Bokashi Compost Buckets: An Easy DIY Method
Most stationary and tumbler-style composters handle plant materials, paper and cardboard, some manures, and the occasional eggshell. Vermicomposters can handle all of those as well as occasional rice or pasta that can gum up a tumbler composter or draw pests if added too frequently. But only one method of composting can handle all of the above as well as dairy products and meats, and that is bokashi composting!
In this post, I’ll show you bokashi composting DIY style from building your bokashi bucket all the way to the finished soil. The only things required to get started with doing bokashi are a couple buckets, some bokashi bran, your kitchen waste, and time. It’s surprisingly easy to do. Best of all, you’re reducing your waste while improving your garden soil. So let’s get this started!
What Is Bokashi Composting?
The term “bokashi” is Japanese, and it loosely translates to “fermented organic matter”. And in bokashi composting, that’s essentially what you are doing: you’re pickling your food waste. To do this process, you use a refuse product (like bran, wheat mill run, rice hulls, dried spent grain from breweries, or even sawdust or finely-shredded newspaper — anything fine or almost granular) that has been inoculated with EM, or “effective microorganisms”. It’s also sometimes referred to as “effective microbes”. The inoculated product is commonly called bokashi bran, regardless of what it actually is made from.
How Does Bokashi Work?
Sprinkle a layer of bokashi bran into either a commercial or DIY bokashi bucket, then add your refuse in layers with bokashi bran mixed into it and sprinkled over the top. By doing this, you slowly build a bucket full of your kitchen waste. You’ll need to regularly drain out any liquid from the bucket so that it doesn’t smell bad. Bokashi is an anaerobic process, which means that it’s done without air, so you must pack your waste down solidly to press out any excess air and keep an airtight lid on the container.
Once you have a full bucket, add one last thick layer of bokashi bran over the top, and then put on the lid and place the filled bokashi bucket somewhere to ferment for at least two weeks uninterrupted. When the fermentation process is done, bury the contents of the bucket (commonly called “pre-compost”) in either a trench in the yard or in a prepared bokashi processing box. You can also bury fermented bokashi in a worm composter, add it to a compost tumbler or bury it in a compost pile if you prefer – pickling it makes it less appealing to wild animals, although composting worms love it.
The microorganisms will continue their work in breaking down the plant material, and it’s usually gone quite quickly shortly thereafter, leaving you high-quality compost.
What Organisms Are In Bokashi Bran?
Most effective microorganisms come from one of three families: Lactobacillus, Saccharomyces, or Rhodopseudomonas.
Lactobacillus is a very common bacterial family and is known as a probiotic for human use. There’s a wide variety of lactobacillus species, but most of them are beneficial in the bokashi process. They’re commonly used for fermenting food like sauerkraut or making yogurt.
Saccharomyces is the yeast family. Yeasts have been used in fermentation for centuries, and are essential to the making of products like brewed beverages (beer/cider), certain sodas like root beer, and some foodstuffs like bread. To do this, yeasts eat protein that’s resident in grains, meats, or other food components, thus breaking it down.
The Rhodopseudomonas family of bacteria is a naturally-occurring resident in soils and some marine environments. In bokashi, it converts atmospheric carbon dioxide into biomass, but it has a secondary purpose as well. One variety of Rhodopseudomonas breaks down lignin, which is a major component of wood and other plant materials.
With these three types of bacteria working on your waste products, they can fully initiate the composting process for pretty much any plant or animal material.
Bokashi Bucket DIY: How To Build Your Bucket
The process of making a bokashi bucket is simple. You will need two five-gallon buckets, something to either slice or drill holes in plastic, one tightly-sealing lid, and a few household items. I find that buckets are relatively inexpensive at big-box stores. Sometimes, you can even get used buckets for free from people in the food service industry!
Creating Drainage Holes
Begin by making sure that your two buckets will tightly and snugly fit together. You want there to be as little airspace between the top and bottom bucket as you can manage. You should still be able to lift one bucket out of the one below it when they’re stacked. Once you’re sure they stack tightly together, take your inner bucket outside with some tools to get started.
Because bokashi compost can still create liquid as the material in the bucket breaks down, you need to have a way to drain out this liquid. For me, that’s by making holes or slots in the bottom of the inner bucket. I used a circular saw for this purpose, but you could also just drill a number of holes in the base of the inner bucket.
The liquid will then collect in the outer bucket as it drains off, creating bokashi tea. This powerhouse liquid can be used in a number of ways, but more on that later!
Using the circular saw, I just cut four slashes in the bottom of the bucket to provide even drainage across the base. If you’re opting to do this method, I highly advise not trying to go through the center part of the bucket as it’s typically tougher to cut through and can break your bucket. Were I to do this again, I’d opt to just drill a couple dozen scattered holes in the bottom, but this method drained extremely well.
