Make your own “soil factory”!


…and as you can see, it’s not in the least complicated!

This is a great way of putting your fermented Bokashi to use without having to dig holes or mess around with compost. Best of all, it’s really quick and easy and you won’t get your hands, clothes or shoes dirty.

You’ll need a plastic storage box of some kind with or without a lid (although it’s important that the lid isn’t airtight; a soil factory needs to breathe!). A plastic boat scoop like I’ve got here is also good to have.

Put a couple of scoops of plain old garden soil in the bottom of the box. Or some leftover potting mix. Or the remnants of a pot plant or tired soil from a planting container. Tip in a bucket of fermented Bokashi food from your kitchen. Add a bit more soil and mix and stir a bit so the food gets reasonably coated with soil. A top layer of say 10 cm of soil its good. Put the lid back on if you have one, loosely. Otherwise you can just throw over an old towel or a newspaper to help keep moisture in. Protect from rain or animals if necessary.

That’s it!

When you have a look in a couple of weeks you’ll see there’s more soil and less food. Your soil factory is doing its work! The nutrition and carbon in the Bokashi-treated food is being absorbed by the “start-soil” and what you end up with is “super soil”, an excellent soil improver to spread around your flower beds, use in planter boxes or outdoor pots, or sprinkle around plants that need a vitamin boost.

You can run your soil factory more or less forever. Just scoop out the soil you need for the garden and leave some in the box to mix with your next Bokashi bucket. If you have too much soil, you can start another box or scoop over some of the ready soil into black garbage sacks to use later — or give to your friends!

Some tips and ideas (and a couple of things to watch out for):

– You can “renovate” the soil from potplants that have had their day. Just add it to the box! This is also a good way of diluting the soil in your box and adding structure.

– Soil fresh from your soil factory may have a low pH for a week or two, depending on how long it’s been in the box. Experiment until you get used to it. It’s also extremely nutritious, so you might want to mix it with potting mix before planting in it.

– Chances are you’ll get some white mould forming on the top of the soil. GOOD! Just as it is in your Bokashi bucket, that’s a sign that the microbes are doing their work and colonising the soil. Mix it around if it bothers you, otherwise just leave it.

– Leaves are great! Toss a few handfuls of autumn leaves into your box and watch them disappear. They’re a good resource and good for the soil structure, handy if you don’t have enough garden soil to use in your box.

– Soil like this is nature’s own product. It will last forever! The sooner you get it onto your plants the sooner they can benefit from the nutrition and microlife in it, but otherwise it’s easily stored until spring or whenever you need it.

– Temperature. Warm is good! Not so hot you kill the microbes (keep it under 40 degrees C), and not so cold nothing happens (less than +6 degrees C). In a sunny spot by the kitchen door is good, on the balcony if you live in an apartment, in the cellar by the boiler if you have one. In the wood shed, the laundry, the garage. It will all work, just test and see what suits you best. And it doesn’t matter if your soil factory freezes, the microbes will come back to life again in the spring and carry on their work.

So good luck! And let us know how you get on with your soil factory!

45 thoughts on “Make your own “soil factory”!

  1. This is great for rural Alaska where outdoor winter composting is almost impossible, soil is often low in organic matter, and commercial soil ammendments are hard to find and extremely expensive. Thank you…

  2. The soil factory idea is fantastic. I have only one Bokashi bin, and I’m wondering how fast I can move my Bokashi waste from the bin to a tub with some soil? Anyone tried moving it sooner than 2 weeks? Otherwise maybe I need to make or buy another bin…

    1. Hi Annmarie. The best thing would be to get/make another Bokashi bin. The microbes really need those 2 weeks to do their thing, they reproduce every 20 minutes or so under the right conditions and it’s good to get a good colony going. Otherwise the risk is your food will start to rot.
      There’s a couple of suggestions on the blog how you can make your own, another one I haven’t written up yet is just to take a plain bucket with a TIGHT lid and put newspaper in the bottom (say 1 cm thick). Add serviettes, kitchen paper etc in the mix and top it off with another newspaper, give it all a good squash at the same time and you’ll fit quite a lot in. This works really well, and worms love the paper which also gets fermented.
      Good luck with it all!
      ps make sure you put your soil factory in a wam spot — but not too hot if you’re lucky enough to live in a warm place. Aim for soil temps between 20 and 40 degrees C. You don’t need the lid on if you think its too hot in there, a newspaper can be good to keep humidity under control.

