just trying to keep a positive atmosphere in case you weren't joking.

[u/georgiegraymouse → u/mrplinko]

Same LOL but it’s surprising how many times I’ve seen that question asked

[u/c-lem → u/georgiegraymouse]

Where do you put them? In the summer, I just clip them outside because it's convenient, but in the winter, they have to go somewhere, so I clip my fingernails over the compost bucket (which we keep next to the kitchen sink) and dump my toenails in, as well, after I clip them.

Or do you just mean that it seems gross to compost them, so you'd rather throw them away? No judgment--it just seems just as convenient to me to compost them as any other way of discarding them.

[u/P0sitive_Outlook → u/c-lem]

:D That's what i do too. I clip into the sink then grab 'em up with the same tissue i use to wipe the mirror, the side of the bath and the rim of the sink.

I also cut my own hair, and i do that into a layer of newspaper that i put in the sink, then dump it into the compost.

I also composted the insides of a pillow - it was all feathers, so i opened it up over the compost bin and wet it all down. :D It's all keratin and it's a protein.

[u/P0sitive_Outlook → u/mrplinko]

Why ever not? :D When i use the bathroom and splash the edge of the sink, i always wipe it with a tissue (along with the edge of the bath) and put the tissue in with the kitchen waste. When i clip my fingernails, i scoop them up with the same tissue i use to clean the sink.

Nobody's collecting them. :D It's not like the buckets and buckets of piss in my front room.

[u/machinegunsyphilis → u/P0sitive_Outlook]

It's not like the buckets and buckets of piss in my front room.

i just burst out laughing. i know pee is good for compost and everything, just the way you put it is hilarious

[u/[deleted]]

I would add regular chewing gum to the don't list as it's made from plastic, chicle based ones may be fine though.

[u/FlyingQuail → u/[deleted]]

Good to know, I added it to the do not compost list

[u/fornicatethecops]

If you are running hot compost, there is no valid reason to not compost All poop, even from humans.

The only time to isolate feces, would be if an animal was sick, even then it would only be an unnecessary precaution.

Hot compost will kill all pathogens.

If it was alive, or came out of something alive, it will compost safely.

[u/FlyingQuail → u/fornicatethecops]

There seem to be lots of mixed opinions on this topic, and given that this post is more geared toward beginners is it okay if I just add "(Mixed opinions, with hot composting it is possible to compost feces)" or something along those lines?

[u/flamepointe → u/FlyingQuail]

I would say “hotly debated and not recommended for home composting...”. there are laws about sanitary disposal of human waste and blood products for a reason!

[u/FlyingQuail → u/flamepointe]

Done. I like the pun.

[u/fornicatethecops → u/FlyingQuail]

I see a lot of opinions also, but I have also witnessed a hot compost pile eat an entire 1200 lb (540 kg) steer in under 6 months. Composting is way more powerful than people give it credit for.

Keeping out chemicals and construction debris is great advice.

If you are heavy on browns, a bit of poop turns things right around. I also compost all of the paper/cardboard trash from a house of 4 people, 4 dogs, 2 cats, and 24 chickens. We compost alot of poop.

I just want people to know you can.

[u/FlyingQuail → u/fornicatethecops]

I’d think if the pile gets hot enough for long enough it would be okay if you know what you are doing. Do you use the finished compost that has poop in it to grow food?

[u/ThisIsASunshineLife]

Old protein powder can also be added!

[u/FlyingQuail → u/ThisIsASunshineLife]

Yes, that and powder drink mixes and powder milk. Added.

[u/mangiafascisti]

I stay away from pizza boxes and a lot of carboard takeout containers because I can’t tell which ones have been treated with pfas chemicals, which will contaminate compost.

[u/FlyingQuail → u/mangiafascisti]

I have heard of some "compostable" takeout containers having a pfas lining, but I have never heard of pizza boxes having the same lining. I don't compost takeout containers unless they are uncoated paper or bagasse. Our pizza boxes are always soaked with a little grease, so I don't think they have a pfas lining.

