What You CAN and CANNOT Put In A Compost Bin

What You CAN and CANNOT Put In A Compost Bin?

Firstly, before we go into this topic, I’d like to congratulate you on making the decision to compost your waste. You are an earth-saver for choosing to do this. Converting waste to compost for manuring our garden keeps this waste out of the landfills and incinerators, thereby reducing the amount of harm we are causing the earth. Domestic waste constitutes about 30% of the solid waste being dumped in the U.S landfills, according to the Environmental Protection Agency. If everyone (not just gardeners) could compost most of their domestic waste, we can reduce this percentage by a lot and enrich the soil for cultivation. If you have no use for the compost, it’s actually a good market. You can sell it to your neighbors or friends.

Compost bins are structures or containers used to make compost and house them until they are fully decomposed and ready for the garden. They facilitate the decomposing process through adequate aeration (usually open-bottomed) and moisture retention. With compost bins, you don’t have to dump and shovel your compost in the backyard anymore. The smell could raise the dead back to life, and let’s not get started on the rodents.

Deciding what to put in a compost bin can be confusing at times. Your compost might take longer to decompose or attract all the critters in the neighborhood if you’ve been putting in the wrong stuff. Different composting techniques are suitable for specific kinds of materials.

You could also use a compost tumbler, which is a closed stricture that enables you to mix or tumble your compost very efficiently. The closed-off nature of this structure permits the addition of odoriferous kitchen waste, such as eggs, fish, meat, etc.  On the other hand, adding these materials to a compost bin would turn the process into a pest and stench nightmare.


So, what CAN you put in a compost bin?

There are two major classes of materials that can be added to the compost bin:

  1. Green (wet materials)
  2. Brown (dry materials)

Green materials are the fully organic materials that contain enormous amounts of nitrogen, which speeds up the decomposition process. These include food items and animal feces (excluding dog and cat poop). They usually contain moisture and will provide enough nitrogen for decomposing the rest of the materials.

Brown materials are dry or processed organic matter, such as dry leaves, paper, cardboard, wood splinters, straw or hay, etc. These materials are high in carbon content and will take a longer time to decompose.

Getting the right balance of green and brown materials is important for the proper decomposition of any compost mixture. Brown materials usually add to the bulk of the compost while the green materials speed up the overall decomposition of the materials in the mix.

Green kitchen materials that CAN be added to the compost bin include:

  • Tea leaves
  • Coffee powder
  • Fruit and vegetable waste
  • Spoiled rice
  • Decayed nuts and soybeans
  • Spoiled tomato paste
  • Tofu, tempeh, seaweed
  • Moldy cheese
  • Corn seeds and cobs
  • Piths from avocados, mangos, peaches, and plums
  • Wine, beer
  • Seeds
  • Herbs and spices
  • Jelly, jam,
  • Dry pet food
  • Yam peels

Green kitchen materials you CANNOT add to your compost bin include:

  • Meat
  • Fish
  • Dairy products
  • Bones
  • Leftover meals
  • Onion and citrus peels

These materials (excluding the onion and citrus peels) decompose far too quickly and would release an excess of gaseous compounds that would cause your compost bin to overheat, turning it into a messy, stinky mush. The decomposition process would basically be messed up. They also produce strong odors that would not only be disturbing to you, but also to your neighbors, and that’s totally unfair. People have had to move away from their homes due to the awful smell emanating from badly prepared compost.

They’ll also attract pests, rodents, and critters to your compost bin. If you live in a bear/coyote prone area, get ready for some esteemed visitors too. Rats would become an epidemic in your home.

Despite the fact that fruits and vegetables are wonderful additions to the compost, citrus and onion peels are highly acidic and would destroy the micro-organisms effecting decomposition in your compost. These materials would only prolong the process.

Brown kitchen materials that CAN be added to the compost bin include:

  • Pretzels
  • Biodegradable tea and coffee bags
  • Biodegradable coffee cups that do not contain any plastic
  • Protein bars
  • Cereal waste
  • Eggshells
  • Paper bags
  • Paper towels/napkins/serviettes
  • Oatmeal
  • Paper muffin cups
  • Cardboard cartons
  • Toothpicks and stalks
  • Nutshells (do not add walnut shells. they release a compound known as juglone that impedes the growth of plants. They are generally safe for humans and animals, except horses).
  • Bamboo kebab sticks
  • Any paper material that you are certain is biodegradable.
  • Wine corks

Brown kitchen materials that CANNOT be added to the compost bin include:

  • Colored paper
  • Glossy paper or inked paper (such as magazines)
  • Non-biodegradable coffee and tea bags
  • Labels on fruits and vegetables
  • Nylon materials
  • Glass bottles, jars, containers
  • Anything that contains plastic
  • Coal ash
  • Varnished wood

These materials do not decompose easily due to their high carbon content. Glass would take thousands of years to decompose. Some of the brown materials contain inorganic chemicals that can be harmful to the soil when used in compost.

