What is a SCOBY? How to Grow a SCOBY and Brew Kombucha

How to Make a Kombucha SCOBY

With just a little patience and the right starter, you can grow a kombucha SCOBY from store-bought kombucha. When choosing a kombucha for this process, look for a raw, neutral-flavored variety with plenty of stringy floaties or sediment at the bottom of the bottle—these are the living microbes that will help form your new SCOBY. I like GT’s Trilogy or Honey Crisp Apple for more neutral flavor options.

Before starting, drink most of the kombucha, but reserve at least ¼ cup and keep as much sediment as possible. This concentrated liquid contains the beneficial bacteria and yeast needed to seed a new SCOBY.

Next, brew a batch of sweet tea starter liquid (recipe below). Once it has cooled to room temperature, pour the reserved kombucha and its sediment into a clean jar, then fill the rest of the jar with the cooled sweet tea. Cover it with a breathable cloth lid, secure it with a rubber band, and let it ferment undisturbed for 7 to 14 days. Over time, you’ll see a new SCOBY forming on the surface—a sign that your homemade kombucha culture is coming to life!

You can also buy a kombucha starter culture to grow a SCOBY and begin brewing your kombucha.

What is a SCOBY and How Should It Look?

At first, you’ll notice a thin, transparent film forming on the surface of the sweet tea. This is the early stage of SCOBY formation, so try not to disturb it; it needs time to develop. As the days go by, the film will gradually thicken and become more opaque, shifting to an off-white or light brown color. The texture should be smooth and shiny, though its exact color may vary depending on the type of tea used.

Within 12-30 days, your SCOBY should be fully formed. It may start as a thin, patchy layer, but don’t worry, it will grow as you brew more kombucha. Most mature SCOBYs reach a thickness of about ½ to 1 inch, though size can vary depending on fermentation conditions. Each batch helps strengthen the culture, so even a delicate SCOBY can become more robust over time!

Pictured above is about three days after adding some store-bought kombucha to freshly brewed sweet tea. Below is about four days later. You can see that the carbonation from the store-bought kombucha caused some bubbles in the SCOBY.

How to Store a SCOBY

Each time you brew a fresh batch of kombucha, a new SCOBY will form on the surface of the liquid. The original SCOBY, now called the “mother,” will be at the bottom, while the newly formed “baby” will be at the top. Over time, you may end up with multiple layers in your fermentation jar. Right now, I have four stacked in mine, all working together to ferment sweet tea into kombucha.

If you find yourself with extra SCOBYs, they’re great to share with friends, start new batches, or even sell—some people list them on Etsy! If you’re not ready to use them right away, you can also store extras in the fridge in a SCOBY hotel to keep them preserved until you need them.

What is a SCOBY Hotel

If you brew kombucha often, you’ll quickly accumulate extra SCOBYs. So, what’s the best way to store them? The answer is a SCOBY hotel—a simple way to keep extras healthy and ready for future batches.

Setting up a SCOBY hotel is effortless. Start by placing all your extra SCOBYs in a large, clean jar. Then, brew a fresh sweet tea and let it cool to room temperature before pouring it over the SCOBYs.

Cover the jar with a breathable cloth lid secured with a rubber band, then store it in a cool spot. Unlike active brewing, a SCOBY hotel doesn’t need frequent attention—feed it fresh sweet tea every four weeks to keep the culture thriving while reducing maintenance.

Can Kombucha Grow Mold?

Many people worry about accidentally growing mold, and that’s a valid concern. While kombucha can grow mold, it’s rare and easily preventable with proper sanitation and fermentation conditions.

The most common cause of mold in kombucha is unsanitary equipment. To avoid contamination, thoroughly clean your fermentation jars, utensils, cloth covers and hands before handling your SCOBY.

A healthy SCOBY should be off-white to light caramel in color. If you ever see fuzzy blue, green, white, black, or gray spots forming on the surface of the SCOBY or the sides of the jar, that’s mold—and unfortunately, it means the batch is unsafe. Mold spores spread throughout the liquid, so scraping it off won’t fix the issue. If mold appears, discard everything and start fresh.