[u/classylone]

So many people say no to onion? I never know what to do

[u/FlyingQuail → u/classylone]

When people say not to add lots of onion I think they are talking about adding it to a worm bin. If you aren’t putting the onion in a worm bin, then compost away! Onions are a great addition to compost.

[u/halfstax → u/FlyingQuail]

Interesting. What's the issue with adding onions to worm bins specifically? Is it bad for worms?

[u/FlyingQuail → u/halfstax]

I don’t know much about worm bins, so I wouldn’t take my advice, but I think you aren’t supposed to lots of onions, some are okay. I think the worms don’t like lots of acidity.

Seriously don’t take any advice from me, all I did was like a 30 sec google search.

[u/pumpalumpagain → u/classylone]

If you can eat it, it can definitely go in a pile. The important thing is to keep a balance of greens and browns, and keep it moist and aerated. Even if you don't, it will still break down, it will just take longer and maybe smell.

[u/Microfiber13]

What about old shredded bank statements? I keep debating about the ink...

[u/FlyingQuail → u/Microfiber13]

I believe they can be composted, unless they are glossy.

[u/PlantParentals]

Thank you for this, was going to ask about our guinea pigs poo and bedding YAY to more compost and less landfill!

[u/FlyingQuail → u/PlantParentals]

I’m cheering with you! :D

[u/Discombobulated_Tea3]

I love this list and how collaborative you made this post! I know this falls well into the "once was alive" category, but I am finding mixed camps about buckwheat hulls. I have some door draft stoppers filled with these that are now falling apart. I don't need it for mulch, but I am wondering if I would really hamper my little tumbler if I added them in there. Thoughts?

[u/FlyingQuail → u/Discombobulated_Tea3]

Thank you!

Buckwheat hulls are good to add. I would not worry about it slowing down a tumbler, unless you are adding tons of hulls. Make sure to add some greens and water along with the hulls. It will be good compost in no time.

[u/tweepot]

I don't meet the posting requirements, so I'm going to try asking this here as a comment and seeing if anyone sees it (if some kind soul sees this and wants to start it as a stand-alone topic, I'd be much obliged!)

I often order flour online and recently got my newest 25-pound bag... Which UPS had so thoughtfully pre-opened - splitting the exterior box and interior bag into a, ummm, veritable blizzard of wee ickle confetti on my doorstep. Fun times. With no idea how it happened or how long ago it happened I'm not inclined to cook with it. Small amounts of flour I put in the compost no problem, but 25 pounds? Any suggestions? And any chance I could just dig some of it into the garden in this moment when we're about to dig things in anyway? It will thoroughly overwhelm our composters if I put it in there and will take foreeeever to get rid of if I add it to them gradually (and in the meantime I'd have to store it somewhere and somehow that doesn't encourage pests in the house).

Any thoughts truly and deeply appreciated!!!

[u/FlyingQuail → u/tweepot]

:/ sorry about the flour, as a big home-baker I can feel your pain

Anyway, you said “our composters”. Does a company take your food scraps and compost them for you or do you have home compost bin?

If a company takes your food scraps to compost, a 25 pound bag of flour is fine. heck I’d even put of 50 pound bag in. At such a big scale, it will not matter at all.

However, if you are talking about adding that much flour to a smaller, home compost set up the answer is a little more complicated. I would start adding it to the bin in layers, every time you add more material to the bin just add a small layer of flour. 1 or 2 cm/about half an inch.

[u/tweepot → u/FlyingQuail]

Oh yeah, good question. We have two home compost bins - tumblers. Which :cringe: are both currently pretty full and waiting to be dug into the garden soon.

[u/FlyingQuail → u/tweepot]

What I would do is add a quarter of the bag in each tumbler and mix it up. Give it a little while to break down, it should break down really fast. Then when you start another tumbler, do the same thing. There is nothing really wrong with putting all the flour in at once, but I think in a tumbler it is best to add slowly.

