We often get questions about mold in bokashi buckets. Mold can be a good sign. But it can also be a sign that things are going bad. It really depends on the color of the mold.
No mold in bokashi bucket
Often times, especially with a well sealed airtight bokashi bin, you may see no mold at all on your bokashi food waste. That is perfectly normal, and another sign of a healthy bin. The contents should still have the distinctive sweet, pickly smell of bokashi composting.
A successful bokashi bucket does not have to have white mold on it.
White mold in your bokashi bucket
If the mold is white then don’t panic! White mold on your bokashi bucket is ok but it is a sign that your bin is not completely airtight and that some air is getting in to your bokashi bucket. Make sure that your spigot and lid are fully closed.
The white mold may be white fluffy mycelium clouds, or smaller specks or strands of white on the surface of the food waste.
The white mold is actually a fungi and shows that the food waste is fermenting rather than putrefying. Fermentation is exactly what you want in your bokashi bucket.
Note: White mold is often considered a sign that some air is getting in to your bokashi bucket. A completely airtight bokashi bucket typically shows no white mold.
Blue or green mold
Black, blue or green mold is a sure sign of a problem with your bokashi pre-compost. These darker colored molds are signs of rotting and putrefaction. These should not be present in bokashi composting.
Often times, dark mold is a sign that your bin has failed. When this happens, dispose of the contents of the bokashi bucket or bury them deeply in the garden. If burying, add a couple of handfuls of bran with the failed pre-compost and leave undisturbed for a few months. The failed pre-compost will eventually assimilate with the soil.
In some cases, if there is only a little blue, green or black mold, you may be able to recover the bucket. Add a couple of handfuls of bokashi bran to the small patch of dark mold, cover and close the lid. Check back in a day or two. The beneficial bokashi microbes may out compete the blue and green molds and get your bokashi bucket back on track.
If you see dark mold on your food waste, make sure to check our troubleshooting guide to help prevent it happening again.
Most commonly problems occur because the bokashi bucket is not completely airtight. Make sure your lid is tightly sealed, the composter is not cracked, and that the spigot is completely closed. Also, make sure that enough bran is being added to the food scraps. We recommend adding about 1 tablespoon of our premium bokashi bran for every 1″ layer of food scraps. More if you are adding hard to compost items such as meat, bones and dairy. Another common problem is using bran that is no longer viable. Bokashi bran needs to be fresh (less than 18 months old) and needs to be stored correctly (How to store bokashi bran). Bran that is old or stored improperly will have far fewer active bokashi microbes and be inefficient for bokashi composting.
Other posts you might like to read:
Bokashi composting: how to get started
Troubleshooting: What to do if your bokashi bin goes bad
How much bokashi bran?
I agree that the white mold is related to air getting into the Bokashi process. The overall teaching is that the process is about being anaerobic, no air if possible, so the LAB, Lactic Acid Bacteria can do the fermenting. A perfect system is difficult to create with backyard Bokashi, I realize this. I take steps to keep air out by implementing one rule. I fill each of my Bokashi buckets with correct scraps and bran ratio at the start of each bucket. I do not “fill as I go” the Bokashi buckets. I don’t use a spigot either it’s a close two bucket system. This in itself allows me to fill the buckets and close the buckets for a total of two lid opening per batch. My question is why is it explained that the white mold is OK… or that “The white mold is actually a fungi and shows that the food waste is fermenting rather than putrefying. Fermentation is exactly what you want in your bokashi bucket.”. I thought the LA Bacteria do the fermenting. Why is it that fungi that need oxygen are being praised for being in a system that is supposed to be oxygen free?
Great question! As you say, the white mold occurs when air gets in to the bokashi bucket. And, as you also say, in an ideal bokashi system it would be completely airtight and the system would be entirely anaerobic. However, from time to time, maybe when the lid isn’t fully closed, some air can get into the system and cause white mold.
If people are seeing this white ‘mold’ for the first time, it can be concerning. The blog post is trying to help people differentiate between different types of visible mold, ie. white mold is ok, but blue/green/black mold shows there is a problem. The sentence you refer to should probably be reworded to clarify that blue/green/black mold shows that the food waste is putrefying, whilst white mold shows that some air is getting in but not enough to cause the fermentation to fail.
Hope that helps 🙂
I just buried my bokashi (after a month or so in the bucket) and a light gray fungus or possibly mold started growing on the surface. It’s kind of knobby with almost a root. Any idea why this it and or if this is bad?
Seeing white or grey mold on the surface of your soil after burying your bokashi is a great sign! It is perfectly normal and shows that the beneficial bokashi microbes are thriving. The bokashi compost is helping build a healthy soil food web… your plants will love it! Keep doing what you’ve been doing. Happy composting.
I made a bokashi bucket about 2 weeks ago. Went to check it and there’s no white mold (except a lil on some oranges but I’m not sure if that’s just citrus mold or mold mold). It doesn’t stink, however, it smells like oranges (there’s a lot of oranges in there) and not much like vinegar or pickles. Is that bad? Everything looks ok and there’s no bad smells or bad mold. I just wanna know if I’m good to add it to my compost..thank you so much!
Hi, Thanks for the questions. Yes, this sounds absolutely fine. As long as there is no putrid smell or blue/green mold then you are good to bury. It’s likely that the smell of the oranges is overpowering the typical pickle smell that you associate with bokashi composting.