Use a piece of sandpaper or a file to take off any loose plastic bits that jut out around the cut edges or drill holes. Then, take your newly-drilled inner bucket and place it back inside your outer bucket. Snug it down tightly. If you find there’s any air space at the top of your bucket, I found that using stacked large rubber bands around the outside of the inner bucket that rest at the joint where the two buckets stack together worked well. The goal is to make the interior of your bokashi bucket as airtight as you can.
If you want to make this more like a commercial bokashi bucket, you can add a spigot to drain off the bokashi tea. It’s not necessary, although it does make it easier to drain. I opted not to for this first bucket, but may in the future.
Picking The Right Lid
Let’s take a moment to discuss lid options. For most buckets, there are two choices available. First, there’s a snap-on lid like the one shown on the left. On the right, we have a screw-on paint bucket lid.
Paint bucket lids provide a perfectly-airtight seal… once. After that, while the gasket in the lid gives a little extra protection against air getting into the bucket, it also provides a space where food refuse or other material can build up and get stuck, and the gasket may become loose. Paint bucket lids also cost about twice what normal snap-on lids do, and your bucket needs to be able to handle a threaded lid, which some won’t.
I personally chose the snap-on lid, and it worked just fine for this purpose. But if you don’t mind regularly cleaning off the gasket to remove any bits of bokashi or specks of food that might have gotten worked up in there, the paint bucket lid’s great too.
Loading And Maintaining Your Bokashi Composter
Now that your basic DIY bokashi bucket is ready, it’s time to get to the actual bokashi composting process!
Lining Your Bokashi Bucket
Take your lid and lay it on top of a scrap of fabric or wire mesh. I used a piece of old landscape fabric, but you can opt to use old T-shirt material, kitchen towels, some fine hardware cloth, or any number of other options. Roughly cut a square that’s just a bit larger than the lid. This will provide a barrier in your bucket to keep any soft material from getting stuck in your drainage holes or slots.
Place your material in the bottom of the bokashi bin, being sure that it goes a little up the sides. At this point, it’s time to add some bokashi bran.
For this early process, I chose a commercially-prepared bokashi bran from Bokashi Brothers. This high EM bokashi has been double-fermented to thoroughly innoculate the bran with plenty of effective micro-organisms. It’s then dried to create an easy-to-use option. However, you can make your own bokashi bran using liquid EM1 solution, or even by culturing your own effective microorganisms. If you want to save yourself a lot of time, we’re now huge fans here at Epic Gardening of the SD Microbes BierKashi Bokashi Blend, made from spent brewery grain — they recycle a waste product to help you recycle your waste products!
Filling Your Bokashi Bucket
Once your material is in place, take a couple of handfuls of bokashi bran and sprinkle it inside to create a fine coating at the bottom of your bokashi bucket. This provides a kickstart layer of EM for your food waste.
Now it’s time to start adding your food waste — and that means almost any leftover food you have on hand!
The more finely you hack up your waste products, the quicker they will break down after being fermented. To start off my bucket, I hacked up the rind of a watermelon and then added some leftover onions from the previous night’s dinner. You can also add leftover bread or pasta, meat scraps, bits of cheese, and salad that’s gone past its prime… you get the idea.
For each inch of material, add more bokashi bran. I just sprinkle it liberally across the surface of the food waste, trying to get a good spread so that the EM can get to work on the waste. If I’m adding the EM to something very dry, like stale bread, I use a spray bottle first to mist the top surface of the bread with water. I’m not trying to soak the bread down, just providing a damp surface for the EM to work its way into.
What You Should Not Add To Your Bokashi Bucket
The only food items you shouldn’t add to your bokashi bucket are oils or large bones. This isn’t because they won’t break down, because they will. Oily materials take a whole lot more bokashi bran to process. The oils are very slow to break down, and liquid oil itself will just go straight through the drainage holes in the bucket without composting at all. Extremely large bones will also break down, but they are very slow to process. Small bones like chicken bones or the like tend to be a little quicker, but are still going to be around for a long time.
It’s also a good idea to not add food that’s gone bad. If you have a container of unidentifiable something in the fridge, that might be best put directly in the trash. This is not because it won’t compost, because it will. However, whatever has invaded that container might also take over the entire bokashi bucket. You’re trying to make pre-compost, not do science experiments!
While some people would like to compost their pet waste, that’s not the best idea in your regular bokashi bucket. Pet wastes come with many potential risks. Pet waste often has harmful bacteria in it, and may also be infested with worms and the like. If you do want to try to compost your pet waste, make a dedicated bucket for it – and never, ever, use that compost near any edible crops. But to be honest, I don’t recommend doing it, even if you’re trying to reduce your waste stream. Opt for other ways of disposing of pet products.