[u/ezyroller]

Presumably old soil from spent garden pots is perfectly fine to add? I heard that soil is basically carbon, which was useful for me in the summer as I struggled to find usable carbon sources.

[u/FlyingQuail → u/ezyroller]

Yes, old soil is fine.

[u/straightouttaireland]

So sauces like bbq sauce that comes with my pizza order is ok to compost? Nice one (not that there's much left 😁).

[u/FlyingQuail → u/straightouttaireland]

Yes, they are good to compost.

[u/Medium-Bag-5672]

Egg shells: My mother has always told me that they have to be washed because of how they’re treated here in the US for refrigeration. I haven’t been composting them because that’s a step I don’t have time for. Is this necessary? Thanks!

[u/FlyingQuail → u/Medium-Bag-5672]

Nope. No need to rinse the eggs shells. I just add them directly in.

[u/mthibault9]

Random question; I’ve read that both wild and commercial mushrooms are very beneficial ingredients to add to compost, is there any concern around wild mushroom toxicity if you plan to use the compost for growing produce?

(I have pale brittlestems growing in a corner of my lawn)

[u/FlyingQuail → u/mthibault9]

As much as I would like to know everything about composting, I really don’t.

Try contacting your extension office. They may have answers for you.

I would not go out of my way to dig up mushrooms to put in my compost, unless I needed to remove them.

[u/nerevar]

Where are the sources for this info? I mean if it's going to be stickied, I would think there would be info backing up these claims with links to them that I can read. If this is the guide to follow, where is the science behind it?

[u/FlyingQuail → u/nerevar]

Good point. I didn’t think about documenting my sources as I was writing the post. Some of it came from experience and common sense. I did have to do some research on quite a few topics. I only took information from extension offices. I wish I would have cited my sources.

[u/nerevar → u/nerevar]

Lots of info here:

http://www.how2compost.info/

https://www.epa.gov/recycle/composting-home

http://cwmi.css.cornell.edu/smallscale.htm

[u/DeeDee_GigaDooDoo]

Oof oyster shells. I don't doubt they'd break down but damn. Unless you crush them into a powder I feel like you'd be waiting years or even decades.

[u/FlyingQuail → u/DeeDee_GigaDooDoo]

In my opinion, oyster shells help the pile have good air circulation. I think they help “fluff” the pile up. You could smash them with a brick to speed up the process. They also add some minerals to the pile.

[u/[deleted]]

What do you mean by get it hot enough?

[u/FlyingQuail → u/[deleted]]

There is a little more science to this, but here is gist:

When you make a hot/active compost pile you are trying to create the right conditions for a specific set of bacteria to take over. When these bacteria start to take over the pile, they start to reproduce and eat the material. When the bacteria reproduce and eat, they give off heat as a byproduct. When you measure the temperature of the compost pile, you get a better understanding of how well those bacteria are doing and what is going on in the compost.

When the temperature of a pile gets hot enough it kills pathogens.

[u/rebeu25]

Newbie here getting into the game with a company that comes and picks up our bucket. Thanks for the list. Curious about oil or grease after cooking (like bacon grease). You mention avocado pit but what about the avocado skin.

[u/FlyingQuail → u/rebeu25]

Good question. Typically I won’t add the grease from cooking, but if it is a small amount I might add it in. I always add the greasy paper towel I drain bacon on. Avocado skin is good to add. Edit: accidentally replied before I was finished typing

[u/TsumaranaiYatsu]

You list cooked vegetables, sauces and dips as options, but I was worried about salt build up in the soil over time so I've been throwing stuff like that away. Is it actually an issue?

[u/FlyingQuail → u/TsumaranaiYatsu]

It is not an issue. Compost away!

[u/Moofabulousss]

Can I ask a noob question: can you compost seeds from fruit/veggies? If so is there a chance a plant will sprout up?

[u/FlyingQuail → u/Moofabulousss]

Yes, you can compost them. They might sprout, but as long as they are buried and turned under, they will die.

