Indoor composting is not for the faint of heart. Casual composters can throw a pile of leaves in the corner of the lawn and wait for it to decompose without much thought. It’s easy, free, and requires little input.
Indoor composting, however, takes more time and generally requires an investment into special equipment. Many of the biological factors that help break down organic material are difficult to manage inside.
Improper management can lead to unpleasant odors, moldy ingredients, and flies. The food scraps you so diligently saved to make black gold end up in a trash bag in a landfill, and your eco-friendly composter goes right along with it.
The good news is that there is a way to make compost in your kitchen. Start by determining where you have space for a compost bin, and then decide how much time, money, and effort you are willing to devote to the composting process.
Indoor Composting vs. Indoor Compost Collecting
Before you begin searching Amazon for indoor composter, it’s important to understand the difference between indoor composting and indoor compost collecting.
Indoor composting is the process of collecting organic material and providing it an area to decompose inside a container in your home.
Indoor compost collecting, however, is simply collecting compostable materials in a container with the intent of transporting them to an outdoor compost pile. Or, to put them out for collection with your trash and recycling.
This distinction may seem obvious, but it’s important because many products listed as indoor composter are actually designed for compost collecting. These products are basically glorified trash cans with green bags and some ventilation.
Indoor composting is possible but difficult. Therefore, specialized containers that actually allow material to decompose are costly. Many indoor bins and systems have multiple trays or units for removing finished compost. They may also have activators or other materials to add into your food scraps to aid decomposition.
Generally speaking, indoor composting systems require modifications to prevent smells and decompose food quickly. These extras require time and supervision, making indoor composting a delicate and refined process.
Challenges Of Indoor Composting
Organic material naturally decomposes outside, where it is exposed to sunlight, moisture, bacteria, micro and macro organisms, and varying temperatures.
Hopefully, these conditions are not present in your kitchen.
An indoor compost container eliminates almost all of the factors necessary for decomposition by nature of the placement and then tries to recreate them artificially. This can work, but it requires planning and an understanding of the unique challenges you face when composting organic material indoors.
1. Lack of carbon ingredients
Compost needs a mixture of 2 parts carbon to 1 part nitrogen in order to decompose quickly and without odors.
Outdoors, this is easy, because carbon-rich ingredients like dead leaves and twigs are plentiful.
However, this can be more challenging in your kitchen, where almost all food scraps are rich in nitrogen. When compost is too heavy in nitrogen, the mixture begins to expel ammonia, which is what gives trash its trademark odor.
You can make up for this by adding brown, carbon-rich material from around your house. Common household ingredients include:
- Shredded paper
- Shredded cardboard
- Coffee filters
- Uncoated paper plates
Wood ash is another common brown material, but it can alter the pH drastically, so it is better suited for outdoor compost piles.
Indoor compost bins are small, so successful decomposition requires the ingredients to have a large surface area for bacteria to work their magic. The smaller the size of the ingredients, the greater the surface area.
Shred these ingredients as small as you can with scissors or a paper shredder. Indoor compost bins are turned frequently, so it is less likely that small particle sizes will form dense, matted layers like in outdoor bins.
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2. Lack of soil microbes
Soil microbes are a key component in decomposition, but they’re hard to find (hopefully) under your kitchen sink.
Fortunately, there’s a simple fix.
Don’t spend money on compost accelerators. These are pricey mixtures full of bacteria that are naturally found in a handful of garden soil. Add a few tablespoons of soil from your lawn or potted plant, and your compost bin will have the microorganisms it needs to start decomposing.
If you can’t get your hands on any natural soil for some reason, Paul does have a list of his recommended compost starters here.
3. Lack of sunlight
Sunlight helps heat compost piles, which speeds up decomposition. It also helps airflow as moisture evaporates and moves up through the pile.
Organic material can decompose at lower temperatures, but it is more likely to smell or mold.
You can combat this by more frequent turning, and placing your composter in a warm area.
4. Lack of airflow
Airflow is important for maintaining aerobic conditions within your compost pile. Beneficial bacteria need oxygen to decompose organic material, but they are quickly outnumbered by harmful bacteria when there is a lack of aeration.
When a compost pile is outside, it will be exposed to the elements, which allows air to flow freely through the materials.
However, when a pile is built inside a plastic container, it’s difficult to maintain aerobic conditions.
Frequent turning can introduce oxygen into the compost container, and keep beneficial bacteria active.
Is Indoor Composting Worth It?
Outdoor compost piles can produce at least a few cubic feet of usable organic matter. Piles are large enough to take in large amounts of yard waste, and the end product will adequately amend a small vegetable garden. It helps recycle waste and puts nutrition back into the soil.