      1. Thanks Jenny for the advice. Will make a new bin as suggested. (I reckon a nappy bucket might be good – they have tight lids…) No problem here with temperatures in Australian Summer. The soil factory will be nice and toasty. All further thoughts most welcome.

  3. Hello! I’m waiting for my two Bokashi bins to arrive and I’ll be composting for the first time. I live in Miami, Fl and don’t have a garden. I think I’m going to use this method. I wonder if I’m better keeping the bins with the fermented Bokashi indoors, because in the summer it’s extremely humid and gets to 35 degrees. Also, I worry that my dog will try to get into it outside.

    1. Hi! Nice to hear from you!
      Probably the best is just to test your way forwards and see what works best. Step 1, the bucket fermentation bit, is definitely best indoors in or near the kitchen. But step 2, the “soil factory” is dependent on heat to get going so you might want to try it somewhere warm but not in direct sunlight. Do you have access to dry leaves in the fall? If so they seem to be even better in a soil factory than soil to trigger the process. Collect up as many as you think you’ll need and layer them with the fermented bokashi in your soil factory.
      One extra thought: if it’s too humid in your soil factory chances are it will start to smell. Easily fixed, just throw in a newspaper or two to take up the moisture.
      You might want to check what the guys at Bokashi Dubai are doing, their climate is probably more like yours than ours is!
      Good luck! And get back to us with how you get on.

  4. I’ve got my ‘soil factory’ going on my balcony in London! Waiting for it to break down into a usable state. It’s been in the box for the last month… plenty of white mold, it seems to emit heat and condensation, and I think it is becoming less ‘foody’ and more ‘earthy’. It’s hard to actually scoop any out that isn’t just earth-coated chunks of food yet though. How much longer do you think it will take? I don’t have any land or garden access, so all i have is old potting mix to throw into the box, that I have used to grow plants in. Is this as good as ‘actual’ soil from, like, the earth? Might it be lacking in soil microbes? My box is translucent so I stare at it in fascination every day…

    1. Hi Zara — and good on you for having a go! Your “soil factory” will work out fine, it’s just a matter of time. And how long it will take really just depends on how warm it is in the soil. Hot and sunny on your balcony = faster rather than slower. Old potting mix is fine, you could toss in the plants as well if they’ve had their day. Outdoor soil is often faster because it has the right soil microbes but potting mix is probably better in the long run because what you’ll get is reinvigorated potting mix, better suited to potplants than plain soil. The more soil you have in the box the quicker the food will become soil. The less soil the stronger it will be nutrition-wise. But there’s no perfect recipe, just to find what works for you.
      If you think it’s too wet in there you could always throw in a newspaper to soak up the condensation, you’re looking for the sort of dampness you normally expect from soil. Not too wet, not too dry…. 🙂
      If you keep some of this soil behind to use in the next batch you’ll notice the difference as the soil is already sort of activated so it will go quicker.
      I have to admit I find it quite fascinating too to poke around and follow the process, nature is fantastic isn’t it?
      Good luck! And let us know how you get on!

  5. Hi! I’ve had a plastic container with fermented bokashi and top soil, dried leaves and newspaper going in a warm dark closet for about 5 weeks. It doesn’t appear to be breaking down, and it smells pretty bad. The smell is different from garbage, but not good. What do you think the problem is?

    1. Hi Paula! It sounds like a good mix you have going there so I’m sure it will work in due course. How long it takes depends entirely on temperature, a wardrobe is probably slower than in the sun but faster than a cellar. All very unscientific I’m afraid! The process has a low pH which means it can smell a bit sour until its done. Usually the reason for smell though is humidity. Is there any condensation inside the lid? You could always throw in a newspaper to take up the moisture. Or add some dried out potting mix, coconutt fibre or the like. But hang in! And let us know it goes, this is good information to help us all find new ways of making soil. Thanks for sharing…

  6. This is an old post, but still very helpful! Thank you very much for sharing your experiences and tips on Bokashi composting.

