top of page

Why Your Kombucha is Taking a Long Time to Ferment (And How to Fix It!)

kombucha fermentation

Kombucha is usually super fun and easy to make. However sometimes my home brewed booch takes a lot longer than normal to ferment. Leaving my fridges and stomach empty of tasty kombucha for weeks at a time.

What has led me to wonder, what's causing my kombucha to take longer than normal to ferment and how can I fix it?

Most 1st fermentations of kombucha will take 1-2 weeks to finish. If kombucha is taking longer than this to ferment it could be because of too cold of a brewing environment, a small, old and/or inactive SCOBY, the brewer not using enough starter tea or sugar, a lack of oxygen flow to the bacteria culture, or a contamination in the brew.

In this article I’ll cover all of these variables in detail so that you can figure out what’s causing your kombucha to take so long to ferment and fix it for future brews. If you’re short on time and are looking for a quick fix, here's a short table summarizing the article.

Why Your Kombucha is Taking so Long to Ferment

kombucha fermentation tips

Ok lets get started!

The Process of Kombucha Fermentation

Before I get into the factors that may be causing your kombucha to ferment slowly, It’s important that I quickly go over the process of kombucha fermentation to make sure we’re on the same page.

If you’re already familiar with how kombucha is made then you can just skip this section.

All booch begins as sweet tea. What turns this sweet tea into sweet and sour probiotic kombucha is a living culture of bacteria. This culture of bacteria, known as a SCOBY (Symbiotic Culture of Bacteria and Yeast), eats the sugar and caffeine from the sweet tea and produces acids, carbon dioxide, and alcohol.

Once it has eaten enough sugar to make the kombucha bitter tasting, the SCOBY is removed and the 1st fermentation is complete. Normally this process only takes 1-2 weeks, but sometimes certain situations and mistakes can cause it to take 3,4 or even more.

In this article I’ll be talking about how to keep the 1st fermentation of your kombucha from taking longer than 1-2 weeks so that you’re not waiting around for months for a single batch of kombucha.

After the 1st fermentation is done we technically have kombucha, but it's not carbonated or flavored yet.

The carbonation and flavor is added in a 2nd fermentation. During this stage, the kombucha is sealed in glass fermenting bottles that are filled with fruit, juice, or herbs for flavoring.

Over the course of a few days, the kombucha in the bottles develops carbonation and flavor. It’s then refrigerated and ready to be drunk!

Ok, now that you have an overview of the kombucha brewing process, let's talk about what may be causing your 1st fermentation to take longer than 1-2 weeks and some of the things you can do to fix that.

Why Your Kombucha Is Taking a Long Time to Ferment

Too Cold Of a Temperature

The most likely reason why your 1st fermentation of kombucha is taking longer than it should is because the environment it’s being brewed in is too cold.

This is because when kombucha is brewed at colder temperatures, it’s living bacteria culture becomes less active. And a slower bacteria culture means that fermentation will take longer.

For example when I brew kombucha during the summer my 1st fermentation, brewed around 75 degrees F, usually takes from 7-10 days. But when I brew kombucha in the winter, at a temperature of around 65 degrees F, the 1st fermentation can take 3-4 weeks.

So at what temperature should kombucha be brewed at? Well kombucha can be brewed at a temperature of anywhere between 65-85 degrees F (18-29 C). However, the ideal kombucha brewing temperature is 75-78 degrees F (24-26 C).

If you are brewing kombucha during the wintertime or in a colder climate, check the thermostat of the room it’s in, or use a thermometer or temperature strip on the brewing vessel to see if the temperature is within this range.

How to Keep Your Kombucha Warm

If you check the temperature of your brew with one of the methods mentioned above, and find that it is too cold, there are ways to warm it up.

If your kombucha is only a few degrees too cold, you can either move it into a warmer area of your house, or turn up the thermostat a few degrees.

However if you need to warm up your kombucha significantly, the best and easiest way is to use a kombucha heating pad. A heating pad wraps around your brewing vessel and can warm your kombucha up 10-15 degrees F (5- 8 C).

Some even have thermostats so all you have to do is set it and forget it and it will adjust by itself to keep the kombucha at that temperature. Others have multiple heat settings so you’ll have to keep track of the temperature and adjust it yourself.

Kombucha heating pads are made to keep your kombucha warm 24/7, so they are super energy efficient and work on very little electricity, which means you won’t have to worry about them running up your electricity bill.

My favorite wrap-around heating pad is Perfect Kombucha’s Fermentation Heater. This kit allows you to control the temperature of your kombucha with 4 separate heat settings, and allows you to monitor the temperature accurately with the included temperature strip.