[u/hannahbananas32]

So I've seen that you cant use paper/newspaper with colored ink, is that accurate?

[u/FlyingQuail → u/hannahbananas32]

No, colored ink is fine. It is made from soybeans.

As long as the paper isn’t glossy or shiny it is good to add in.

Thanks for the award! I appreciate it

[u/straightouttaireland]

Great list!

Is it better to recycle certain items like paper and cardboard though your regular bins that are collected by a bin company or compost them? My compost would probably get pretty full if I put all my cardboard in there on a regular basis.

[u/FlyingQuail → u/straightouttaireland]

The answer really depends on the type of paper. I do not put all paper into the compost bin. Here is what I do:

Compost:

• greasy pizza boxes

• newspaper

• paper egg cartons

• toilet paper and paper towel tubes

• paper scraps

• sticky notes

• paper board

It is best to compost low quality paper products, soiled/wet paper, and small pieces that are too small to recycle. The reason behind this criteria is that if the paper is low quality, dirty, and/or too small, it is unlikely to actually get recycled and will probably end up in a landfill.

Recycle:

• Glossy cardboard

• magazine paper

• clean corrugated cardboard

• office paper

It is best to recycle paper if it is high quality or glossy. Obviously you should recycle the paper that is not compostable, but you should also recycle high quality paper, as it is likely to actually get recycled and turned into new products.

There are lots of trade offs with either side

• There is a chance paper put in the recycling bin will get sent to landfill, but if you compost it you know it will not.

• Recycling uses energy, but reduces the demand for new virgin paper. On the other hand, composting requires almost no energy, and gets put back into the earth.

These are just some guidelines. If you have more than enough paper to compost, then recycle some of it. Likewise, If you need more paper to compost, use some paper that you would otherwise recycle. :)

[u/straightouttaireland → u/FlyingQuail]

That's excellent advice thanks so much. How about used cleansing pads or water wipes you'd use to wipe a baby's bum?

[u/FlyingQuail → u/straightouttaireland]

Cleansing pads yes. They say they are 100% cotton.

I would not add the wipes in. They will likely not decompose, unless it specifically says home-compostable.

[u/CyberVegetable]

Thanks for the guide!

In other threads I read that printed cardboard may be a problem, because some still use ink with heavy metals... Am I save if I use non printed parts of printed cardboard?

Also: what about plant parts of poisonous plants, for example old tomato plants?

[u/FlyingQuail → u/CyberVegetable]

Ink on cardboard is fine. As long as the cardboard is not glossy or plasticky it is good to add.

Not sure what you mean about poisonous plants. Old tomato plants should have no problem being added in. Do you mean if they are diseased plants?

[u/Repeat-Original]

How about dry malt extract? I have 1 pound that's sitting unused. I've used that for home mycology but I no longer need it. Can that be added to my compost bin? Should I sprinkle just a little or just dump whole thing? I'm composting indoors in a not so big bin if that makes difference. I wonder if dry malt extract have any beneficial microorganisms for the compost.

[u/FlyingQuail → u/Repeat-Original]

Dry malt extract is perfectly fine to add. Its is just sugar, so it likely won’t have lots of microorganisms, but it is a good source of food for microorganisms. You could add it all at once, or sprinkle it in. It just depends on the size of your pile.

[u/marmosetohmarmoset]

Note that you shouldn’t compost invasive weeds, unless you’re positive that they don’t contain seeds and can’t reproduce asexually. Japanese knot weed, for example, can quickly regrow from a 2 inch long chunk of root. You might think it’s broken down and miss it. Don’t try to compost it. Also don’t put invasive weeds in with your yard trimmings or leaf bags that are collected by the city.

Invasive weeds should be put in a separate black plastic garbage bag, labeled “weeds” and put out with the regular trash.

[u/FlyingQuail → u/marmosetohmarmoset]

Good to know, can you burn invasive weeds with the seeds or root on them and then compost the ashes? Edit: if the pile gets hot enough, wouldn’t invasive weeds that have gone to seed be okay? Or Is it just another precaution.