    I started my own soil factory in my garage a few weeks ago after reading this post in the Winter. I’ve noticed a LOT of condensation. Then yesterday the entire garage was smelly! I added lots of top soil then walked away. I’m glad I found this post again this time and read about what to do about all the moisture and smell. I just laid a couple layers of newspaper on top and hope it works. I can’t wait to harvest some of this nutritious soil.

    1. Hi Alexis! Hope it works for you now. There’s a good chance it will — condensation is our worst enemy. There’s nothing can make Bokashi stink like too much moisture! So just do whatever it takes to soak it up and hopefully, hopefully you’ll be fine!

  7. Hi Jenny, I just realize I made a big mistake when dumping the Bokashi pre-compost in my soil factory: I forgot to mix everything up with the soil! Here’s a detailed account of what happened and how I (hopefully) corrected it:

    Do you think my soil factory is ok? It smelled pretty bad but the pre-composted food didn’t look like it was rotting. It looked the same as it did right out of the bucket. Today the smell is pretty much done, and the top remained dry (as in the picture).

    1. Hi Alexis! Sounds like you’re almost on track. Bokashi is not hard (and as you say it will pretty much always work in the long run) but it can take a while until you crack the code. A simple trick like adding newspaper, who would have thought it would make such a difference??!!
      The timing factor is all a matter of temperature. While a garage is great for winter storage nothing much is going to happen in the cold. (And anything less than 15 degrees C is cold for microbes.) Assuming you have early summer wherever you are it may be warmer to move the soil factory out into the sun? Find the sunniest spot you can and let the heat do its work. Mid-summer you can expect soil in two or three weeks, spring and autumn it would probably take a few weeks longer. But if you then remove some ready soil to use on a project somewhere and add a new bucket of Bokashi to your soil factory you’ll probably find it goes a bit faster, the microbes will well and truly be up and running by then and will deal with the new bucket load quite efficiently. You could even skip the lid for a while and add a few worms, they’d love it in there. (You’d need to keep the rain out though so they don’t drown.)
      So good luck! Look forward to the next installment!!

  8. Hi Jenny, I thought I’d give an update on my Bokashi “mistake.” I checked on my soil factory one week after I mixed the old Bokashi’d food waste (which I buried in my soil factory last Winter). Everything has pretty much turned into soil! There are a few big clumps here and there, such as banana peels and chicken bones. Most of them are unrecognizable. I always panic when I’m digging up a chicken drumstick bone, because at first it looks like a finger, lol!

    So there you go. One week after I mixed the pre-compost with the soil, I have Bokashi compost. I’ve “harvested” some of the soil and used them in containers and in my flower garden.

    Now that it’s warm, I think I’m not making Bokashi fast enough!

    1. What a relief!!! Now you can start the fun part — I’ve just never seen anything grow as well as it does in Bokashi soil. Let us know how the next bit goes!!! /Jenny

  9. Hi Jenny,

    A couple of weeks ago, I started a soil factory with our bokashi. When I went out today and peeked inside, I noticed a lot of maggots in the bin. Is this normal? I tried to google but couldn’t really find any good answers.

    1. Hi Andrea. Yep, I’ve even managed to get maggots myself this summer, disgusting isn’t it? I think they turn up because flies have got hold of the food before it landed in the bin and laid their eggs which then become maggots. It seemed to me that the little critters were very keen to climb out of the bin when it was opened so it wasn’t their home of choice. In the end I resorted to wiping them off the bin walls with a wet paper towel, apart from being icky I don’t really think it’s such a serious problem.
      What did you do about yours?

  10. Thanks for the information! This is our first soil factory so we’re still figuring out what we are doing. Right now, we haven’t done anything about the maggots. They weren’t trying to climb out when I looked in the other day, so I just shut the lid and left them alone. We’ll have to check them again and see if they’re turning into flies yet.

