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The A To Z Of Bokashi Composting

The A To Z Of Bokashi Composting

19 minute read

Here is our A-to-Z guide on Bokashi Composting which should help you to take up this new process with ease . . . 

Did you know that ‘Bokashi’ is a Japanese word meaning ‘fermented organic matter’ and is a relative newcomer to the gardening encyclopaedia as it was developed in the early 1980’s!
Dr Teuro Higa, a professor at the University of Ryukyus, Okinawa, Japan, conceived the idea of beneficial micro-organisms as a way of replenishing the goodness in soils that had been over worked or treated with artificial fertilisers.
Since then this composting process has become more popular as it enables us to turn our kitchen waste into a useful household cleaner, plant fertiliser and soil enhancer. 

An anaerobic process, the Bokashi composting process takes place in the absence of air – unlike traditional composting processes which rely on the presence of oxygen or air to take place effectively. Rather than relying on air being present, Bokashi requires the use of an inoculated bran to ferment your kitchen waste (which can include meat and dairy) into a useful soil builder for your garden and a nutrient rich fertiliser for your plants, or strong drain clear. 

Strewing bran (also known as Bokashi bran) is a vital component in Bokashi composting, as you should mix it into your kitchen waste before adding it to your bokashi bin and pressing down on the waste to remove as much air as possible as the waste is compressed. 

You should cover the layer of waste with a handful of bran prior to sealing up the compost bin and leaving until it’s time to ad waste again.

This bran is a mix of bran meal, molasses, and beneficial microbes (inoculated into the bran) that flourish in anaerobic, acidic environments. It is the micro-organisms within the bran that initiate the fermentation process and prevents the waste in the bin from rotting. 

bokashi bran

Chop / Compress
When adding waste into your Bokashi bin you want to add as little air as possible. You can reduce the air you add by carrying out two simple steps: 

Compress waste in your bokashi bin

chop up chunky waste – such as cabbage stalks for example) – so they don’t dorm pockets of air around then

compress the waste you’ve just added – often a ‘mashing’ tool is included with a Bokashi kit, if not you can just use a potato masher – squeezing out any pockets of air. 

During the fermentation process there are no unpleasant odours of rotting waste – even when you remove the lid from the bin. Although when you remove the bin lid there will be some odour, it should not smell foul and if it does then you know something has gone wrong! You should be adding waste into the bin every day, ideally a layer 3 to 4cm thick and covering the whole surface of the previous layer.

Unlike many composting processes, using a Bokashi bin allows you to recycle lots of scrap foods which otherwise would be thrown away – this includes dairy products, such as cheese, yoghurt, sour cream, butter but not liquids, such as milk.

Other foods which you can add to your bokashi bin include cooked or dry pasta and rice, fish, meat, seafood shells (including shrimps – although ideally you should dry them out a bit before adding them to the bokashi mix and add a little more bran to stop them from smelling), and the by-products of food such as chicken bones, egg shells etc. Avoid putting in too much salty food, as too much salt is not good for your soil, so only add small quantities to the bin.

Effective Microbes – EM
Effective microorganisms are at the foundation of Bokashi composting and are found in the bran which you add to your Bokashi bin. A mixture of bran, molasses, water and EM-1.

It was Dr Higa, a professor at the College of Agriculture, University of the Ryukyus, Okinawa, Japan who decided to study microbial combinations in the 1960’s. All the organisms he put together shared three features, they were:

• non-pathogenic – they do not cause disease, harm or death to other organisms (so will not rot your scraps)

• anaerobic – this means they can thrive in environments where there is little or no oxygen

• facultative – means they are able to tolerate aerobic conditions (so can exist in both environments with air or without air).

One of the combinations which he created was tested on grass which showed very good growth as a result – this combination became the foundation for EM-1. 

The main aim of the Bokashi process is to enable your kitchen waste to ferment – so the airtight bin, the strewing bran you add and the way in which the bran and waste is added all combine so that fermentation takes place rather than decay.

During the fermentation process there are no unpleasant odours of rotting waste – even when you remove the lid from the bin.

