How to make a simple soil factory

Nutrient and microbe rich bokashi compost

What is a soil factory?

A soil factory is a place where you produce high quality nutrient rich soil. It’s your go-to place for compost and potting soils. It’s just like your bag of shop-bought compost but it’s home made and you know exactly what has gone into it!

How will a soil factory help in my garden?

A soil factory provides a great place to put your bokashi pre-compost throughout the year but can be especially useful during the winter and summer months. During the winter my ground is often too frozen and hard to dig a trench to bury my pre-compost. My soil factory provides a great place to put my pre-compost and serves as a great source of fantastic compost when spring comes around. During the summer months I like to use every possible space to grow fruits, veggies and flowers and it can be hard to find a spot to bury my pre-compost. So, once again, I turn to my soil factory for my bokashi pre-compost. I then simply go back to my soil factory whenever I need compost. Its really just like a small, portable, low-maintenance compost pile.

How to make a soil factory?

Making a soil factory is easy. There are a number of different methods for making a soil factory. Below are three of the methods we have found to be successful (in no particular order); using a container, using two (or more) compost bays or burying in the ground.

Method 1: Using a container

This method works well if space is fairly limited or you only need a small amount of compost.

Step 3: Add a few inches of regular garden soil and mix slightly
Step 3: Add a few inches of regular garden soil and mix slightly

Step 1. Find container

Find yourself a large plastic box with a lid. Drill a few holes in the bottom to let liquids escape. If your soil factory will be positioned on impermeable ground (such as a patio, garage or balcony), then do not drill holes in the bottom.

Step 2: Add garden soil

Next, put 3-4 inches of regular garden soil at the bottom of the container. *Tip* Try to use healthy soil with lots of life in it. The more worms and grubs the better!

Step 3: Add your bokashi pre-compost

Then you are ready to add your bokashi pre-compost. Empty the contents of your fermented bokashi kitchen composter to the container, making sure to break up any large lumps of pre-compost. Add another couple of inches of regular garden soil and mix slightly with a garden shovel.

Step 4: Add more garden soil

Add a few more inches of regular garden soil and place the lid on the container. The final mix of soil : bokashi pre-compost : soil should be about a third, a third, a third. The depth of each will obviously depend on the size and dimensions of your soil factory.

Put a couple of stones on the lid to weigh it down, if needed.

Step 5: Wait

Leave for 2-4 weeks and check your soil factory. It may take slightly longer for your pre-compost to break down in your soil factory than when using the trench method as there are fewer worms and other soil biota in your soil factory. Colder temperatures may also slow down the process too. You can speed the process up by mixing the contents of your soil factory every week or so. Be patient, the pre-compost will break down and you will have a soil factory full of great compost.

Step 6: Use compost or add more pre-compost

Feel free to add more pre-compost to the top of your soil factory. Remember to mix the contents each time after adding. Remove compost as needed. Remember, if you expect to need compost within 2-4 weeks, don’t add any fresh pre-compost to your soil factory. If you want a regular place to put your pre-compost and a place to constantly get compost then we would recommend setting up two soil factories.

Method 2: Using two (or more) compost bays

This is a great method if you have a small unused corner of your garden that you can set aside for your bokashi soil factory.

Compost pile

Step 1: Build a compost bay

This approach looks similar to a more traditional compost set-up. Build two, or three, boxes (similar to the one shown in the photo). The first box will contain garden soil, the second box will be used to layer your bokashi pre-compost and the third box (if using a third) will contain the finished compost.

These boxes should be covered to protect from the rain and should allow good airflow. The size of these boxes will depend on the amount of bokashi pre-compost your household produces and the amount of compost that you hope to create. They don’t need to be as large as a traditional compost pile as they will only be used for adding your bokashi’d food waste. 1 to 1.5 metre cubed boxes should be sufficient for most households.

Step 2: Collect garden soil

Collect some garden soil for the first box. You can add soil to this box whenever you have some old soil that needs a boost. For example, from planters and containers that need replanting.

Step 3: Add your bokashi pre-compost

Add your bokashi pre-compost to the second box. Then add a couple of inches of garden soil from the first box and mix well. Finally, add a couple more inches of garden soil from the first box.

Step 4: Repeat

Repeat steps 2 and 3 until your box is full. If you are using the three box method, you can then start layering the bokashi pre-compost and garden soil in the third box. If you are using the two box method, you should harvest your compost to make space in your box to add more bokashi pre-compost (see step 6).