  11. Would it be ok to use regular potting mix (as i have an extra bag lying around) instead of garden soil as the base foir the mix in the soil factory? And as for the soil factory container, there shouldnt be any holes correct? Would this be the correct layout: a 20 gallon rubbermaid tote with lid, first layer is potting mix, then cured bokashi waste, then another layer of potting mix. Can I also sprinkle some bokashi bran on the topmost layer? Thank you!

    1. Hi Licelle! Absolutely. Use the potting mix if you have it lying around. It’s also a good place to tip any old pot plants that have seen their better days, the soil will become like new again.
      The soil factory works best if you have no holes, but watch out for condensation. If there’s droplets/mist on the inside of the lid or on the walls it’s probably a bit damp and may start to smell a bit sour. Add a newspaper or something else dry to take up the moisture, it’s easily fixed.
      Your layering sounds perfect to me! By all means add a bit of extra bran if you want but there are so many microbes at work in the cured Bokashi it shouldn’t be necessary to add more bran.
      Good luck! Hope it goes well for you!

  12. It is hot and humid now in Tokyo! 34C and 90% humidity, and I have to say that my bokashi bin is not nice!!! Stinks in fact. Not rotting food exactly, but more like vomit!!! I have decided to put my garbage directly into the compost bin until the end of September. One advantage of this is I can also compost my ‘browns’ — I have found that this is a disadvantage of the bokashi method, not being able to compost paper etc in the same container. Do other people save up their browns and add them at the end?
    I have had three lots of cured bokashi now, and buried them in containers in the garden. They very quickly composted down, and I have amaranth growing in the containers now. What I have noticed is that over time it rots down even more — the level in my containers has dropped a lot. When I get my next lot in the autumn, I think I will put it in a container in the usual way, and then put another layer of cured stuff on top of that a month later.
    Doesn’t the soil factory smell sort of musty?

    1. Hi Elisabeth. Ick, a stinking Bokashi bin is not fun. Nearly always it happens when there’s too much moisture in the bin. The simple solution is to just add a newspaper — if the newspaper gets really wet you can switch it for another one. There’s nothing to stop you putting paper in a bokashi bin although most people don’t as they want to get as much of the liquid as possible. As far as your standard compost bin goes, it makes good sense to alternate bokashi with browns (paper, dry leaves, sawdust etc), I usually suggest people take a bag of paper scraps with them from the kitchen when they go out to empty a bokashi bin in the compost. It also helps keep flies off the bokashi, should that happen to be a problem, if you put the paper on top.
      This idea with a soil factory is far from perfect, if you can bury bokashi down directly that’s always a better option. But sometimes that’s not possible and a plastic box or barrel with lid is better than nothing. As always with bokashi, the warmer the better — if you can get it out in the sun it will become soil faster. (Unless you live in a really hot place! Max 40 degrees in the soil is a good guide, the microbes will conk out otherwise)
      And yes — the volume does decrease when the soil takes up the bokashi food waste and the liquid dissipates. The plants probably use up a bit of it as well. Just as well the volume does decrease though — gives you space to add more bokashi to the container!
      Good luck there! /Jenny

  13. I have maggots in my soil factory and I cannot get them out. Should I leave things as they are? What do I do when I want to use the soil? Just use it maggots and all? Help!

    1. Yuuckk!! I can sympathise with that Lina, I had them once. Very unpleasant, but apart from being revolting I don’t think they do so much damage. Could be that some flies got to your food waste before it got into the Bokashi bin or at some other stage in the process and laid their eggs. And now they’ve turned into maggots… I’m not convinced they really like the acidic atmosphere in a bokashi bucket/soil factory, from what I’ve seen if they can get away they will. Depends of course on where your soil factory is, but would it be possible to leave the cover off for a bit and see if they crawl away? Or move the soil away in bucket-loads to a quarantine area where they could escape in peace?
      I’m no expert on this subject so if there’s anyone out there better experienced it would be great to hear what you think.
      Good luck though!