Indoor composting containers are generally for people with no real yard space. There’s no room for a pile outside, so they move it inside. Indoor containers are small, and they produce very little compost. Indoor compost systems can be expensive, require more maintenance, and are prone to offensive odors.
So, is it worth it?
The goal of outdoor composting is to have a place to put the waste and create a nutritious soil amendment. But, for indoor composting, the goals change.
Indoor composting is geared towards waste management. It is almost purely for decreasing the amount of vegetable waste that goes into your garbage can. The handfuls of compost that you get every few months can be added to a potted plant or vertical vegetable garden, but it’s not enough to amend large raised beds or gardens.
Before you commit to setting up an indoor composting system, evaluate your goals. If you want to reduce the amount of waste you send to the landfill, indoor composting is perfect for you. If you want to be able to keep up with the needs of a 4’x8’ raised veggie bed, you may need to look at additional fertilizer methods.
Traditional Indoor Composting Containers
Choosing an indoor compost container mostly comes down to aesthetics.
While both of these composters will function inside, they will perform much better if they are in the sun. Putting them on the porch once per week will help the compost stay warm and active, which reduces smells and speeds up decomposition.
5-gallon bucket DIY compost container
Buckets make perfect composting containers because they’re readily available and easy to modify.
For this project, you will need:
- 5-gallon bucket with lid
- Large drill bit
- Screen material (small enough to keep out bugs)
- Hot glue gun or industrial glue
- Shredded paper or cardboard
- First, drill holes in the lid for aeration. Oxygen is an important factor in decomposition, so drill as many holes as you can without risking the integrity of the lid.
- Next, cut out your screen material to cover the inside of the lid. Use hot glue or industrial glue to attach the screen to the underside of the lid.
- Put a few inches of shredded newspaper or cardboard in the bucket, and add a handful of soil.
That’s it! Now you’re ready to start composting. When you add veggie scraps to your bucket, chop them into small pieces so they decompose quickly. For each inch of veggie scraps, add two inches of shredded paper or cardboard.
If you mix the compost weekly, it should not smell. The bucket should keep out insects and pests, as long as you don’t add animal products like meat or dairy.
This method will take at least a few months to create compost.
Try to store your compost bucket in a warm area. Cooler temperatures will hinder decomposition.
Cute indoor composter
Almost all indoor composts bins are actually compost collectors. We found one composter that is aesthetically pleasing and has been successfully used indoors. However, it was created for outdoor use, so it will take longer to make compost in your kitchen.
The Cutest Composter In The World (link to Amazon) is a black, 17-gallon plastic compost bin. It is 21.5” tall, so it should fit under most kitchen sinks. You can also set it next to your garbage can for easy access.
The price is about average for functioning miniature compost bins.
Fill the bin at least halfway with shredded cardboard and paper. As you produce veggie scraps, chop them up and throw them in. Rotate the bin a few times per week, and you should have compost within a few months.
This composter works quickly outside where it can absorb heat from the sun. It can take much longer under your sink depending on the temperature inside your house.
Vermicomposting is the best indoor composting solution. A vermicomposting system uses red wiggler worms to break down organic material and then uses the worm castings as a potent fertilizer.
This eliminates the need for external heat and turning the bin, and although it produces small amounts of end product, it is potent enough to be used on a large scale. Worm castings are a concentrated mixture of essential vitamins and minerals and contain 50% more organic matter than garden soil. In fact, vermicompost is a better fertilizer than manure!
Worm bins are best for kitchens because they need to be kept cool and dark, so they do well under a kitchen sink.
Worms bins are easy to make and fairly cheap to purchase. Again, it comes down to aesthetics.
Plastic tote worm bin
To make your own worm bin, you will need:
- One deep plastic storage tote with lid
- One shallow plastic bin to use as a drain pan for the storage tote
- 1/8” drill bit
- Shredded paper
- Fine plastic mesh
- Waterproof glue
- 1 lb. Red Wiggler worms
- First, make sure your deep storage tote fits inside the shallow bin. As liquid from the tote leaks out, the bin will catch it so you can use it on your plants. This liquid is high in nutrients and a valuable byproduct of the composting process.
- Use the drill to make holes 1” from the top of the plastic tote all the way around the sides. Next, drill two holes near the bottom of each corner for drainage.
- Cut plastic mesh to fit over the holes, and glue it to the inside of the tote. This will prevent the worms from escaping.
- Place the tote inside the bin, and fill the tote about 3” deep with shredded paper. Add another 3” of soil, and mix it in with the paper.
- Sprinkle the mixture with water, and add the worms. Let them settle in for a day before adding kitchen scraps.