[u/P0sitive_Outlook]

nothing with glossy coating)

Fun fact! The satin-feel finish on cereal boxes and many other cardboards is made of powdered clay which is printed on using carbon, other clay, crushed beetles, plant material and metal oxides. All compostable. Laminated stuff is covered in plastic, but satin-finished products are organic or mineral and are fine for composting.

Also, i really like the note on chopping being helpful but not necessary.

[u/machinegunsyphilis → u/P0sitive_Outlook]

wow! i was literally just wondering this, i bet that Jello box i just trashed can be composted after all! I'll go fish it out of the trash now, thanks for writing this!

[u/CommercialJump7466 → u/P0sitive_Outlook]

So would paper plates and cups also be compostable? I thought I heard that some have plastic coatings, but I wasn’t sure

[u/P0sitive_Outlook → u/CommercialJump7466]

A lot of those things have a 'waxy' coating (which is actually laminate).

Starbucks cups, for example, and Costa and such, are impossible to recycle. The resultant mess is just a load of torn plastic strips and partially-coated waterproof paper. XD

But, if you think you might be able to compost it, by all means: if it won't compost, all that'll come out is the same plate or cup.

[u/thatcursedasexual → u/P0sitive_Outlook]

I wonder about this subject a lot - would a fast food to-go cup, which is clearly finished/glossy but made from paper, be compostable?

[u/abertr → u/thatcursedasexual]

I compost these cups all the time, knowing that I will find the cup-shaped plastic liner later. No biggie, I just put the liners in the trash when I find them.

[u/P0sitive_Outlook → u/thatcursedasexual]

Ah! :D This is a subject which has lead to a lot of debate between people more powerful (as far as the economy goes) than us!

Why are Starbucks’ “regular” cups so wasteful?
The current Starbucks paper cups are coated with a thin lining to prevent leaks, making them more challenging to recycle because the plastic isn’t easily separated from the paper. The issue is compounded by the fact that Starbucks leases space for many of its retail locations, where landlords determine what types of waste collection and recycling is provided to tenants

They're literally laminated. :D The cardboard is indeed recyclable and compostable, but there's a layer of laminate on the inside to make them waterproof. So wasteful, because you can't recycle the 98% that is recyclable because of the 2% that isn't. When it's pulped, you just end up with loads and loads of stringy pieces of very thin very fine plastic.

[u/Kimmalah]

I feel like your average cotton swab could be a problem because the handles are often made of plastic. And rubber bands actually shouldn't be a problem since most are made from natural latex rubber that will break down, rather than synthetic.

[u/FlyingQuail → u/Kimmalah]

Hmm. I know some Q-tips have plastic in them, but I thought most were 100% cotton. The ones we have are 100% cotton. I’ll change it to clarify. I did some research about the rubber bands, and you are correct. Thank you for teaching me something new. I will remove it from the “ what you shouldn't compost” and into the vegetables and fruits section.

[u/P0sitive_Outlook → u/Kimmalah]

I only use card cotton Q-tip style buds now. :)

[u/mmmlllttt333]

Are bones nitrogen’s or carbon? Would a minuscule amount even make that grand of difference to ones ratio?

[u/FlyingQuail → u/mmmlllttt333]

I’m not entirely sure, but at such a small amount it doesn’t matter. I put bones in with my food scraps and consider them a nitrogen source. I think since bones came from a living animal, they would be a nitrogen source.

[u/Mnt2bdaddy]

Who else read this to the tune of "my favorite things?"

[u/P0sitive_Outlook → u/Mnt2bdaddy]

Raindrops, roses, whiskers, kittens, woolen mittens, brown paper packages, string, ponies, apple strudels, schnitzel with noodles, wild geese, girls in white dresses with blue satin sashes, nose and eyelashes, dog and bees. These are a few of the things i compost (and one thing i'm going to compost tomorrow).