  14. There are ‘good’ maggots, you know! The maggots of the black soldier fly chomp through garbage like there’s no tomorrow, leaving behind maggot castings, I presume. Most years they arrive in my traditional compost container. The first year they came, I was absolutely grossed out, opening the bin and seeing a seething mass, but over the years we got used to them, and my sons would inquire every summer if my ‘pets’ had arrived yet. The problem is that they reduce the volume amazingly, which is what we don’t want with bokashi. I never had clouds of flies hatching out, which really surprised me. Have a look at this!

    I got lots of other hits on google!

    1. Thank you, Jenny and Elisabeth. I buried the almost ready soil (the food scraps had not fully turned onto soil yet) in various parts of the garden. I hope my plants get a good nutrient boost but at the same time I am worried the maggots will destroy my plants. So far the plants are all still alive :).

      1. I think maggots thrive on dead or decaying matter, so your plants should be fine! Have you seen the treatment using maggots to clean out necrotic wounds? Perfectly gross to look at, but how amazing!

  15. hi jenny, does can you use any sort of airtight plastic container for this process? I have some round food containers from a restaurant that had feta cheese stored in it. Unlike your tub it doesn’t let any light in…is this a problem?…thanks Trish

  16. Any container will work Trish, it doesn’t have to be especially airtight (or even have a lid) as long as you have soil as the top layer. It’s kind of like a hole in the ground really. Better not to have any light in actually. If you want the process to go faster you can put a black plastic bag over it to increase the heat, depending on what climate you live in of course. Good luck!

  17. I am using this method to create soil and knew heat was beneficial but didn’t realise that 40 degrees was the limit (and it has been in the low to mid 40s here, hot hot hot!). It has been over a month and there is still quite a bit of waste to be transformed. If I have killed the microbes, is there any way of bringing new microbes in to continue the process? Our growing season will start in a few weeks and can’t wait to use the supersoil! Thanks!

    1. Ah, I think you’ll be fine. It’s probably not that hot in the middle of the bucket or barrel or whatever you’re using. Stick a thermometer in and see what the story is. Otherwise you could maybe put it in the shade or something? Probably enough of the microbes will survive and because there’s so much nutrition in the soil factory they will restore their community pretty fast as soon as they’re happier about the climate. So no worries, I would say…

  18. I am using this method to compost my bokashi bin contents as I have no garden to bury it in, only a patio. However, I though heat was good and didn’t realise temperatures over 40 C would kill the microbes. It has consistently been in the low to mid 40s C here since I started this about 6 weeks ago and there is still quite a large amount of waste to be broken down. Is there any way to restore the microbes and continue this process? Our growing season starts in a few weeks and would love to use some great homemade soil if possible. Thanks!

    1. Hi! That’s a hot place you’re living there! Maybe you could stick a thermometer in the soil and see how warm it actually is in the soil (there are special soil thermometers but a kitchen one will do). Soil normally takes a fair while to heat up so no worries, but if you’ve got smallish pots in the sun it could well be pretty warm in there.
      Are you using a bokashi bin with tap? If so, you could recharge the microbes in your pots by treating them to some bokashi juice when it cools down. You’ll have all the nutrition you need obviously from the original bokashi you dug down. It’s impossible to know how well microbes are doing in the soil, as long as some are ok (which they’re sure to be) they will reproduce quite quickly and give you a full quota in no time. You could even speed things up by dosing with EM in some form (no nutrients but a lot of microbes) or add extra bokashi bran directly to the soil.
      If it seems the bokashi is taking a while to break down, you could consider mixing it with soil in the pots. Maybe out the soil, stir it up and put it back. The more soil contact on the food waste the better, it’s the contact between the two microbe groups that do the trick of transforming the bokashi into soil. The smaller the food bits, the better, too. Technically speaking, it’s better not to mess around too much with microbes in the soil though, they like their peace and quiet like the rest of us (and adding oxygen to the process in this way will also release carbon gases to some extent). But a bit of mixing around will definitely speed up the process if that’s a consideration.
      Don’t worry about it too much, your soil will be great for planting in. In general, bokashi is really forgiving. Most things work, it’s hard to really make a mess of it.
      So good luck!

