Bokashi Composting: A Step-by-Step Guide to Indoor Composting

Gardeners know the value of compost, but it can be tricky to find space to produce enough compost for an outdoor garden or even an indoor plant collection. This is where bokashi composting comes in handy. You don’t need much space or equipment to reap the benefits of bokashi composting. In fact, you can even keep a bokashi composting bin conveniently indoors. The bokashi method enables you to turn meat scraps, dairy products, cooked leftovers, and more into usable nutrients for your soil and plants. Also known as bokashi fermentation, this composting process uses beneficial microbes to pickle food waste that isn’t well-suited for traditional composting. Keep reading to learn more about bokashi composting.

bokashi bucket — Bokashi composting is a two-step process that turns kitchen waste into a rich soil amendment.

What is bokashi composting?

Bokashi composting is a two-step process that ferments organic matter and then mixes the resulting product with existing soil or compost in order to complete its transformation. “Bokashi” is a Japanese word which, directly translated, means “to blur”. After the bokashi fermentation process takes place, kitchen scraps feel softer and look less distinct—in this sense, they are blurred or fading.

We have bokashi composting thanks to Dr. Teruo Higa, a retired professor from the University of the Ryukyus in Okinawa, Japan. Dr. Higa originally stumbled upon the idea of combining multiple types of microbes by accident. After performing experiments with individual microorganisms, the horticulturist combined them in one bucket for disposal. Rather than rinse the bucket’s contents down the drain, he poured it onto a patch of grass. The grass flourished unexpectedly as a result.

By 1980 Dr. Higa had perfected his mixture of “effective microorganisms” or “EM.” Working together, these microorganisms make bokashi composting possible.

The benefits of the bokashi method

There are many benefits to using this technique. Bokashi composting requires much less space than traditional composting. It’s also speedier. And, because you can include many additional types of kitchen waste, operating a bokashi system can help you keep lots of organic material out of the landfill.

In two to four weeks, your food scraps break down enough for safe transfer to an outdoor compost pile or composting bins. Alternatively, the kitchen waste you ferment can simply be buried underground or buried inside a large container of soil where it rapidly completes its transformation into rich, new garden soil.

Another benefit is that you also have access to bokashi tea—a natural byproduct of the bokashi fermentation process. Used at full concentration, this leachate is a perfect natural drain cleaner. Also known as bokashi juice, the liquid can be a useful fertilizer in garden beds. However, its nutrient content varies and, because it’s highly acidic, it must be diluted first. A ratio of 200 parts water to one part leachate is ideal.

indoor compost bin — You can DIY or buy a bokashi compost bin, but it must be airtight. Photo courtesy of Gardener’s Supply Company.

How bokashi composting works

With bokashi composting, the effective microorganisms, Lactobacillus and Saccharomyces, work together in an oxygen-starved environment to ferment food waste. During this anaerobic process, beneficial Lactobacilli bacteria produce lactic acids. This, in turn, makes conditions just right for acid-loving Saccharomyces yeasts to further break down organic matter. Harmful microorganisms can’t flourish in this high-acid, low-oxygen environment. This makes it possible for the beneficial bacteria and yeasts to outcompete them and successfully ferment your waste in the process.

spray for indoor compost — You don’t need a lot of supplies for bokashi composting. You need an airtight container and a granular or liquid inoculant. Photo courtesy of Gardener’s Supply Company.

Supplies needed for the bokashi fermentation process

The microorganisms needed for bokashi composting are available via dried inoculant preparations which specialty suppliers often make with molasses and rice or wheat bran. This inoculated bran product is usually sold as “bokashi bran,” “bokashi flakes,” or “EM bokashi.”

As for the fermentation environment itself? Beginners may have the best luck with commercially available bokashi bins, since they’ve been designed expressly for this process. They’re airtight and feature reservoirs and spigots to accommodate the liquid runoff produced during fermentation.

Of course, you can make your own bokashi bucket system without a spigot. Here are two options:

DIY bucket-inside-of-bucket system—Get two identical, airtight buckets with lids. (When these buckets are nested, they must form an airtight seal.) Using a one-quarter-inch drill bit, drill 10 to 15 evenly spaced drainage holes in the bottom of one of the buckets. Place this drilled bucket inside the other. With this system, you’ll follow the bokashi fermentation steps; however, you will need to drain off the leachate periodically. To do this, keep the lid on your bokashi bucket and carefully separate it from the outer bucket. Pour off the liquid and re-nest the pair of buckets.
Non-draining bokashi bucket—Choose a bucket which has a lid that fits snugly enough to be airtight. To sop up any fermentation leachate, incorporate absorbent materials like shredded newspaper or cardboard with your food layers. Before adding your first food waste layer, line the bottom of the bucket with a few inches of shredded cardboard liberally sprinkled with bokashi flakes.

bokashi starter — Bokashi starter, or bran, is a dried inoculant to speed up fermentation of the organic matter. Photo courtesy of Gardener’s Supply Company.

Where to put your bokashi bucket

Once you’re all set up, look for a good spot to keep the bucket. Relatively warm, small spaces are perfect for bokashi ferments. You can keep your bokashi bin under the kitchen sink, in a closet, pantry, or recycling area. As long as you carefully follow the bokashi composting steps and make sure your airtight bucket’s lid is tightly sealed, you should not detect any odors or attract insect pests.