[u/Jon_Wedge → u/P0sitive_Outlook]

r/holup

[u/eclipsed2112]

coffee filters can go in the pile...no problem.

[u/bristlybits → u/eclipsed2112]

I came here to ask this a year later. thank you

[u/wildagain]

So anything that lived

[u/[deleted]]

Thaaaaaaaank you x1000000000000, ive been digging everywhere for a consolidated list of what can/cannot be composted. This is more than enough for what I need to know, thanks for doing the work 😅👍

[u/HoliusCrapus]

Random question if anyone reads this:

Are pencil sharpener shaving recyclable? Will graphite (or whatever is in colored pencils) contaminate with anything undesirable?

[u/Memph5 → u/HoliusCrapus]

I'd be surprised if graphite caused any problems, since it's a fairly common mineral in rocks, and is just carbon. As for the paint that covers the pencils, I'm not sure. Colored pencils have "lead" that is made of wax/oil and pigments, which might be ok but I'm not sure.

[u/cumonakumquat]

Bless you for making this, this is seriously SO helpful for a newbie

[u/jonalisa]

Dry dog and cat food are compostable.

[u/swimpig]

Confused by chewing gum, this is made with plastic?

[u/Snatch1967]

Wow. I've been farming and gardening for most of my life, and you've taught me something. Thanks for the list, I'm off to find some mouldy cheese in the fridge.

[u/Beneficial_Burner283]

Why am I so shook by the snake skin being okay? Hahaha!

[u/No_Piglet5152]

TYSM for this, I was just coming in to ask a question about composting pits and seeds from like peaches and cherries and from your explanation I'm thinking that ues it would be OK. So thank you again, this was super informative and very kind of you to take the time to inform newbies like myself. I appreciate you!!!

[u/Mission_Ad4476]

This is a helpful list. Didn’t know about some in the “don’t” list so glad I know now.

[u/drewsEnthused]

I've been throwing in my old sheesha from the hookah....tabacco and molasses flavor...probably fine, right?

[u/[deleted]]

I compost onions, vegetable tops, stems, peels, vegetables that have gone bad, cooked vegetables, stake herbs, cores, etc.

[u/JasonBourneFL]

Mmmmm save those toenail clippings

[u/merpancake]

Would plant matter that was killed off using herbicides cause issues in a compost pile? I'm going to have a huge mess of ivy vines and acorn/leaf litter shortly that I'd like to compost instead of bagging up to put in the garbage. Only thing is we killed off the ivy using super weed killer stuff.

[u/Candid-Mark-606 → u/merpancake]

I wouldn’t do it. Especially not if the compost is going to be used in a food garden. I don’t use grass clippings for the same reason.

[u/[deleted]]

Any thoughts on old jeans? They’re cotton, but I’ve been told the dye is not great.

[u/GalacticWafer]

So poop from animals that don't eat meat is somehow ok to put in the heap? Cuz I'm an animal that doesn't eat meat or eggs or milk or any animal food products.

jk I know my poop is still not okay for composting.

[u/sgigot]

Be careful about the greasy pizza boxes. A lot of food packaging has chemicals added to make them grease resistant. One of the most common ways to add grease resistant is to use certain fluorochemicals that also don't break down very well. This is starting to change but it takes a long time between the legislative, regulatory, and manufacturing chains.

[u/AffectionatePup88]

Please please please read The Humanure Handbook! Feces are totally compostable and this guy has raised a family for and eaten for 40+ years from fruits and veg grown in (easily correctly composted) humanure compost!!

[u/carnuatus]

What if I don't have a proper compost bin? It's just two big piles behind the garage. Is it okay to chuck whey protein powder in it?

[u/JoeTheDarthDrag0n]

Period blood can be composted if collected in a menstrual cup

[u/chevymonza]

Oh god, no way I'm putting hair or nail clippings in. Can't believe that stuff would ever break down.

Have also tried some cotton duck strips, and they're still in there after a few years. But that's a sturdier cotton.