- Collect fruit and vegetable scraps from the kitchen, and chop or crush them into smaller pieces. Gently dig shallow holes in the bedding and place the scraps inside. Cover the food with soil and paper, and put the lid back on.
Avoid disturbing the worms too often by only feeding them once per week. This helps them break down food quicker, and prevents frequent moisture and temperature changes. Click here to learn how to keep a worm bin in balance with proper moisture, temperature, and more so that they don’t try to escape!
When liquid builds up in the drainage bin, scoop it out and use it (sparingly) as a fertilizer. To avoid burning plants, dilute with an equal amount of water. Leaving too much water in the bin can actually put your worms at risk of drowning.
When the tote reaches the air holes near the top of the tote, begin feeding the worms on one side of the bin. After a few weeks, the worms will migrate to that side, and you will be able to scoop out the finished compost on the other.
You can either even out the remaining compost and begin feeding again, or separate the worms from the compost and start over. Red wigglers multiply quickly, so you may need a second bin after a few rounds of compost. (If your worms aren’t growing this is often a sign of having too many). Or, let them loose with the compost into the garden. Be sure to read Can Earthworms and Redworms live together? to understand the differences in how these worms interact in your garden.
Uncle Jim’s HOT FROG Living Composter
This system is designed for maximum aeration without allowing the bedding to dry out. The liquid will collect in the bottom, and a spigot allows you to drain it mess-free.
It’s a little under 2’ tall, so it should fit under most kitchen sinks.
I know growers who use Uncle Jim’s for large-scale vermicomposting. Their products are excellent and their customer service is incredible.
You can purchase Uncle Jim’s Hot Frog Living Composter at his website.
This composting process is fairly new to the Western world, although it’s apparently been in use for centuries in Japan.
Bokashi means “fermented organic material,” so this is more of a pickling process than a composting process. Most composting systems need aerobic conditions in order for the bacteria to break down organic material, but this system uses anaerobic fermentation.
The major benefit of Bokashi composting is that you can add animal products and bread to the composter. The fermentation process breaks down the proteins in these materials, and the airtight bucket keeps out pests.
The end result isn’t exactly compost. Anaerobic decomposition always results in acidic organic matter, and this “compost” is so acidic that you can’t use it near plants for at least a month.
According to manufacturers, the Bokashi composting process works like this:
- Leftover food scraps are coated in inoculated bran and pressed into the Bokashi bucket
- Inoculated bran is layered throughout the bucket
- Once full, the bucket is sealed tightly and left in a cool place
- Use the spigot to drain the compost tea every other day
- After ten days, the organic material will be fermented, and can be buried in a fallow portion of the garden, or added to a compost pile
- Wait at least a month before planting anything in the area
The problem with Bokashi
Bokashi composting isn’t composting. It’s basically canning trash in a (very expensive) bucket.
Most people searching for indoor composting solutions have limited outdoor space. If you need to add fermented waste to a compost pile, or dig it into a large garden space, then you might as well just compost outside to begin with.
What would a Bokashi fan do with their 5 gallons of pickled veggie peels once it’s fermented if they don’t have a large garden or compost pile? It’s too acidic to add to potted plants. The materials don’t break down at all; they’re still completely recognizable.
So, what’s the point?
One blogger tackled this issue by blending the soil factory fad with the Bokashi fad. (source)
If you live in an apartment, or an area with limited outdoor space, you can fill a tote with coir or peat and mix in the fermented waste. After a few weeks, the dry material will absorb the liquid, and the solid foods will break apart. In theory, this will create a soilless potting mixture. You can also experiment by adding shredded newspaper, cardboard, and other carbon-rich ingredients.
If you do want to try Bokashi composting, have a plan for using the fermented mixture. Don’t pour it on potted plants or raised beds.
Composting in the kitchen is possible, but it’s difficult. The easiest solution is vermicomposting, followed by a simple 5-gallon bucket system. Bokashi takes a great deal of devotion, but it does help to break down tough food scraps.
You won’t produce much finished compost, but indoor composters produce compost tea, which makes an excellent fertilizer for potted plants.
What do I do if my indoor compost bin starts to smell?
Compost should smell earthy and sweet. If it starts to give off an unpleasant odor, it probably has too much nitrogen, or it’s too wet. Add some dry shredded paper and mix it up.
Read more about diagnosing common composting problems here.
Why do my compost ingredients need to be chopped and shredded?
Indoor compost bins are much smaller than outdoor piles. They are also closed off from bacteria and the elements that help break down materials. Chopping and shredding the paper, cardboard, and food scraps help to mechanically break down the compost ingredients so the bacteria have more surface area to work with.
To learn more about shredding newspaper for compost, read our article here.