Keeping Air Out Of Your Bucket
Bokashi is an anaerobic process. This means it happens in the absence of air, and it’s important for you to keep out as much air as you can.
When you have added food waste to the bucket and sprinkled it liberally with bokashi bran, you should use a potato masher to pack down the waste tightly. This helps reduce the air in between the remnant food. Then, use something as a top cover to sit directly on top of the food. I found an old plate at a thrift shop that I use as a cover, along with some plastic wrap.
In the photo above, you can see paper. I used that for the purposes of the photo because the plastic wrap just wouldn’t show up. Cut a piece of plastic wrap that’s larger than your plate, press it down into the bucket on top of the food waste to help keep air out, and place the plate on top of it. Then tightly put the lid on.
It’s important to only add food waste to your bucket when you have enough to create a layer. I have a compost bin on my kitchen counter where I put my kitchen scraps, eggshells, coffee, and the like. When the container is full, I’ll open up the bokashi bucket, sprinkle in a little fresh bokashi bran, and add the new layer. Then, bran goes over the top, I’ll pack it down, put the plastic wrap and plate on top, and close it up quickly. This helps prevent cross-contamination.
Bokashi Tea: What To Do With Bokashi Liquid
Bokashi tea is the liquid that gathers in that outer bucket over time. This liquid comes out of the food waste as it slowly ferments in the bucket, drains through your fabric, and down into the bottom bucket. It’s inoculated with some of the EM from the bran and may have a light vinegary odor to it.
It’s also really useful stuff. While I don’t personally use it as liquid fertilizer, some people do use it that way. If you plan on doing this, you’re going to want to do this every day or two, because you’ll want to use it when it’s fresh. Otherwise, it will start to develop a whitish mold on the top.
What I opt to use it for is as a microbial drain cleaner. Pouring the liquid down my kitchen sink has helped to keep my pipes free of food particulates, because the microbes grab onto any food waste in the pipes and start to break it down, freeing it from whatever it’s stuck on. To do this, you will need to directly pour your bokashi tea down the drain and let it sit in there for at least an hour or two, then rinse. Repeating this regularly will help the EM to break down any residual food that’s stuck in the pipes and will help you keep them clear.
What Happens If You Get A Contaminated Batch
So what happens if you open up your bokashi bucket one day to see greenish or blackish mold forming? Is this bad?
Actually, yes, it’s bad. This means that something other than your beneficial microbes has gotten into the bucket. That could be any number of other bacteria or fungi starting to attack your compost, and it needs to be dealt with quickly. The only mold color you should see in your bokashi bucket is white mold, and white mold is a sign that your bacteria is doing its job.
To fix this, use a paper towel to wipe clean any surfaces of the bucket that have started to show signs of infection. Once that’s done, spray a second towel with a Lysol-type cleaner, or moisten it with rubbing alcohol, and wipe down the inside of the bucket with that as well to sterilize it. I also usually clean off the plate and replace the plastic wrap if this happens, just to provide a clean upper surface. Try to avoid getting food waste on the sides of the bucket in the future.
If any of the greenish or blackish mold has formed on the food waste itself, you can either try to overwhelm it with EM, or remove it entirely. Either use a lot more bokashi bran and coat it entirely with the bran, which should take back over, or remove the molded surface and dispose of it normally. Coat the remaining bokashi with a thick layer of bran and go back to business as normal.
How Long Does Filling The Bucket Take?
This question is a tricky one to answer, and it’s because it partially depends on how long it takes for you to produce food waste.
If you produce very small amounts of food waste, it’ll feel like it takes forever to fill the bucket, and every couple of days you’re draining out the liquid. In cases like that, using a bokashi bin made out of smaller buckets is probably a good idea. You can find 2-gallon buckets at foodservice locations on occasion, or you can buy a commercial bokashi composter.
If you produce large quantities of food waste, this process can go a lot quicker. It may also go faster during the summertime when there’s an abundance of fresh fruit and vegetables, and thus a lot more fruit or vegetable remnants. My first 5-gallon bokashi bucket took me a month and a half to fill, and my second one took about three weeks. So be prepared to be flexible and patient. You will eventually get it filled up, and as long as you add bokashi bran every time you open that lid, you’re ensuring the EM will keep doing its job properly.
What To Do When The Bucket Is Full
Once you have filled your bucket and can’t fit any more food waste in it, put a nice thick coating of bokashi bran over the top. Use about double what you would normally use when you’re adding a layer. Then seal up the bucket as normal and leave it alone for at least two weeks, unopened. My first bucket actually sat untouched for about a month.
During that two to four-week period of time, the bokashi will continue to ferment through all the layers, pickling your waste. The microbes are hard at work during that time and are weakening the structure of the food inside the bucket.
When you finally reopen it again, you may see a layer of whitish mold on top of the food. That’s good! That’s a sign of a healthy microbial colony. At this point, the contents of your bucket are now bokashi pre-compost.
