Where I live (California), adult recreational use of cannabis is legal. In a brief stint as brewer for a local cannabis beverage company, I learned how to infuse probiotic beverages with a cannabis simple syrup. The additional sugar in the syrup works well in a secondary fermentation of either kombucha or water kefir.
I found that the secondary fermentation with cannabis syrup happens more slowly than with other sweeteners which I commonly use (fresh squeezed fruit juice, dried or fresh herbs, ginger), so the length of time in secondary fermentation is longer.

The syrup I made used some old trim/shake for which I did not know the THC content, so I had to estimate it. Read more about that.
STEP 1: Make Cannabis Syrup
You will first need to create cannabis-infused simple syrup.
STEP 2: Make Kombucha or Water Kefir
Follow our classic recipe for kombucha or water kefir.
STEP 3: Make Secondary Flavored Cannabis Beverage
The recipe below creates a finished beverage with about 10mg THC per 8 ounce serving.
Cannabis Kombucha
Equipment
- swing top bottle(s)
- funnel
- muslin tea bag (small)
Ingredients
- 750 ml (24 fl. oz.) mature kombucha or water kefir
- 25 ml (5 tsp.) cannabis syrup recipe link above
- 10 g (about 1 inch) fresh ginger root OR
- 3-5 g hops flowers or pellets
Instructions
- With a funnel, add cannabis syrup to a clean glass bottle (either a swing top or one with a cap which can tighten.)
- Wash, peel (optionally), and slice ginger into matchstick size pieces and add to bottle. If using hops, add flowers or pellets to a small reusable tea bag. Use a chopstick to push tea bag into bottle.
- Top with plain kombucha or water kefir. Leave less than 1 inch (3cm) of head space in the neck of the bottle. Close tightly.
- Ferment 4 to 14 days, burping occasionally (over the sink) to release gas buildup.
- When you like the flavor and carbonation, move bottle to refrigerator.
- Before serving, gently rock (DO NOT SHAKE) the bottle by inverting it a few times. This will allow any sediment to be better incorporated into the beverage when you pour it.
- Serve chilled.
- Cannabis ingested via food can take a long time to metabolize, sometimes up to 2 hours. Enjoy responsibly and plan accordingly.
Initial Experiment
Kombucha (primary fermentation) with cannabis syrup
In order to test whether the fermentation affects THC content, I tried a scientific-ish experiment. I tasted a spoonful of cannabis syrup mixed in with regular kombucha, and then studied the effects. Then I tried an equivalent amount of syrup in the fermented-with-cannabis batch. The effects of the fermented batch were indeed more mellow. So it appears that the fermentation process reduces the THC content at least a little.
The effects of the cannabis when it’s been fermented in with the kombucha are noticeably more subtle than when consuming the syrup without fermentation. The finished kombucha has a really nice aroma (subtle terpenes), and is quite tasty. Many testers report that they couldn’t detect any flavor of cannabis. I’ll keep working on the recipe. Most would therefore argue that it’s not a good technique because it is loses potency during fermentation. That could well be true. I still enjoy drinking the kombucha and its light effects. I will continue the experimentation again using more and stronger syrup.
Always store scobys used in this recipe separately from other “non-cannabis” scobys. Best is to store them in their own jar (always at room temperature– never in the refrigerator!) in a little of the reserved liquid from the last batch you make. Keep a cloth lid on top of the jar to keep out flies and allow the scoby to continue to breathe. It doesn’t need much liquid to hang out– just enough to keep it submerged.
References:
- Meet the Cannabis Kombucha Guru, herb.co. Accessed Mar. 20, 2018
- Cooking with Cannabis: Delicious Recipes for Edibles and Everyday Favorites. Wolf, Laurie.
- How to Calculate Edible Potency, keytocannabis.com. Accessed Mar. 12, 2018.
- How to calculate THC dosage in recipes for marijuana edibles, thecannabist.co. Accessed Mar. 12, 2018.
- Dosing Homemade Cannabis, Cooking with Cannabis, Part 4. Leafly.com
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