In this video Nick from Roots Kombucha shows how to start a kombucha culture from a bottle of kombucha. All instructions can also be found beneath the video. Good luck!

What you need

  • a bottle of unpasteurized, unfiltered kombucha
  • a glass or food-grade plastic container with large opening
  • kitchen towel, rubber band

Ingredients (for 1 liter tea; we recommend to brew batches of 3 to 5 litres)

  • ~3 g (1 table spoon) organic black tea (e.g. English Breakfast Tea)
  • 1 liter water
  • 0,5 dl organic white sugar


Start by thoroughly cleaning all equipment. Like with all fermentation it is important to think about hygiene to prevent the wrong kind of bacteria from growing.

Step 1: Brew sweet strong tea

Boil water. Add the tea and let cook for 5 to 7 minutes. Strain the tea-leaves and add the sugar. Let cook for another 3 to 5 minutes. Take the pot off the stove.

Step 2: Cool the tea to room temperature

Let the tea cool to room temperature. To speed up the cooling you can immerse the pot (with the lid on) in cold water.

Step 3: Add bottle of kombucha

Poor the tea into the container and then add a whole bottle of unpasteurized kombucha to the tea. The ratio between tea and kombucha should be between 3:1 and 5:1, so three to five times as much tea as kombucha. Cover the container with the kitchen towel and fix it with the rubber band.

Step 4: Let it sit for 3 to 4 weeks

Place the container in a warm spot that is somewhat protected from sunlight. The ideal temperature is slightly over room temperature. Let the container sit for 3 to 4 weeks until a thin layer of kombucha culture has formed at the surface and the tea smells slightly of vinegar. The kombucha is ready now.

You now have a kombucha culture and can brew your own kombucha.

Learn how to brew kombucha in our video How to brew kombucha.

Good to keep in mind

  • You can use different varieties of tea to make kombucha, but keep clear from such varieties that contain essential oils such as Earl Grey. Roots Kombucha uses black tea because in our experience black tea gives the best result. Moreover black tea is used traditionally for kombucha brewing.
  • You can use other energy sources than sugar for your culture, e.g. agave syrup, but that might cause variation in your final product. Avoid honey, as honey naturally contains antibiotic compounds, which can inhibit the kombucha culture.
  • You can experiment with the amounts of tea and sugar you use to reach the strength and sweetness that pleases you most.
  • Try different flavoring agents – e.g. leaves, berries or roots – but always make sure to thoroughly clean everything you put into the kombucha.
  • After your kombucha culture has grown strong it will become necessary to split it. Simply tear the culture apart with the help of some kitchen utensil, which is usually quite easy to do. One half you can then store in a glass jar covered with kombucha in your fridge. That way you have a back-up culture or one to give away to a friend.
  • Keep an eye on your kombucha culture. If it starts to look and/or taste strange we recommend you stop using this culture and instead start a new one.
  • Don’t use ceramics to brew or store your kombucha. Kombucha’s acidity increases the risk that heavy metals leach out of the glazing into the liquid. Metal is not good for the kombucha culture either, with the exception of stainless steel. Glass, wood or food-grade plastic are the most suitable materials.
  • The ideal temperature for kombucha fermentation is 2 to 5 degrees over room temperature, but it works even at lower or higher temperatures. Lower temperatures lead to slower fermentation, higher temperatures lead to a faster process. Temperatures beyond 30°C (86°F) kill the culture.