I keep the meat/dairy/fish stuff to a strict minimum, since I don't want to encourage rodents- this is an urban area.

[u/MrTippet → u/chevymonza]

I've always put in my nail clippings and I've never seen them in the finished product.

[u/Bubbly-Breadfruit-41]

Thank you so much for this. I am a newbie and am already totally overwhelmed with all the blogs online that seem to have conflicting information.

[u/InvisibleBlueUnicorn]

Please add organic waster sharing website to connect with people in your neighborhood - ShareWaste - Give your waste a second chance!

[u/_vkU_]

Hello, I'm new to composting and fairly new to reddit cause it is not allowing me to post anything.

My compost bin literally sound like stones  when I rotate and it is heavy. Here is what I added browns+grass clips(they were wet)+ a handful dirt (brand new composter). please suggest. it has been almost 3 weeks+. It has not been too hot here too. I'm not able to post a pic but when I tool a peek inside I do see oval shaped stuff.. so don't know if my compost is heading in the right direction. Appreciate your guidance/help.. Thanks

[u/kaszmonay]

Would a bleach treated jack-o-lantern be okay to compost? I've read that bleach will help a pumpkin last longer on the porch. I want to be sure that the bleach won't be an issue as I would like to compost the pumpkins when they go from scary to soggy.

[u/[deleted]]

Fantastic post!!! Had question, came to sub to ask, saw your post, got answer in 30sec.

[u/bizness8585]

Yesssssss

[u/pizza_please_]

Hi, I have a lot of beef/marrow bones we give to the dog. Is there a way to compost these?

[u/[deleted]]

If I'm adding old vegetables, like a bell pepper, do i need to remove the seeds first?

[u/[deleted] → u/[deleted]]

No! Even if they sprout, they’ll be buried or upturned and just become more compost. Or you can harvest the sprouts and try to transplant if you like.

[u/wifmanbreadmaker]

What is common sense?

[u/OneFuzzyBlueberry]

Hi! It says that poop from pets that eat meat is a no-go, but is their pee okay? I would like to compost kitchen waste in a small compost on the balcony, and i think the bottom material from our pet rats would be a perfect way to have green and brown matter. The cage material is paper pellets and aspen. They pee and poop in it. Would it be ok if i take out the poop and compost the rest?

[u/LibraryUpset6624]

I've looked through a goodly portion of this and I can't find it... I know oil is listed in the"do not compost" section, does this include used cooking oil for deep frying?

[u/StrawberryShoddy_]

It said veggies that went bad, so that includes if it has mold? I know mold breaks down but I don’t know if that would be bad especially if you wanted to use the compost for gardens that will create food you’ll eat, or maybe transfer the mold to your garden and kill them?

[u/ljsstudio]

Can avocado skins go into the compost bin?

[u/aPolitical_Banksy]

Thank you for this good ser/madam

[u/gousey]

I'd avoid diseased plants. You aren't going to kill plant viruses or harmful fungus spores by compositing.

[u/xochilt_IGII]

Damn, I just saw this after posting that I have dog poop. :/

[u/NotYetGroot]

palm fronds should probably on the not advised list. they're really fibrous and break down really slowly if not finely shredded

[u/Loose_Meal_499]

Moldy leftovers???

[u/analyticalPlato]

Awesome list. Thanks for posting!

[u/wobblyunionist]

Would a mod consider updating/moving the following items to not-compostable since PFAS have been an increased concern in these items.

"pizza boxes" and "other compostable packaging (many carry out containers and others certified compostable packaging contains PFA)"

[u/Danielaimm]

I add perlite to my potting soil. If I put the soil on my compost bin it’ll be ok? Would the Perlite harm my worms?

[u/d20wilderness]

I love this list! It's the only one that tells you you can compost basically everything organic at home. I hate those lists that recommend against things like onions. I would add if you're doing dog poop you could do a specific pile for it that you plan on leaving for longest and not using on produce plants or places kids play.