Learn / Composting methods
Bokashi: ferment your kitchen waste, cooked food included.
Bokashi is a sealed-bucket method that ferments kitchen scraps instead of rotting them. It works indoors, takes almost no space, produces little smell, and handles cooked food that an ordinary compost heap can’t.
Fermentation, not composting
Ordinary composting needs air. Bokashi needs none. You pack scraps into a sealed bucket with a special bran, and the microbes in the bran pickle the waste. What comes out looks almost like what went in and smells sour, like pickles. It is not finished compost. It is a pre-compost that you finish in the soil or in a compost heap.
How bokashi differs from composting
| Bokashi | Ordinary composting | |
|---|---|---|
| Process | Fermentation without air, using bran full of helpful microbes. | Decomposition with air. |
| What goes in | Fruit and vegetable scraps, cooked food, dairy, meat and small bones. | Mostly plant waste. Meat, dairy and grease are discouraged. |
| Browns and greens | No balancing needed. | Needs a balance of browns and greens. |
| Where | Indoors, year-round, in a very small space. | Outdoors, with more room. |
| Speed | About 2 weeks to ferment, then 2 to 4 weeks in the soil. | Weeks to months, depending on the method. |
| Result | A pre-compost that must be finished in soil or a compost heap. | Finished compost. |
SOURCES: NC STATE EXTENSION, “BOKASHI COMPOSTING: A FASTER, EASIER WAY TO TURN KITCHEN SCRAPS INTO GARDEN GOLD”; WSU EXTENSION KITSAP, “BOKASHI COMPOSTING”
A bucket, a lid and bokashi bran
The bucket
Use a bucket with a tight-fitting lid. A simple two-bucket system works well: drill several holes in the bottom of one bucket, put the lid on it, and stand it inside a second bucket that collects the liquid that drains out.
The lid must seal well, because the process only works without air.
The bran
Bokashi bran is wheat bran or rice hulls that have been treated with lactic acid bacteria, yeasts and photosynthetic bacteria. It is the engine of the whole method. You can buy it ready-made or make your own.
Making your own bran
A recipe from the Kokuā Hawaiʻi Foundation uses these quantities. Keep the same ratios to make more.
- Bran: about 1.1 kg of wheat bran or pollard (the source uses wheat mill run). Rice bran also works.
- Water: about 600 ml.
- Microbes: 1 tablespoon (about 15 ml) of EM-1 (effective microorganisms).
- Molasses: 1 tablespoon (about 15 ml).
- MixMix everything thoroughly in a tub.
- Squeeze testSqueeze a handful into a ball. It should hold its shape but crumble slowly. If it is too wet, add more bran.
- Seal and fermentPack it into an airtight bag or container, pressing out as much air as you can. Leave it for about two weeks. It is ready when it smells sweetly fermented.
- Dry and storeSpread unused bran out to dry in the sun, then store it in an airtight container.
EM-1 is sold through our sister shop, Shamba Mtaani.
SOURCES: KOKUĀ HAWAIʻI FOUNDATION, BOKASHI RESOURCE (2019); WSU EXTENSION KITSAP
Step by step
- Chop your scrapsCut large pieces into smaller ones. They ferment faster.
- Add scraps, then branPut a layer of scraps in the bucket and sprinkle a handful of bran over it. Repeat each time you add food. More bran is safer than less, especially when you’re starting out.
- Press down and sealPress the waste down firmly to push out air, then close the lid tightly. Open it only briefly and only when you need to add more.
- Drain the liquidEvery few days, drain off the liquid (“bokashi tea”) from the bottom bucket. Drain it daily if the contents are very wet or smelly. Avoid adding soups, sauces or other free liquids.
- FermentOnce the bucket is full, close it and leave it for about two weeks in a spot that is not too hot or cold. The food will still look much as it did. That is normal.
- Bury it or add it to a compost heapSee below. Don’t use it as a surface mulch and don’t plant straight into it.
Using the liquid.
Dilute it heavily before use. One source suggests about 1 teaspoon per 4 litres of water, used straight away on the soil at the base of plants or trees. Don’t pour it neat, and don’t store it.
Finishing it in the soil
Fermented bokashi must finish breaking down before roots reach it. There are three good ways to do that.
- Bury it in the garden. Dig a trench or hole 20 to 30 cm deep. Add a layer of fermented waste about 2.5 to 5 cm thick, mix it with at least two to three times its volume of soil, and cover it fully. Wait about 2 weeks before planting in warm, active soil, or 3 to 4 weeks in cool or compacted soil. For pots and containers, wait 4 weeks or more.
- Use a holding bin. Mix 1 part bokashi with 3 parts soil in a spare bin, keep it moist but not wet, and leave it for 3 to 6 weeks.
- Add it to a compost heap. Treat it as a green input. Bury it in the middle of the heap and balance it with plenty of browns. See heap composting.
Around trees and shrubs.
Dig 25 to 30 cm deep, outside the drip line. Never place it against the trunk or roots.
SOURCES: WSU EXTENSION KITSAP; NC STATE EXTENSION. DEPTHS CONVERTED FROM INCHES.
What to look for and how to fix it
| What you see or smell | What it means | What to do |
|---|---|---|
| Sour, tangy, pickled smell | Good. It is fermenting as it should. | Carry on. |
| White mould | Healthy and expected. | Nothing. |
| Rotten, putrid or ammonia smell | Not fermenting properly, usually too little bran or too much liquid. | Add a generous layer of bran, press down firmly, drain daily, and chop scraps smaller. |
| Green, blue or black mould | Competing fungi, usually because air got in. | Remove affected material if there’s a lot of it, add extra bran, and press down. If mould dominates, discard the contents and restart. |
| Fruit flies | Air is getting in. | Add bran after every addition, wipe the lid and rim, and check the seal. |
| Bin swells or hisses | Gas from fermentation. | Vent briefly. It is harmless if it still smells sour. |
| Food still looks fresh | Normal for bokashi. | Judge by smell, white mould and softer texture instead. |
| Weak fermentation | Not enough bran, or the bran has gone off. | Use more bran per layer. Replace it if it smells musty. |
SOURCE: WSU EXTENSION KITSAP
Questions people ask
Is bokashi finished compost?
No. It is fermented waste that needs a few more weeks in soil or in a compost heap before it is safe around roots.
Can I really put cooked food, meat and dairy in?
Yes. That is one of bokashi’s main advantages over a heap or bin. Keep the lid sealed, and avoid very wet foods such as soups and sauces.
Will it smell?
A working bucket smells sour or pickled. A rotten or ammonia smell means something is wrong. Add more bran and drain the liquid.
Do I have to use bran?
Yes. The bran carries the microbes that make the method work. Use ready-made bran or make your own.
I don’t have a garden. What do I do with it?
Mix it with soil in a spare bin or large pot and leave it for several weeks, or give it to a neighbour or a farm that can bury it.
Want to see a bokashi bucket working?
We train households, schools and institutions to handle kitchen waste with bokashi, heaps and bins.