Although when you remove the bin lid there will be some odour, it should not smell foul and if it does then you know something has gone wrong!

fermentation in the bokashi bin

So, if there is a foul odour you can sometimes right the situation by adding more bran. If this doesn’t work, it’s a case of emptying and washing the bin and starting again.

What you should remember, is that when the waste is fermented (sometimes referred to as pickled) the food scraps which have been added will look very similar to when you added them, so you will still be able to see carrot peelings, slices of apple etc etc. This fermented solid waste will then need further time to become a useful addition to your garden soil – this extra time can be achieved by adding it to a traditional compost bin or pile or digging it into the garden soil and leaving it at least 2 weeks before planting in that area.

During the fermentation process you might see mould in your Bokashi bin. If the mould is white then that is a good sign, if it’s black, blue or green mould then that is a sign that something is going wrong.

White mould is a fungi and when it appears on the surface of the waste it indicates that fermentation is taking place – so everything is going to plan to result in usable Bokashi compost.

However, when darker, coloured moulds appear this is a sign of rotting and putrefaction – so something has gone wrong in the Bokashi bin. There are a few reasons which can cause the process to fail – all of which are easy to solve:

• the bokashi bin is not airtight – you may not be closing the lid tightly enough, there might be a crack I the bin or the tap at the base of the bin may not have been closed tightly enough

• not enough bran is being added – every time you add new waste to the Bokashi bin you should add about 20ml of bran, sprinkled evenly over the layer of waste. Use more bran when adding dairy, bones or meat

• the Bokashi bran is no longer active – Bokashi bran has a shelf life of 18 months and should be stored in an airtight container, out of direct sunlight, at room temperature and kept dry. If the bran is old or has not been stored correctly than the microbes within the bran may be killed or weakened and then the bran will no longer be useful.

If there is only a small amount of coloured mould on the Bokashi compost you may be able to save the compost by adding a about 40ml of bran, closing the lid and leaving for two days. If the bran has worked the coloured mould will have been destroyed.

If not, then you need to dispose of the contents and start again. 


Indoor composting sounds like it would be a messy, smelly process but Bokashi bins have been designed in such a way that they are not only attractive – smart enough to be kept in your kitchen – they are also odour free – you’ll only notice the fermentation smell when you remove the airtight lid to add further waste.

Plus, there will be no worms or creepy crawlies just micro-organisms making their was through your waste.

Bokashi composting is a clever Japanese system that ‘pickles’ or ‘ferments’ your kitchen waste into a liquid feed for your plants, a strong disinfectant for your drains and a nutritious soil enhancer.

One of the benefits of this method of composting is that it takes up very little space – all you need are two Bokashi bins (two, so you can have a continuous composting process – once one bin is full you can fill the second. When the second is full it will be time to empty the first and start again). These bins are compact so will take up very little space and with so many attractive designs to choose from you will find one which compliments the style of your kitchen.

The Bokashi Organko Two bin is the next-generation in kitchen composting!

It's stylish design means it can be left on a kitchen worksurface - in perfect reach when you need to add any food scraps.

Because the Bokashi process involves fermentation rather than rotting, there are no foul odours and insects are not attracted to the bin so it's the perfect way to recycle your kitchen waste indoors.  

attractive bokashi bin for use in your kitchen

Kitchen composters have become increasingly popular as more and more people look to have a greener lifestyle.

A kitchen compost bin can be something as simple as a caddy into which you can add your food scraps and when full empty into your compost bin in your garden – making composting more convenient as you’re not having to take your food scraps to your compost bin every day.

Or they can be the more sophisticated units into which you add your veg peelings etc together with additional ingredients – such as Bokashi bran – to kickstart the composting process by fermenting your kitchen scraps.

During the Bokashi composting process the leachate that is produced should be drawn off. This is made easy for you as the majority of Bokashi bins will incorporate a tap, low down on the bin, which will make it quick for you to drain the liquid from the bin – ideally this should be done every 48 hours. This liquid should not but stored but should be used within a day or so.