  19. Thanks for this post. I’ve sucessfully made a soil factory with my bokashu pre-compost. It’s turned into soil. The only thing is the soil has a very strong odour. Is this normal? Will airing it in an open flowerpot in sunlight help?

    1. Anita, I suspect it’s too wet in your soil factory, that’s usually what causes the smell. They generally tend to work better without a lid, soil needs to breathe (I need to check my post to make sure I’ve made this clear ;-)) Many people put an old towel or something over to keep the soil moist while allowing it to breathe. If your soil factory is outside in the rain you may need to come up with another plan, perhaps a stick or two between the lid and the tub to allow some air in while keeping out the rain?
      Without air the soil can tend to get a bit rotten and that’s what would be smelling. Leave it open to the air for a bit and it should come right. If it’s too wet in there then it will dry out. Put a newspaper on top as an alternative and replace it when it gets really damp.
      But you’re on the right track, your next one will be perfect!

  20. Jenny
    I’ve been doing bokashi for a while now. I too started a soil factory, having been disillusioned with the oft-repeated advice to dig the preserve into a trench. Great in theory, but what about established plants, or rock hard soil in winter, or … etc.?

    Unlike yours here, my factory is still in the soil, but it occupies a small area of bed, which rotates from time to time. My current factory will soon grow rhubarb. My previous one is about to get potatoes, the one before that is growing winter broad beans, and so on.

    A big upside of this – and my worry about your bin method – is that I’m feeding the soil ecosystem directly; the whole ecosystem, not just a bucketful or a few added worms. The by-products of the ecosystem as a whole are, in the end, the only form of food that plants can take up.

    Worms are still the most visible and active component, because most else is too small to see. If I dug a forkful now I’d find usual species like lobworms plus some migrants like brandlings and tiger worms who come for the feast. One of my neighbours may have an empty wormery! And that’s the point – the last stage of bokashi direct to soil is effectively a wormery, for no extra cost or effort. With all the excreta and tunnelling, the soil quality is fantastic. I take whatever I need for top dressing elsewhere.

    I do have to protect the surface from worm-eaters like fox and badger. I use mulch under chicken wire. The mulch slowly turns into more soil food, keeping the activity going long after the bokashi is eaten. Your blog makes me wonder about a hybrid approach with half sunk, bottomless bins; wide-diameter pipes, perhaps?

    Keep up your inspiring work! I wonder if you’d be interested in what I’ve uncovered about the biochemistry of the bokashi bin. It is much misunderstood online, and numerous tips follow from it.

  21. Will I need to add worms to my soil factory just so it decomposes faster? If I do, will the procedure in making the soil factory differ? Any shredded paper like bond paper, carton, etc.
    can also be added to the soul factory ? I have a lot of paper and would like to put it to good use. Thanks!

    1. Why not test half with and half without worms?

      Pendng an answer from Jenny, my understanding is that, initially, the work is started by soil micro-organisms. Worms added at this stage would retreat from the bokashi ferment, until some of its lactic acid content has oxidised after a few days. (This can be observed by anyone who adds ferment to a worm bin, where the best advice is to put it in only a part of the area.) Worms might die if there’s nowhere to retreat to.

      The worms arrive as soon as there’s something fit to eat. It is reasonable to assume that they aren’t so much interested in the bokashi as in bacteria – their normal diet. They eat everything (soil, bokashi, bacteria) but only absorb the latter and excrete the rest as worm casts, which give us plant food and better soil structure.

      This is one reason why i prefer a factory in-soil to a plastic bin. The bin does not contain the full soil food web, from bacteria to predators, so much bokashi may decompose without leaving organic carbon in the web. Such a waste of your efforts! Personally, I rotate a small factory area around the garden beds every few buckets.

      Paper is best used as mulch. It reduces weeding and evaporation, and eventually the worms have it. But make sure it isn’t contaminated.

  22. I’ve been running a soil factory for some years now but have not been mixing the soil through the fresh Bokashi – will try this to see if it speeds the process. I have 2 compost bins – when one is full I start filling the second one, When this is full I empty the first one to top up my raised veg beds – its always full of roots at the bottom from our neighbour’s trees so it must be good!

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