Step 6: Harvesting your compost

If you are using the three bin method then harvesting your compost is simple. Once your second box is full, simply leave it for 2-4 weeks for the final bokashi pre-compost to break down. You are then ready to collect and use your finished compost as and when you need it.

If you are using the two box method. You will need to collect your finished compost from the bottom of your box. There are various ways that you can do this, but here are a few suggestions to get you started. (1) Design your box to allow access at the bottom of the box so that you can dig and remove the finished compost. (2) Don’t add bokashi pre-compost for a few weeks so that the most recent layer of bokashi pre-compost has time to fully break down. (3) Move the top layers of bokashi pre-compost to one side so that you can access the lower (finished) compost.

Method 3: Burying in the soil

Making a soil factory in the soil is really a combination of the above container soil factory and the regular trench method for burying your pre-compost.

Step 1: Choose an area 

Firstly, choose an area in your garden that you don’t need for planting in the coming months.

Step 2: Bury your pre-compost 

Next, use the trench method to bury your pre-compost. Rather than planting directly into this area, use this area for collecting compost to be used on the rest of your garden.

Step 3: Make a grid pattern

You can set up a grid pattern if the area is large enough. Add pre-compost in rotation to 3-4 areas in your soil factory area. This gives you a regular place to bury your pre-compost and a constant supply of compost. It also has the added benefit that you don’t need to plan your planting schedule around when your pre-compost will need to be buried.

Order now! Find all your bokashi composting supplies in our online shop.

You might also like to read

The importance of healthy soil

Bokashi composting: how to get started

17 thoughts on “How to make a simple soil factory

  1. Hi there!

    If the soil factory container was clear and left on a balcony, would that matter? Or does it need to be opaque?

    Thanks!

    Hannah 🙂

    1. Hi Hannah,

      Interesting question! Keeping the soil factory on your balcony should be fine as long as you can keep it out of direct sunlight to prevent it overheating and killing the life inside the soil. Ideally the container should be opaque to create an environment favored by soil biota (ie dark). You could simply place the container in a large black garbage bag or wrap it in newspaper, old carpet etc.

      I hope that helps. Feel free to ask any other questions here 🙂

      Nicki and the Bokashi Living team

  2. Thank you so much for this! My soil factory had too many flies – the instructions said that it should be kept open with a sheet of paper to cover it. I’m guessing that your method with a container will not have a fly problem? If so I will try it. Please let me know about flies and insects as I live in an apartment and don’t get any direct sunlight. Thanks.

    1. You really shouldn’t have a fly or insect problem with a soil factory. I’ve never heard of anyone recommending to just cover it with a sheet of paper before! Definitely try the large container described in this blog piece. The pre-compost tends to take a little bit longer to break down in soil factories than when it is buried in the ground or in a compost pile. If possible, make sure you start with some good healthy soil (with lots of worms). We would love to hear how you get on 🙂

  3. Should the container for soil factory be air tight. I have balcony space , no ground space. Need to ensure no flies , pests etc .

    1. The container doesn’t need to be completely airtight; although a good fitting lid will help keep rain out and any bokashi odors in. As you are keeping your soil factory on your balcony, you won’t want to drill holes in the bottom to let liquids drain. We would therefore recommend adding extra garden soil to ensure that the soil factory doesn’t get too wet.
      Hope that helps. Please let us know if you have any other bokashi questions.

    1. Hi Daphne,

      It will work, but it will take longer for the pre-compost to break down. It is the life (bugs, worms, microbes, fungi etc) in the soil of the soil factory that breaks down the pre-compost. So the less life your soil in your soil factory has, the longer it will take to break down the bokashi pre-compost. Recycled potting soil is probably the best of your two options as there will be some biota in it.

      To help the pre-compost break down as quickly as possible we would recommend chopping your food waste into 1″ or smaller pieces, adding plenty of bokashi bran and leaving your kitchen composter for a little longer to finish the fermentation stage.

      Happy composting 🙂

  4. Hi, I use the container method on my balcony. The second batch was infested with black soldier fly larvae when I checked it after 2 weeks. I freaked out put the lid back on and ignored it for 2 weeks. After that most of the larvae was dead but still a few wiggling around.

