Bokashi fermentation time: how long to wait and how to tell when it's ready

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"How long do I need to wait?" It's the question everyone asks when they're looking at their first full bucket. And when you go looking for the answer, you find figures ranging from ten days to six weeks. It's enough to make you wonder who's right.

This guide sets the record straight: it explains the different timeframes, why sources disagree, and our rule of thumb. Above all, it shows you how to recognize bokashi that's ready, by smell and by sight.

Two timeframes not to confuse

In the life of a bucket, there are two distinct phases:

• Filling: anywhere from a few days to a few weeks, depending on the size of the bucket and how many food scraps your household produces. Fermentation begins with the very first layers, but the scraps on top have only just been added.
• Resting, with the bucket full and sealed: this is the phase known as the "fermentation time." It starts on the day you add the last layer, not the day you started filling the bucket.

That's why we use two buckets: one fills up while the other rests. The method is explained in detail in our guide to the two-bucket rotation.

10 days, 2 weeks, 6 weeks: why sources disagree

Published figures vary by a factor of four:

• 10 to 14 days in many how-to guides and municipal recommendations, especially in countries with mild climates;
• 2 weeks for most bucket manufacturers, our own instructions included;
• 2 to 5 weeks among home users whose buckets were analyzed in a recent study;
• 6 weeks or more in the most cautious recommendations, followed by several months of maturing in the soil.

These differences are easy to explain. Temperature plays a big role: a bucket at 77 °F (25 °C) ferments faster than one in a cool pantry at 54 °F (12 °C). So does the type of food scraps, and the way the bucket is filled: a bucket filled slowly over a month is already well fermented at the bottom, while one filled in three days is starting almost from scratch. Finally, some sources are talking about fermentation alone, others about the time before you can plant.

Key takeaways

Our rule of thumb: at least 2 weeks with the bucket full and sealed, in a room between 64 and 77 °F (18–25 °C). Add 1 to 2 weeks in cold weather. The time it takes to break down in the soil comes on top of that.

Waiting longer is no problem at all. A well-sealed bucket that's been drained stays stable for weeks, even months. On the other hand, cutting the rest short can leave you with bokashi that isn't fully acidified yet.

Emy's tip

Write the date of the last layer on the lid with a marker: that's the date that starts the two-week rest.

The signs of good fermentation

After two weeks, open the bucket and use your senses. Successful bokashi shows these three signs:

Smell: sour, never rotten

This is the most reliable indicator. Bokashi that's ready smells sour and fermented: pickles, apple cider vinegar, sauerkraut, sometimes with a sweet or slightly boozy note. The smell is strong when you open the bucket, but not nauseating.

Appearance: sometimes a white bloom

It's common to see a white fuzz, like cotton balls, appear on the surface or between the layers. That's a good sign: it goes hand in hand with successful fermentation. If there isn't any, though, there's no need to worry, as long as the smell is right.

Texture: softened

The scraps have sunk down a little, their colors are slightly faded and their texture is softer, as if marinated. Everything has settled.

On the other hand, a rotten smell, a rotten-egg or ammonia smell, a black, slimy sludge, or widespread green, blue, or black mold all signal a problem. To find out what to do, see our guide on mold in bokashi.

"My food scraps look untouched": that's normal

This is the big surprise for beginners: when you open the bucket, you can still make out the banana peel, the apple core, the eggshells. It looks as if nothing has happened. Yet that's exactly what's supposed to happen.

Bokashi doesn't decompose food scraps: it ferments them, a bit like turning cabbage into sauerkraut. The cabbage keeps its shape in the jar; your scraps keep theirs in the bucket, too. They are acidified, stabilized, and already predigested by the microorganisms. It's a pre-compost, not finished compost. The actual decomposition happens afterward, in contact with the soil.

Did you know?

In home bokashi buckets analyzed recently, the liquid had a pH of 3.7 to 4.9, about as acidic as orange juice or a tomato. Lactic acid bacteria, the same families found in fermented foods, dominated the microbial population.

How temperature affects the timeframe

The microorganisms in the bucket work faster the warmer it is. To keep it simple:

• Between roughly 64 and 77 °F (18–25 °C): two weeks is enough in most cases.
• Between 50 and 64 °F (10–18 °C): allow an extra one to two weeks.
• Below about 50 °F (10 °C): fermentation slows down considerably; at around 41 °F (5 °C), it almost stops. It will pick up again once the bucket warms up.

In summer, fermentation is often faster, but stick with the two weeks anyway: they cost nothing and make the result more reliable. All our seasonal tips are in our guide bokashi in winter, in summer, and while you're on vacation. A good dose of activator, such as our Bokashi EM Compost Activator, also helps fermentation get off to a good start: see our guide on bokashi bran, what it does, and how much to use.

What's next? Breaking down in the soil

Once fermented, bokashi still has to turn into soil. Buried in the garden and mixed well into the dirt, it generally disappears within two to four weeks, sometimes longer in cold or compacted soil; it's estimated to take up to about two months to be fully absorbed. At first it's very acidic, so you need to wait at least two weeks before sowing or planting in the same spot; three to four weeks is even better.

From the first peel to soil that's ready for planting, you should generally allow six weeks to two months, a little longer in winter. The whole method is explained in our guide to burying your bokashi in the garden, and our guide no yard? covers options using pots and containers.

The bottom line

Fermentation time is counted from the last layer: at least two weeks with the bucket full and sealed, at 64–77 °F (18–25 °C), plus one to two weeks in cold weather. Waiting longer is no problem at all. Bokashi that's ready smells sour, may have a white bloom, and has a softened texture, even if the scraps keep their shape: that's normal, it's a pre-compost. It then turns into soil in the ground, in roughly two to four weeks.

Related products

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Other topics in the guide

Vermicomposting30 fact sheets →Composting25 fact sheets →EM microorganisms26 fact sheets →