Compress waste in your bokashi bin

If diluted in water, it can be used as a plant fertiliser – but it is very strong so should only be used in a very diluted form.

For watering plants once a week or less use a dilution rate of 1:100 or for plants watered daily use a dilution rate of 1:200.

Or, used at its full strength, it can be used to control slime and harmful bacteria in drains, pipes, and septic systems.

Minimum Maintenance
Minimum maintenance is required when it comes to your Bokashi bin. All you need to do, every time you empty the full bin of fermented waste, is to rinse the bin, lid and tap under running water – don’t add any cleaning agents, just use water on its own.

To ensure the tap is clean pour water into the bin with the tap closed and then open the tap to drain the bin – once the water coming out through the tap appears clear the tap is clean. That’s all the maintenance required.

The nutrient value of the materials - solid and liquid - produced by Bokashi Composting are amongst the highest of any composting process and are produced in a very short time compared to other composting methods.

The liquid product, often referred to as ‘Bokashi Tea’, makes an excellent fertiliser for feeding your plants directly – however you must remember that it needs to be diluted as it is so strong when neat from your Bokashi bin – a dilution rate of 1:200 is recommended.

The solid material left after Bokashi Composting can be used as a ‘fuel’ for other forms of composting – so you can add it to your conventional compost bin and it will decompose much faster as it has already been fermented. Or this fermented material can be dug into your garden soil – but it needs to be dug in where you have no plants as it is so rich it could damage plant roots if it came into contact with them as soon as being emptied from the Bokashi bin. After being in your soil for at least two weeks it is then safe to plant into the soil and let your plants take advantage of the high level of nutrients. 

It's possible to use a Bokashi bin in your kitchen as, unlike traditional composting where there will be the odour associated with rotting materials, there is no unpleasant odour with the fermenting process occurring inside the bin – even when you remove the lid to add more waste.

The waste in your Bokashi bin ferments rather than rots due to two main features of the Bokashi process:

• the Bokashi bins are airtight containers that prevent the inflow of air

• the Bokashi bran with its effective microorganisms which you add every time you add waste to the bin.

The pH of newly fermented Bokashi pre-compost is very low (approx. 3-4) as it is acidic, with this acidity ensuring there are no fruit flies, rodents, or pathogens in this pre-compost.

However, most plants prefer a neutral or slightly acidic soil (pH 5.5-7), will the ideal pH being 6-6.5, so you might be wondering if adding this Bokashi pre-compost to your soil will prevent your plants from thriving as the acidity is increase. In the short term the pH will be increased, but once dug into your soil it only takes 7-10 days for the pH to neutralise (neutral pH is around 7).

Using a Bokashi bin to turn your kitchen waste into a nutrient rich addition for your garden soil takes half the time it would in a traditional compost bin – so this quick fermentation process results in a quicker turn around with minimum effort.

Typically, it takes just a couple of weeks in your Bokashi bin with bran, for your waste to have been ‘pickled’ and ready to use.

So even though it will not look as though it has composted, you can now add the waste to your compost bin or dig it into your garden soil and it will break down amazingly quickly.

empty fermented waste into your compost pile

By adding the waste in this way, you will also be adding lots of beneficial micro-organisms into your garden where they will help improve your soil’s health and fertility.   


One of the simplest ways to turn your kitchen waste into a nutrient rich fertiliser in your garden, the Bokashi process is extremely straight forward.

add kitchen waste once a day

• Once a day add your kitchen waster to together with Bokashi bran into the bin – compressing the waste to remove as much air as possible before closing the lid.

• Once you have completely filled the bin with waste cover it tightly and leave to ‘ferment’ for the next 10-14 days.

• It is now ready to use . . . simple! 

Twin bins are the answer for a super-efficient Bokashi waste processing system. It allows you to fill one bin with waste, adding waste daily until the bin is full. This first bin should then be left (just draining off the liquid every day) for two weeks. During these two weeks you can start adding new waste to the second Bokashi bin.

After two weeks have passed you can empty the fermented waste from the bin and use as required.

