How to Make Bokashi Bran from Coffee Grounds

This week in the Flog:

  • How you can make your own bokashi bran for almost nothing
  • Putting to good use Starbucks coffee grounds

Some time ago I wrote an article about Bokashi – everything you need to know from start to finish about how to bokashi. Later, I followed it up with an article all about bokashi bran – this was a great article that might surprise even experienced bokashi practitioners – you can make your own bokashi bran at home with nearly anything – plus sugar, water, and a bit of lacto inoculant.

This week’s article follows up the bokashi bran article I wrote a few weeks ago, with a typical example of making bokashi bran at home. The thing is, Starbucks is everywhere. Starbucks branches all over the place – in parts of Manila you can’t walk 3 blocks without running into a Starbucks shop. And Starbucks gives away their used coffee grounds. And no one takes them! It’s amazing, such an awesome resource, and Starbucks has actually taken the initiative to give it away, and no one takes it! Amazing. Well I take it.

So I have all this ground coffee out on the balcony next to the planters…it is excellent fertilizer as it is, and I’ve mixed some in with fresh soil as a soil amendment already. It contains high levels of Nitrogen and Potassium, as well as minor nutrients which plants love. But now I’m going to make it even better, and make a vital ingredient for my bokashi bin as well. I’m going to make coffee ground bokashi bran!

This is simple. Here are the rough steps:

  1. Weigh dry coffee grounds (if they are wet then estimate)
  2. Weigh out 1/3 that amount of sugar (flexible, can be up to 1/2)
  3. Mix coffee grounds, sugar, and add some lacto, like 1tbsp/L.
  4. Add enough water to make the mixture wet. It can be much wetter than normal compost, but no need to make a slurry, just make it nicely moist.

In this case, I have substituted the lacto for some Anaerobic Compost Tea (AnCT). Anaerobic tea brewing is something we’re still working on, but it’s awesome. It gives you a really good way to make your own fertilizer that is both nutrient strong and microbe rich, something traditional aerated compost tea can’t do.

Here, you can see the ingredients – the coffee grounds, AnCT (in place of lacto, which works great also), and sugar. My coffee grounds are a bit wet, so I’m estimating the amount of sugar needed. Also, I don’t need to add any water.

Bokashi Bran Ingredients

Here are the simple ingredients needed to turn your coffee grounds into bokashi bran

Everything gets mixed together in a big loose pile on the tarp. It gets mixed thoroughly but quickly – the less time we expose it to air the better – bokashi is an anaerobic process and we want to get it that way as fast as possible. Here is the pile all mixed up:

Bokashi Bran - mixing

The ingredients quickly get mixed up. Don’t mix for too long, you are introducing air into the bran.

Now the bran goes into the container. Here’s an important tip: only add a little bran at a time, then pack it down. Then add a bit more and pack it down. The goal here is to pack down the ingredients so there is no air space left. Squeeze all the oxygen out of the substrate (bran, or in this case coffee grinds), so that fermentation can start immediately. Here you can see what I mean by packing your bokashi bran:

Bokashi Bran Packing

Add grounds a bit at a time, and pack down hard. You want to squeeze all the air out of the bokashi bran. It needs to be anaerobic.

Another important tip – leave as little airspace as possible above the substrate. In this case, since there is significant space in the container, I’m going to cover the top of the bokashi bran with plastic. That will keep the top fairly anaerobic.

Bokashi Bran - covered

I used a plastic bag to cover the surface of the bran to help keep it that much more anaerobic (there is some space in the container I’m using to hold it)

Also, you’ll notice the container I’m using is plastic. You want to use a nice rigid container, ideally not just a plastic bag. That way if/when you move it, it won’t get deformed and have air introduced into the substrate. All these little things will help you to successfully make your own bokashi bran at home, for pennies.

Let’s look at the completed bokashi bran setup. You can see how little it looks after being packed into the container! Notice the light patches within the container (air pockets) go all the way to the bottom – it’s not soaking wet, just fairly moist. While it wouldn’t be terrible if it were soaking on the bottom, it’s a little nicer to just have it moist and not dripping wet. Anyway now we’re ready to ferment!

Bokashi Bran - sealed up

Here is the final setup, ready to ferment. It will sit outside in the shade for at least a month or so. During that time it will ferment and become biologically active, and become a great inoculant for the bokashi bin!

After fermentation, it looks much the same as it did before. It even still smells a bit like coffee, but now there is a very sweet/sour smell as well, indicating a successful ferment. I also tested the completed bran to make sure it was good. A bit of bran added to water and then put under the microscope is enough to see the LAB. If you don’t have a microscope, add a bit of your bran to a sealed container with some water and sugar, then wait a few days. After a few days, air pressure will start to build up in the container – this is a byproduct of fermentation, and is an indicator that you have a healthy population of lacto in your bran.

Where will I use this nice coffee grounds bokashi bran?

Good question. I’m going to feed some to the cockroaches, who in my experience prefer it fermented rather than fresh. I’m also going to add a bit to some potted plants that could use a little boost. And for the bulk of it, I’ll use it like you use bokashi bran – in my bokashi bin! It gets mixed in with each addition of kitchen scraps that go in the bin. If you’ve read our article on bokashi, you know that bokashi bran is used to keep the bokashi bin stable and on track fermenting the kitchen scraps.

  • Yvette

    I’m loving all the information on this site. Thank you. I am keen to check lacto populations under a microscope but have no background in identifying them or even using a microscope. Is it a relatively easy thing to recognise different bacteria or would I need some kind of training? I make cultured foods in the kitchen for our consumption too hat I would like to put under a microscope.

    • Patrick

      Hey Yvette, that’s no problem, you can pick that up pretty easily. You will need a microscope, then I would do some Google work to learn about lacto and what they look like. They are rod-shaped bacteria and pretty easy to see once you know what to look for. Start with something easy, like a pure LAB serum before it’s mixed with molasses. you’ll see about a billion of them in that. i’ll try to post a pic of what that looks like. It is still somewhat guesswork – you are only seeing “rod-shaped bacteria” which could be any genus or species of rod-shaped bacteria, but you know from your preparations, these are LAB you’re seeing. Later you’ll learn about the others like the round and spiral shapes, other things like ciliates, flagellates, fungi, rotifers, etc…

  • emma

    why is it used to feed cockroaches?ty

    • Patrick

      Hi Emma – I use it to feed the roaches cause it’s free. When I run out of kitchen scraps to feed them (which are also free, sort of), I feed them this, as well as some animal feed bokashi which contains some grounds anyway.

  • Jean-Jean

    Nice Article.
    How do you evaluate the dry weight when the coffee grounds are wet ?
    Do you divide by 2, 3 or 4 ?
    For instance in that particular example, how was the weight and how was your evaluation ?
    Thx again.

    • Patrick

      Honestly I just guessed after weighing it wet. I weighed it on the scale, then grabbed a handful of it and squeezed it, guessed the percentage of water, and deducted that percentage from the weight. But you don’t have to be that exact (as if that were even exact). You can add anywhere from a little to a lot of sugar and you’ll be ok. I tend to err on the side of “more”, so I aim between 1/3 and 1/2 part sugar, sometimes up to 1:1 sugar by weight for light things (since in those cases it doesn’t require much sugar anyway).

      Cheers – Patrick

  • Kris

    Hi There!
    I made my bran with coffee grounds, following the directions here. Thank you so much for the detailed descriptions for everything. 🙂
    I am currently using the sugar water method to determine whether I have fermentation or not. If there is no fermentation, what’s the next step and what do I do with the bran that I made but is actually just coffee grounds with some other stuff mixed into it?
    Thanks in advance!

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