Composting is nothing new. Nature’s been in the recycling business since the beginning of time. Ecosystems recycle waste through bacterial action, and humans have consciously taken advantage of this process for millennia.

What is new this century is that about half of humanity now lives in urban areas, a trend that is only accelerating. However, indoor composting is an easy way to turn urban organic garbage into a valuable, nutrient-rich and odorless soil amendment for your garden.

What Exactly is Compost?

All around us float bacteria, spores, bug eggs, and other invisible things seeking a perfect home. Anything organic, moist, and warm will do. When they find it, the microbes will colonize and build immense “cities.”

These communities are incredibly resilient and devour just about anything organic. That’s why food spoils and dead things rot away. The microscopic life forms break down some ugly toxins, too.

The waste product of this decomposing process is the small organic molecules that plants must absorb to build their bodies and thrive. All this activity also produces heat. Manure piles get hot enough to steam and rotting hay can set a barn on fire. However, the heat in composting material is normally just enough to kill pathogens and the seeds that sprout weeds.

While fungi living in this system require time to develop undisturbed, they still act as managers, maintaining heat and producing carbon dioxide and ammonium (NH4), the form of nitrogen that plants can absorb. Eventually, the fungi take over the compost pile. At that point, even tough fibers end up unrecognizable. Leave the rotting stuff around for a while after it’s cooled and the fungi keep working to break down woody lignins and fully decompose phytotoxins that can harm plants.

OK, I’m in. But Where do I Start?

To start a successful compost pile, make those microorganisms an offer they can’t refuse: a safe and comfy home with lots to eat. A waterproof, knee-high plastic bucket with a tight lid, a drain faucet near the bottom to get rid of excess water, and some drilled holes in the walls for aeration is perfect for a basic indoor composting system.

Start with a bunch of old crumpled newspapers and a couple of handfuls of good chemical-free dirt, which should contain billions of little beings ready to colonize. You could also buy a compost starter, which is guaranteed to have all the critters you’ll need.

Next, add organic waste including food scraps, yard waste, wilted flowers and leaves, and just enough water so that the mess feels damp but not wet when you stir it all up. Keep the bucket in a place where temperatures won’t get below about 50˚F. Every couple of days, stir the contents again so they are well-aerated and don’t get warmer than 122˚F. In a few weeks, or maybe longer, you have compost.

On a larger scale, composting is a multi-step and closely watched operation with calculated inputs of air, water, and a mix of well-shredded materials that balance carbon and nitrogen levels. Regular turning is essential. Aerobic bacteria need air and moisture, as do tiny arthropods, worms, and fungi. Until you decide to make a living at making compost, however, forget the large-scale logistics.

Of course, the indoor composting process is not foolproof. Sometimes beginners end up with a disgusting mess. Toss it in the yard or, better yet, bury your mistakes. But, why did things go bad? Simple: the environment was either too hot or too wet and nasty anaerobic bacteria took over. No matter; wash your equipment with soap and start again.

What About Bokashi Compost?

The Japanese bucket system for food waste, known as bokashi composting, is a great indoor system for fast, anaerobic bacterial action. (Yes, the same nasty things that ruined your first indoor compost). It’s more controlled, miraculously odor-free, and, as I mentioned, works faster than the simple aerobic set-up described above.

In less than a month, you can have enough beautiful compost to bring joy to many house plants and to enhance the nearest garden. Naturally, the same process occurs without human intervention in heaps of dead leaves, outdoor compost piles, or forest floor debris. It just takes much longer.

You can buy everything you need, including concise directions, online. Or, if you’re a DIY enthusiast, you can assemble a kit yourself for a low cost. The list of equipment you need is short: a knee-high plastic bucket with a tight-fitting lid and a tap or pluggable hole at the bottom for easy emptying of excess liquid. No drilling of air holes for this method; it’s anaerobic.

Next, you’ll need food waste, chopped to thumb-size or smaller. Don’t toss it in just yet, though. First, gather up a carbon source to provide super-feed for the tiny lifeforms who will call the bucket home. Wood chips, sawdust, old newspapers, or grain bran are perfect. After this is the microbial starter, or your source for bacteria. In warm weather, it can be fresh, rich soil loaded with billions of bacteria.

If you want to get fancy, set up a big bowl with a lid then fill it with sheets of newspaper, sawdust, or grain bran. Mix a cup of yogurt with a couple of cups of water and a few spoons full of molasses or other natural sugar.

Pour this over the paper and toss it to coat the surface. Put it all in a plastic bag and let it soak a day or two. The soaked paper is now a carbon source that is also your lactobacillus starter.

Now, you are ready to prepare your bacterial paradise. Layer the food waste, microbial starter, and carbon source in tiers. Add just enough water so that the lasagna feels nice and moist but never fully wet. Finally, on top of the layer-filled bucket goes a plastic sheet and then the tight lid.

In winter, leave the bucket in an indoor corner or closet. In warmer weather, it will be happy indoors or outdoors in the shade. The warmer environment will cause the composting process to go a little bit faster.

Either way, check the bucket every few days. Give it a shake so excess liquid makes itself heard. Drain off this rich compost tea through the tap at the bottom of your bucket and spray it on plants or soil. If you don’t keep a garden in winter, you can freeze the compost tea for use in the spring. Remember, though, that it’s alive and will die if thawed and ignored more than a few days.

Eventually, the contents of your bokashi system will turn into beautiful solid compost. Once you’ve harvested it, just clean up your equipment and start the next batch to keep the cycle going.

No matter which method you choose, indoor composting is a quick and easy way to transform all kinds of food waste into a valuable organic resource for your garden or growroom.