Give it a quick wash in clear water and its ready to use again . . . this could be the same time as your second Bokashi bin is full, or you may have to wait until you have filled the second bin before moving back to the first bin.

twin bokashi bins

In this way you never have to waste any of your kitchen scraps, and you have a continuous waste processing system in place.   

One your Bokashi bin has sat full for up to two weeks, it’s time to take out your fermented kitchen waste and make use of it in your garden. There are two possible choices at this point:

Dig the fermented waste into your garden

When the waste is first emptied from your Bokashi bin it will be very acidic, so much so that it could damage your plants in their roots were to some into contact with this new waste – so dig it into your garden soil where you have no plants and leave it for a further 2 weeks at least – ideally four weeks – before adding any plants.

dig into your soil

This makes this ‘pre-compost’ ideal for use at an allotment where this powerhouse of nutrients will be appreciated by your plants yet still have time to settle into your soil prior to planting. 

add to your compost bin

Add the waste to your compost bin 

You might ask though ‘why not add it to the compost bin at the start and miss out the bokashi process?’

By adding your kitchen waste to a Bokashi bin and putting it through the fermenting process, when you then add the waste to your normal compost bin, you will save lots of time!! 

The 2-4 weeks spent filling the bin and leaving it to stand, will mean it only needs a month in your compost bin to be ready to use, unlike the months and months it normally takes for waste to decompose in a traditional bin.

Bokashi compost is ideal when you are growing vegetables as you can dig the compost into your soil to a depth to suit the vegetables you are growing.

If you’re growing rows of beans, then spread the Bokashi compost in the base of the trench you have dug – usually the trench would be 10-12 inches deep – then cover with soil.

For vegetable beds you can spread the Bokashi compost evenly over the surface of the soil and then cover over with soil and leave for a couple of weeks before planting.

If you are filling containers, add soil first to fill up one third of the container. Add a layer of Bokashi compost so the container is two thirds full, then thoroughly mix the two layers together. Then top off the container with soil or compost. Now leave for at least two weeks, ideally four weeks, then mix up the compost in the container again, if you can still see Bokashi compost then leave it for another week and try again. Or if no Bokashi compost can be seen you are ready to start planting.

What can you add to your Bokashi bin? Here is a list of items which will successfully ferment within your Bokashi bin:
• fruit and vegetable scraps
• citrus and banana peels
• prepared food
• cooked and raw meat
• cheese
• fish
• yoghurt
• eggs
• smaller bones
• bread
• coffee grounds
• tea bags
• withered flowers
• small amount of tissues   

What cannot be added to your Bokashi bin?
• liquids – this includes water, oil, milk, juice, vinegar
• paper
• larger bones
• ashes
• animal faeces

Quite a few of the items which you can add on the Bokashi process could not be added to a traditional compost bin - which means for maximum recycling and benefits for your garden, you would be best to combine a traditional compost bin in your garden or at your allotment with a Bokashi bin in your kitchen or utility room.


The Effective Microorganisms (Ems) in the bran used when carrying out Bokashi Composting are a set of three powerful microbes:
• Lactobacillus bacteria
• Phototropic bacteria
• Yeast
The yeast present in the bran is one of the reasons that if you remove the lid on your Bokashi bin it may smell like beer.

Zing Bokashi
We’ve had to go as far as New Zealand to find a ‘z’ work which relates to Bokashi . . . ZingBokashi is a two-bucket composting system where one bucket has holes and fits inside the outer bucket. The holes allow the liquids to drain into the outer bucket ready to be drained off.

Unfortunately, this system only seems to be available in New Zealand, are UK equivalent would be the Bokashi Organko Two Kitchen Composter.

The Bokashi Organko Two system is super streamline in design. Its outer container is smart enough to be left out on your kitchen work surface – you really wouldn’t know it was a composter! The inner container catches the solid waste whilst allowing the liquid to drain through the holes in the base, allowing you to easily drain the liquid every 48 hours.

This ‘Bokashi Tea’ is strong enough to be used as a drain cleaner or if diluted 1:200 it makes the perfect, nutrient rich fertiliser for your plants. 

Bokashi Organko Two

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