To ensure a safe fermentation, you can test the pH of your kombucha during primary fermentation using pH strips. A properly fermented batch should have a pH between 2.7 and 3.7 after about 12 days of fermentation. It should also smell lightly sweet and pleasantly sour, never musty or rotten.

How to Feed a SCOBY (Primary Fermentation)

Feeding a SCOBY is part of the primary fermentation process in kombucha brewing. It should be fed fresh sweet tea every 12 to 30 days to keep the culture healthy. The timing can vary greatly depending on the temperature. Warmer conditions speed up fermentation, while cooler environments slow it down. Most batches are ready to move to secondary fermentation within7-14 days (I personally think 7 days is too short, but it’s technically fine).

Once the tea has fermented, it is ready for secondary fermentation. At this stage, the SCOBY is removed, and the fermented tea is bottled in carbonation-safe bottles along with flavoring, such as fruit juice or herbs. This step allows the kombucha to develop its natural fizz and deeper flavor before it’s ready to drink.

Kombucha Second Fermentation, Flavoring, and Bottling Recipes

• Blood Orange Kombucha with Sage
• Summer Peach and Pomegranate Kombucha
• Rosemary and Grapefruit Kombucha Flavor Recipe

Beverage Fermentation

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Kombucha Primary Fermentation (how to feed a SCOBY)

Learn how to feed a kombucha SCOBY also known as kombucha primary fermentation.

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• Prep: 10 min 10 minutes
• Cook: 10 min 10 minutes
• Total: 20 min 20 minutes

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Ingredients

• 50 grams organic sugar
• 5 grams organic tea
• 1000 mL water
• 1-liter glass jar
• 1 kombucha SCOBY (or 1 cup store-bought raw kombucha)*

Instructions

1. Gather your ingredients
2. Boil your water and dissolve the sugar in the water.
3. Steep the tea in the hot water for 5 minutes. If using tea bags, simply remove them. If using loose leaf tea, strain all the tea leaves from the mixture.
4. allow the sweet tea mixture to cool completely. It should be room temperature before moving on to the next step.
5. Once it is cool, add the kombucha SCOBY. (SCOBY can come from kombucha liquid, or pellicle, or both). Some SCOBYs float, others may sink to the bottom, either way it’s fine. (You can add in store-bought raw kombucha here to grow a SCOBY for the first time).
6. Cover the jar with a cloth lid and rubber-band. You must use a cloth lid to allow oxygen flow. Make sure it’s clean and free from lint. 
7. Keep the jar of sweet tea with the SCOBY at moderate room temperature, out of direct sunlight for seven days. Temperature should be between 65-78 degrees F.
8. After 7 days you should notice that your SCOBY is thicker or see another SCOBY forming on the surface. You can let primary fermentation go anywhere from 7-30 days. I recommend ~15 days.
9. Make a fresh batch of sweet tea as in the previous directions.
10. Remove the SCOBY from the fermented tea and place it in the jar of fresh sweet tea. Set the fermented tea aside for bottling. Add a tablespoon of already fermented tea to the fresh batch.
11. The fermented tea is now ready for flavoring and bottling (secondary fermentation)
12. For secondary fermentation, you need pressure safe glass bottles and fruit juice for flavoring. I typically fill the bottles half way to 3/4th of the way with fermented sweet tea and the rest with juice.
13. Once the bottles are sealed, carbonation builds in the bottles. Secondary fermentation can take anywhere from 5 to 12 days depending on the temperature and amount of juice added.

Notes

• SCOBY can come from kombucha liquid from a previous batch, or a pellicle, or both liquid and a pellicle. You can add in store-bought raw kombucha as the SCOBY, to grow your own SCOBY pellicle for the first time.
• Click here to learn about the best tea for kombucha

Reference

Microbial Diversity of the Symbiotic Colony of Bacteria and Yeast (SCOBY) and its Impact on the Organoleptic Properties of Kombucha

Microbial Composition of SCOBY Starter Cultures Used by Commercial Kombucha Brewers in North America

Microbiology and antimicrobial effects of kombucha, a short overview

Kaitlynn Fenley Food Microbiologist and Fermentation Specialist

Kaitlynn is a Food Microbiologist and FSPCA-certified fermentation specialist. An alumna of the LSU College of Science, she combines her academic background in microbiology with her Cajun heritage to create safe and delicious recipes.

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