    From comments above I shouldn’t be getting any bugs? I also had ants which isn’t such a issue.

    The container I use has 4 clips to hold the lid on. No holes. It’s not air tight but it’s a pretty secure cover. What am I doing wrong?

    1. Hi Auri,

      Thanks for your questions. Black soldier fly larvae are actually beneficial to the breakdown of the organic material. The adult flies do not eat and therefore do not cause a nuisance at all. If you can learn to live with them, then they will help your bokashi soil factory; though I understand if you don’t want them setting up home on your balcony.

      As you say, you shouldn’t get large numbers of flies and bugs attracted to your soil factory. Make sure you are letting your food waste ferment completely before adding it to your soil factory. A few things to do to encourage full fermentation; 1. Leave the bin for longer than the 2 weeks minimum, 2. Add extra bran, and 3. chop up your food waste before adding to the bin (ideally 1-2″, or smaller).

      Finally make sure to add a good couple of inches of garden soil on top. This makes sure that the bokashi pre-compost is thoroughly buried and should not attract insects.

      The lid you are using sounds perfect. It does not need to be airtight, just something to keep the rainwater out.

      Hope that helps,
      Nicki

  5. Hello,

    I’d like to use up some of the soil left in my plant pots last year in my soil factory, as well as a pile of soil we’ve had in the corner of the yard for many years. I haven’t poked through them yet to see what life is going on there already. Would it be okay to use this dirt in my soil factory if I add some mycorrhizal fungi to the mix as well as the Bokashi?

    I just don’t want to waste any of the dirt I have but I’m not confident that it’s the most ideal garden soil. Thank you for this great post and for the others who have posted questions, it’s so informative!

    Cheers,
    Jen

    1. Hi Jen,

      Thanks for the kind words. I agree, I never want to waste any dirt in my garden and with some good bokashi compost you can turn this dirt in productive, fertile soil. The left over dirt can be used for the soil factory, just be patient as it may take longer to break down if there isn’t much life in the dirt. No need to add any extra mycorrhizal fungi as there is already plenty of beneficial microbes and fungi in the bokashi pre-compost. If your soil in your soil factory is lacking in life, then I would recommend adding extra (ie more than 2/3 soil) and make sure that you mix the first two layers really well to break up any larger pieces of bokashi pre-compost.

      Alternatively, you could use the bokashi pre-compost in your planters. Make as you would a soil factory. Wait a few weeks and then plant directly in them. I like to do this at the beginning of the year as it is a great (and easy) way to get lots of compost into planters and containers.

      Hope that helps, feel free to keep asking any other questions.
      Happy composting
      the Bokashi Living team

  6. Hi! Do I just harvest the compost I need or should I remove the compost and start a new batch each time? If I harvest more than I need, how should this be stored…covered or exposed? Should it remain moist or should it be kept dry? Thanks!

    1. Either; whichever works for you. Sometimes I will just harvest what I need and keep adding bokashi pre-compost to the soil factory. Other times I will empty out the entire soil factory into my garden or containers and start the soil factory again. No need to store the finished compost in any special way. In a large container or large bag will be fine. Don’t let it get overly wet or dry and just use it whenever you want. Alternatively, just leave it in the soil factory until you need it and start a new soil factory if you run out of space.

      Happy composting
      the Bokashi Living team

  7. Our dog keeps digging up our bokashi burials and I keep putting my shovel through our watering system pipes. If I put garden soil and bokashi bucket mix (keeping it in the bokashi bucket for a month) into an old plastic rubbish bin will this eventually turn into soil ready to spread in the garden? How long should it take?
    Many thanks

    1. Hi Mark,
      Thanks for your question. Absolutely, you can add garden soil and bokashi pre-compost to a plastic bin; this is known as a ‘soil factory’. The bokashi pre-compost will take slightly longer to break down than if you bury it directly in your garden soil; typically 4 to 6 weeks. The length of time will depend on the quality of the garden soil; the more life in the soil, the quicker it will break down.

      To make a soil factory in your plastic rubbish bin:
      – Start with a thick layer (at least 3-4″) of good garden soil.
      – Add your bokashi pre-compost and mix well.
      – Add another 3-4″ of garden soil.
      – Check back after a couple of weeks and chop up any visible pieces of bokashi pre-compost.

      Hope that helps. Feel free to ask any other questions.
      Happy composting,
      The Bokashi Living team

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