The basic how-to of bokashi composting

The process of bokashi composting is relatively simple. Below you’ll learn the 5 basic steps to getting started.

Step 1 – Sprinkle the bottom of your bucket with bokashi flakes until it’s nearly covered.
Step 2 – Add one to two inches of chopped, mixed kitchen scraps.
Step 3 – Sprinkle more bokashi flakes over this layer. As a general rule, you’ll use roughly one tablespoon of bokashi bran per inch of kitchen scraps—several tablespoons of bokashi bran per bucket in all. Repeat steps 2 and 3 until you’ve added all of your kitchen waste.
Step 4 – Cover the topmost layer with a plastic bag, tucking in the edges so it makes a good seal. Eliminate potential air pockets by pressing down on the layers with the flat of your hand. (A potato masher also works well for this.)
Step 5 – Snap on the airtight lid for a tight seal.

Depending on the amount of food waste generated, you can either refrigerate it until you’re ready to add new bokashi layers or you can add kitchen scraps daily. When adding extra layers, remove the plastic bag and repeat steps 2 through 5. Once your bucket is full, let it ferment for two to three weeks, periodically draining off any leachate as needed.

Bokashi composting technique — A wide variety of foods can be composted – from raw food scraps (including bones and meat) to cooked dishes like shrimp tails and rice.

What to add (and what not to add) to a bokashi system

From leftover eggs Benedict and chocolate cake to old cheese and shrimp tails, nearly anything is fermented with this technique. Meat, dairy, bones, and oil-rich, cooked foods are all acceptable bokashi composting candidates. But that doesn’t mean you should throw these items into your bucket whole. As with traditional composting, organic matter breaks down better if you chop it into smaller pieces and mix well. This creates more surface area for the bacteria and yeasts to access.

Have lots of meat to add? Include fruit waste and other sugary scraps along with it. This gives EM much-needed fuel to ferment that tough protein. There are some items you shouldn’t include. Milk, juices, and other liquids may increase the likelihood that your bucket will go bad. Also, skip foods covered in heavy amounts of green molds. The efficient microorganisms might be able to outcompete some of this, but, if they fail, fermentation’s a no-go.

How long does bokashi composting take?

On average, it takes two to four weeks for the material in your bokashi bin to ferment. When the process is complete, you should see a fair amount of fluffy white mold growing on and in between your food items. And once you’ve buried your fermented material, it can take three to six weeks to finish its transformation.

Does bokashi composting stink?

Because bokashi fermentation takes place inside an airtight container, you shouldn’t be able to smell its contents. When your bokashi bucket is open or when you are draining leachate, you should only smell something akin to pickles or vinegar. If you detect a foul odor, you might have some trapped air pockets. Fix these by compressing each food layer as much as possible. You might also have too much liquid in your bucket. Drain off your fermentation leachate regularly to prevent this. Not sprinkling enough EM on each layer can also cause foul smells, so use plenty of inoculant as you go.

What to do with compost from a bokashi bucket

Once the organic matter is fermented, finish composting it by:

Burying it at least one foot deep outside – Just don’t place it too close to established plants, since it can initially acidify soil pH. You can also choose to bury it deep within a large, soil-filled container. In three to six weeks, soil-based microorganisms will finish breaking down the organic matter.
Burying the fermented material deep in the center of your traditional compost pile – Because this new material is full of nitrogen, add plenty of carbon (like shredded cardboard or dried leaves) simultaneously. Leave the fermented material buried within the pile’s center for about a week. Then, mix it into the rest of the pile.
Adding small amounts of the fermented material to vermicomposting bins – Eventually, your worms will gravitate to the new material and covert it to vermicompost. (Just be careful not to add too much of the acidic material at once or you risk throwing off their habitat’s pH.)

indoor compost bucket — Liquid bokashi spray is made from beneficial microbes that start and speed up the fermentation process in your bokashi bucket. Photo courtesy of Gardener’s Supply Company.

Where to buy bokashi supplies

With this composting technique becoming more common, it’s now easy to source supplies. In addition to Gardener’s Supply Company, Epic Gardening, a California-based online retailer, sells complete bokashi kits and effective microorganisms in 5-, 10-, 25-, and 50-pound bags.

Based in Texas, Teraganix is another online shop which offers bokashi systems and even supplies for making DIY bokashi inoculant. (For long-term savings, you can inoculate sawdust, spent grains, or similar materials on your own.)

Mighty microbes

Whether you’re trying for zero-waste living or you simply want to improve your garden soil, bokashi composting is a powerful tool. Keep a bokashi bucket indoors and load it with food waste that’s ill-suited for traditional compost piles or worm bins. With just a little effort—and in a surprisingly short time—you’ll have fermented, pre-compost that you can then bury underground, place in a large, dirt-filled container, or add to your regular compost. After a couple of weeks, the fermented waste will have broken down into nutrient-rich matter, and you can safely plant in it.

For more information on composting and soil building, check out these detailed articles:

Are you interested in trying bokashi composting?