Converting Pre-Compost To Finished Compost
It might not look like a whole lot has happened to the contents of this bucket, but it definitely has.
If you look closely, you’ll see a whitish mold around the exterior of the food waste. In spots, it’s a bit fuzzy. That develops from two of the three most common bacteria used in EM and is harmless. Some of the vegetable and fruit matter has wilted. The contents have sunk down by a couple of inches, as can be seen from where the ring of bokashi bran shows higher up in the bucket.
This is bokashi pre-compost, ready to stick into the ground. There are multiple options that you can do at this point with that pre-composted material.
You can opt to place it into a vermicomposter and let the worms go at it. Composting worms absolutely adore bokashi. If you do this, dig a hole in your worm composter bedding, place small amounts of pre-compost into it, and cover them back up. The worms will devour it quickly, and it will take a lot less time for the worms to eat this as opposed to fresh food.
You can make a hole in your compost pile and add this to it, then cover it. The bokashi will break down at a highly-accelerated speed, becoming high-quality compost quickly.
You can make a soil factory. This is effectively a large box filled with regular garden soil, and you bury the bokashi in that. It will break down in there and disappear into the soil with good speed.
Or, you can opt to do what I did.
Burying Your Pre-Compost
I have brick-edged garden beds along the sides of my backyard. My soil is heavy clay, so I soaked it down with water to loosen it up, then used a shovel to break it up a bit more.
At this point, it was time to dig a large hole. Putting the soil into my garden cart, I dug a hole that was about three feet across and about eight inches deep in preparation.
Once I had the hole prepared, I grabbed the bokashi bucket and hauled it out to the hole, and promptly upended it into the hole. Here, you can see the landscape fabric that had been on the bottom of the bucket, along with what looks like a whole lot of untouched food. And it’s right about now that you might be questioning why bokashi is worthwhile. Trust me, it is. I’ll get to that soon!
Pick out the fabric that you’d used as a bucket liner, and then rinse out the inside of the buckets, dumping the water in with your food waste. This helps you to clean out your buckets, but it also ensures that all of the EM that was inside the bucket is now in the hole with your pre-composted material. Make a slurry out of the food waste and the rinsing liquid, trying to spread it out fairly evenly throughout your hole.
Begin adding the soil back into the hole. As you add it, be sure to mix the first few shovel loads through the food waste. You’re in essence making a food and mud puddle and then covering that with the rest of the dry soil. By doing this, you’re ensuring that the host of natural bacteria that resides in your soil can reach all of your food waste.
Once you’ve finished filling in your hole, it’s time to wait. I dropped some mulch over top of my bokashi burial site, mostly to be able to identify the exact area where I’d buried the bokashi later, and then left it alone.
How Long Does It Take For Pre-Compost To Become Compost?
Four days after burying my pre-compost, I discovered a few thin sprouts popping up from where the bokashi had been buried. I pulled aside the mulch and poked around with a shovel for a moment. I was surprised to find that no matter how far I dug down, I couldn’t find any of that material that I’d put in there four days earlier. There were sprouts, yes, and I’m guessing that they were from the cantaloupe seeds that I’d put in my bokashi bin. But other than those, there wasn’t a whole lot left.
I removed the mulch over the area and actually dug it up a bit more. After some digging around, this is all I could find that remained. You can see one remnant of something greenish. I’m guessing it was a bit of onion skin that hadn’t deteriorated as rapidly as the rest. There were a few sprouts and a very light dusting of whitish mold in one area where the pre-compost had been spread a little thicker than the rest. Otherwise, the rest of the bokashi had completely disappeared within four days. It left behind darker, nutrient-enriched soil.
My bokashi had fermented for about a month without being touched before I buried it. It’s entirely possible that the longer fermentation period made the pre-compost break down in the soil faster than normal, but I do have to admit that I was startled by just how fast it vanished away.
The bokashi burial process can take anywhere from the quick four-day period that I experienced to a more common average of a couple of weeks. If you have bones in your bokashi pre-compost, those may also be around for longer. But as a general rule, most fruit or vegetable waste, bread or pasta or rice scraps, and even most meat and dairy products should break down within a couple of weeks’ time.
Final Thoughts On The Bokashi Process
Overall, my experience with bokashi has been incredibly positive. I’m keeping my food wastes out of the landfill and putting them to work in my garden instead. I’m slowly improving the quality of the soil in my garden beds, too. Other than initially building the bucket and occasionally burying a batch, the process takes no extra time. In fact, it’s actually a lot less work than turning a traditional compost pile!
If you’ve been considering bokashi composting, I can highly recommend it. It might not be for everyone, but it’s definitely something I plan on doing for a long time. It isn’t replacing my tumbler composter or my stationary composter, but it’s yet another option for enriching my soil and improving my garden.