The ink from colored paper is a toxic chemical and should be avoided at all cost. If you’re not certain of the biodegradability of your coffee and tea bags, do not add them to your compost.

Coal fire ash contains high amounts of sulfur and its compounds that will not only kill the micro-organisms in your compost but also impede the growth of your plants when added to the soil.

Varnished wood and sawdust from treated wooden materials contain toxic chemicals that destroy the natural nutrients in the soil and can be harmful to micro-organisms. Natural and untreated wooden materials and splinters may be used for compost, but when they contain any treatments or enhancements, they should not be added to compost.

Green household materials that CAN be added to compost:

  • Grass clippings
  • Leaves from the surroundings
  • Pumpkin lanterns (be sure to crush or smash them)
  • Rabbit, poultry, or hamster droppings
  • Horse, goat, cow feces
  • Dead house plants and flowers

Green household materials that CANNOT be added to compost:

  • Diseased plants
  • Dog or cat droppings

Diseased plants should not be added to compost because the micro-organisms in them would spread throughout the rest of the materials. Diseased compost would, in turn, infect the plants to which it is applied. Dead plants can be added to compost, but if a dead plant has suffered any microbial disease (a rot, blast, blight, and wilt), it should be excluded from the mix.

Feces from most other animals are safe for compost and usually add a wealth of nutrients to the soil. Dog or cat droppings, however, contain disease-causing micro-organisms that can affect plants and cause harm to humans.

Brown household materials that CAN be added to compost:

  • Tissues or paper rolls
  • Non-plastic cotton swabs
  • 100% cotton materials from the laundry room
  • 100% natural linen
  • Shredded envelopes (remove the plastic window)
  • Pencil shavings
  • 100% natural wool materials
  • Christmas trees
  • Natural garlands
  • Mistletoe
  • Feathers
  • Straw or hay
  • Alfalfa
  • Fur
  • Pinecones
  • Wood chips

Brown household materials that CANNOT be composted:

  • Synthetic materials
  • Coal fire ash
  • Glass
  • Aluminum
  • Tin
  • Nickel, bronze, and copper materials
  • plastic

These materials are non-biodegradable and they contain tons of toxic compounds (mostly of carbon) that will not impede the growth of plants but also harm humans upon consumption.

Getting your compost right

Getting the right compost mixture isn’t merely about the perfect balance of green and brown materials, although this is crucial to the process. There are other factors to be considered before the compost bin will be ready to sit and decompose.

Effectively reducing the surface area of the materials

Do not throw whole materials into the compost bins. They will take longer to decompose when their surface areas are large. Micro-organisms break down small-sized materials faster. Chop up all your waste materials, especially the brown or dry ones. Crush piths and seeds before composting them. Tear papers into tiny shreds and smash the nut shells to crumbles. You’ll have your compost ready in a shorter amount of time.

Aerate and moisten

Oxygen is important for decomposition. An air-tight compost bin would take longer to decompose, and the process won’t turn out quite right. Turn your compost regularly to aerate it. Doing this will also even out the spread of nitrogen and micro-organisms. You can use a pitchfork or a shovel for this task, or you could just get a compost tumbler straight up. Either way, it has to be mixed and turned for air penetration.

A dry compost pile would also take longer to decompose. Micro-organisms thrive better in moist environments, and they need water to survive and reproduce. If your compost looks dry and scrunchy, add some cups of water to it or hose it down. Addition of water means the compost would have to be turned more frequently, though. Water takes up the space for air molecules and you don’t want the micro-organisms to lack oxygen.

In a nutshell…

Making compost isn’t a Herculean task. All you have to do is make sure that no non-biodegradable material is included in your mix. Do not use strongly odoriferous kitchen waste, diseased plant and animal parts, and most importantly, resist the temptation to use your dog’s or cat’s droppings in your compost.

Happy gardening!


  1. Composting At Home. Environmental Protection Agency. Retrieved from https://www.epa.gov/recycle/composting-home.
  2. Open-bottomed compost bins facts to know. Do It Yourself. https://www.doityourself.com/stry/open-bottomed-compost-bin-facts-to-know
  3. Compost tumblers. Earth Easy. https://learn.eartheasy.com/guides/compost-tumblers/.
  4. 10 Things You Should Not Put In Your Compost Pile. Small Foot Print Family.https://www.smallfootprintfamily.com/garden
  5. Toxic Plant Profile: Black Walnut. University of Maryland Extension. https://extension.umd.edu/learn/toxic-plant-profile-black-walnut