Happy composting 🙂
Dear Bokashi Living:
It’s been almost two weeks since my Bokashi bin is full. I am thinking of making a soil factory by mixing the pre-compost with some left-over potting mix and leave it indoor since it is still frozen outside. The pre-compost looks to have yellowish mold (maybe from the coffee grounds). My soil factory container is a large plastic box with some small holes on the top and bottom. Is it safe for me to leave the box indoor (in my kitchen)? Would it be safe for me to mix the pre-compost and potting mix indoor because I might inhale mold spore? Thank you very much.
February 26, 2022
Thanks for the questions. Could you share a photo of the mold (I’m not sure if you can share a photo in the comments, here. If not, please email it to firstname.lastname@example.org)?
Your plans for the soil factory sounds fine. However, you are probably best to keep it outside, if you have the space. The soil factory often produces liquids, which will likely escape through the holes in the bottom of your soil factory. This could cause odors in your home. Also, by keeping the soil factory outside, then it will be more exposed to the bugs and life that you need in your soil. The cold temperatures will slow down the break down but will not harm the soil factory process.
I have a white mould which appears normal but also for the first time a bright orange mould! Is this ok for burying in the garden as I usually would the compost? I want to plant on it fairly quickly
Thanks for the question. We don’t have any first hand experience of orange mold in a bokashi bucket! If there is only a small area and the rest of the bucket looks and smells as usual, then this bokashi pre-compost will be fine to bury. If you want to be able to plant on it fairly quickly, then make sure that you mix and chop it well when you bury it. The time spent mixing and chopping allows the soil web to get to the fermented food waste and break it down quickly.
Happy composting 🙂
My bokashi compost did very well, but after depositing into a bigger bin with some soil to over winter, I discovered green and blue mold after two weeks. I read that it might be possible to save, but wondering if this has to do with the amount of moisture I found in the bin?
Would it be better to store outside for the winter and restart in the spring? We were -28 yesterday and today so things will definitely freeze.
Once your bokashi food waste is fully fermented and added to your soil it is less sensitive to low temperatures. The microbes will slow down and may go dormant in cold weather, but will recover as the temperatures rise. So your (very) cold temperatures will not have harmed your bokashi compost. The blue/green mold may have developed on pieces of bokashi’d food waste that were not fully mixed in with the soil.
We recommend giving your bigger bin of soil and bokashi pre-compost a thorough mixing and chopping (either now, or when the soil is unfrozen and workable). Then add a few inches of fresh garden soil to the top and leave it to finish breaking down. Next time you add bokashi pre-compost make sure to mix and chop it thoroughly with the soil as you bury it. Large unmixed pieces take longer to be assimilated in to the soil.
If you continue to notice some patches of blue/green mold after burying the bokashi pre-compost, then go back to the basics with your bokashi composting. Make sure that you are chopping your food waste small enough (ideally less than 1-2″), make sure that you are adding enough bokashi bran (around 1 tbsp per 1″ layer of food) and that you are leaving your waste to ferment for at least 2 weeks after adding the final layer of food waste and bran to your bokashi bin.
Happy composting 🙂
HEllo, I have the same situation, but the blue mold is almost everywere on the top layer…
I think I added too little soil, due to lack of space in the box I use, and did not cover the leftover food scraps enough.
If I divide the stuff I have in the box, and add more soil and bokashi bran, do you think I can save it still?
Or should I dump everything into our municipal foodwaste bin?
MAybe an intermediate solution could be to remove the top layer and try to save what’s below? I thin I screwed it this time… 🙁
Thanks for the question. Yes, removing the top layer with the blue mold would be a good start. Then, as you suggest, mix in some extra bokashi bran. Make sure to mix the contents thoroughly. This is an important step as it breaks up any larger pieces of bokashi pre-compost and lets the life in the soil get to the bokashi pre-compost. Then sprinkle on a bit more bokashi bran and add a good thick layer of good quality soil (something with lots of life in it, not ‘dead’ store bought bagged compost).
You should still be able to save it.
If you don’t have space in your soil factory, then you could always dump half in your municipal food waste bin and work with what you have left. At least that way you will get some compost for your efforts 🙂
Let me know how you get on.
You mentioned that it is normal to have mould in the soil factory. Once my soil factory is ready for some potting do i just remove the top mouldy area?
The white mold can just be mixed in with the rest of the compost. The white mold is a sign of healthy bokashi microbe activity; you want to add as much of this to your garden as possible 🙂
Hello, I am just trying bokashi the first time and I fermented the first basket successfully, including good smell. I prepared a soil factory on my balcony (as per your article) to finish the process using old soil from plants and some new soil from a garden center (do not have where to get a garden soil). One week later when I opened the soil factory to check, instead on the black soil I see white mold, covering about 90% of the surface. Is it Ok or have I done something wrong?
White mold is a sign of healthy bokashi microbes. The white mold forms when the microbes are exposed to air, so it commonly occurs on top of soil factories. It is a sign that you have done everything right 🙂
I just started doing bokashi composting. I live alone so don’t collect much food waste each week to put in my bokashi bin, so I am concerned the scraps will start to mold BEFORE I even put in the bin. What do I do in the interim. Put in the freezer so it doesn’t decompose? I don’t want to ruin my compost before I even start.
You are correct to be concerned about the food waste going moldy before you add it to your bokashi bucket. Moldy food can cause the bokashi bucket to fail. But don’t worry, you have a couple of options. You can simply add the food waste that you have every day or two. There is no need to wait for a full inch layer before you add the food waste. If you are adding a thinner layer of food waste, you can also add a bit less of the bokashi bran. Alternatively, as you suggest, you can keep the food waste in the fridge until you have enough to add to the bokashi bucket.