Perfect Kombucha has so much confidence in the quality of their heating pad that they guarantee you a 100% refund within one year of purchase if you’re not satisfied. If you’re interested, you can find their wrap-around heating pad on Amazon here.

If you’re on a budget but still need to heat your kombucha, you can get VIVOSUN’S Wrap Around Heating Pad for only $10 and with free shipping on Amazon here.

A few other things you can do to heat your kombucha are:

  • Store the kombucha above the refrigerator or on a high shelf where the air temperature is usually warmer.

  • Wrap the kombucha with a towel for insulation.

  • Place the kombucha, on top of a plate, on an appliance that's always running like a DVR.

A Small, Old, or Inactive SCOBY

If you’ve checked the temperature of your brewing booch and found that it’s above 70 degrees but youre kombucha is still taking 3-4 weeks to ferment, another possible explanation for the slow fermentation time is the size, age and/or activity level of the SCOBY.


The bigger the bacteria culture and more bacteria and yeast in the kombucha, the faster it’s going to ferment. This is because with more organisms in the booch, the sugar is being eaten quicker and more fermenting is being done.

So if you’re SCOBY is small, (less than ½ an inch thick, doesn’t cover the entire top of the kombucha) it’s going to ferment slower than a larger one, and may be the cause of your slow fermentation problem.


While in one sense a larger sized SCOBY is better for fermentation time, bigger isn’t always better. This is because an older, thicker SCOBY may have dead and inactive layers.

The common belief in the world of kombucha home brewing is that older layers of the growing SCOBY are less active and efficient at fermenting as new ones. And that if you don’t peel off these old layers, your kombucha will develop an “off flavor” and take much longer to ferment.

So if your kombucha is taking a long time to ferment and you’ve been making kombucha for a while, check out your SCOBY and see if any older layers look like they need to go.

Activity Level

The final aspect of your SCOBY that may be leading to a slow fermentation is the activity level.

If your SCOBY is newer, or has been refrigerated recently it may be a little slower in fermenting your kombucha.

This is most common when you buy a new SCOBY online. Since it has been refrigerated and isn’t yet in the routine of fermenting kombucha it won’t work as quick at first. But give it a few brewing cycles to get going and the process should quicken up.

Not Enough Sugar

Another factor that can play a role in the fermentation time of kombucha is the amount of sugar used.

Since sugar is the key food or fuel that the bacteria and yeast use to do the process of fermentation, if there isn’t enough of it fermentation will take longer, or won’t happen at all.

The common guideline is to use 1 cup of sugar per gallon of kombucha, so as long as you’re close to this amount sugar shouldn’t slow down your fermentation time.

Not Enough Starter Tea

Another ingredient that can affect your fermentation time is starter tea. Starter tea is just a few cups of kombucha from a previous brew that are added at the beginning of a new batch to get things going.

The starter tea and it’s extra bacteria and yeast give the SCOBY the right acidic environment to kick start fermentation, so without enough of it fermentation could take longer to get going.

The general rule is to use 2 cups of starter tea per gallon of kombucha, but if you’re having trouble with the speed of your fermentation and have tried some of the other things on this list already using a few extra cups could help to speed fermentation up.

A Lack of Oxygen Flow to the Bacteria Culture

Although they don’t look like us, even bacteria and yeast need to breathe. Which is why if you seal the jar of your brewing vessel airtight or use a container without a big enough opening the culture may not get enough oxygen to stay healthy and active. Leading to a slow fermentation time or no fermentation at all.

To avoid this problem, never use a lid or cap to seal your kombucha brewing vessel. You should, however, cover your brewing vessel with some type of cloth or rag to keep fruit flies and other contaminants out while still allowing airflow.

I personally just use a cut up old cotton t-shirt and secure it around the brim with a rubber band.

As far as the size of the opening of the jar, I don’t have a specific number or rule for you, but you can check out the jar I use to brew kombucha on Amazon here to use as a guideline/reference.

Final Thoughts

While the most likely reason your kombucha is fermenting slowly is that it is brewing in too cold of an environment, the size, age, and activity level of the SCOBY, amount of sugar and starter tea, and level of oxygen flow to the bacteria culture can also play a role in kombuchas speed of fermentation.

Hopefully after reading this article you can work through each of these variables to fix your slow brewing kombucha and start making great tasting booch every 2 weeks again!

If you’d like to learn more about kombucha, including special brewing tips to make your booch the best it’s ever been, be sure to check out the rest of my website! Have a great day!

Recent Posts

See All

How to Tell if Your Kombucha SCOBY is Dead

A healthy and active SCOBY is one of the most important parts of making a good home brew of kombucha. But what if you’re SCOBY hasn’t been doing what it’s supposed to and you think it might be inactiv


bottom of page