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Controlling the temperature of your kombucha brew is the easiest ways to ensure that you bottle your kombucha when it is at its tastiest. The temperature of the brew is directly related to how long the brewing process takes.
It also impacts the health of the SCOBY. Brewing kombucha at too cold a temperature results in weak SCOBY growth, and weak flavor. It also makes your SCOBY susceptible to mold – your worst kombucha brewing enemy.
You will likely discover that there is a certain sweet spot in the brewing process at which time the kombucha is exactly to your liking – slightly tart, with a hint of sweetness. To find this sweet spot each time you brew requires that the fermentation process occurs at a consistent temperature.
A quality digital thermometer and taking the time to record the brew temperature at regular intervals will make sure your kombucha brewing process results in a delicious brew every time.
The SCOBY will be happiest and produce the best kombucha at its optimal temperature of between 78 and 82 degrees Fahrenheit. If you keep the room where your fermenter is located at that temperature, then you are all set.
However, if the room is much colder than that, it is best if you have a way to keep your brew warm.
There are a few ways of accomplishing that. You can purchase specially designed heating units designed for kombucha brewing. If they are within your budget, they work well.
The better ones (top two in the list below) even include a temperature control making them the ideal solution.
These fermentation brew heaters have excellent ratings from customers.
| Image | Title | Price | Prime | Buy |
|---|---|---|---|---|
| Top | Adjustable Kombucha Heat Mat - Bucha Brewers Kombucha Heating Wrap, Kombucha Warmer, Fermenter Heater | PrimeEligible | Buy Now | |
| Kombucha Heating Wrap - Black | PrimeEligible | Buy Now | ||
| Northern Brewer - FermoTemp Electric Fermentation Heater | Prime | Buy Now | ||
| kitchentoolz Waterproof Seedling Heat Mat Hydroponic Warm Heating Pad 3" x 20" with Adhesive Thermometer for Kombucha Brewing, Beer Brewing, Fermentation, Seedlings & Plant Germination (3" x 20") | PrimeEligible | Buy Now |
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
Prices pulled from the Amazon Product Advertising API on:We have found that the most inexpensive way to keep kombucha brewing at the proper temperature (and one that has worked for us for years) is something called a seedling warming mat. It is a plastic mat that is large enough to wrap about halfway around the fermentation jar and creates a small amount of heat. It will warm the brew evenly.
| Image | Title | Price | Prime | Buy |
|---|---|---|---|---|
| VIVOSUN Durable Waterproof Seedling Heat Mat Warm Hydroponic Heating Pad 10" x 20.75" MET Standard | PrimeEligible | Buy Now | ||
| MET certified Seedling Heat Mat, Seedfactor Waterproof Durable Germination Station Heat Mat, Warm Hydroponic Heating Pad for Indoor Home Gardening Seed Starter(10" x 20") | PrimeEligible | Buy Now | ||
| BN-LINK Durable Seedling Heat Mat Warm Hydroponic Heating Pad Waterproof 10" x 20.75" for Seed Starting Greenhouse and Germination | PrimeEligible | Buy Now | ||
| VIVOHOME 20W Waterproof Seedling Heat Mat for Seed Starting Propagation and Increase Germination Success 10 Inch x 20.75 Inch MET Safety Standard Certified | PrimeEligible | Buy Now |
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
Prices pulled from the Amazon Product Advertising API on:The only drawback we have found to using an inexpensive heater is that there is no easy way to control the temperature exactly. That is also true of some of the dedicated heaters above that wrap around the kombucha brewing jar.
However, by using an outlet timer, you can set the heating mat to go on and off at regular intervals. With a little experimentation, it is easy to control the kombucha brew within a couple of degrees.
We have recently discovered an easier way to keep our brew at the perfect brewing temperature during the cold months. The manufacturers of seedling mats sell thermostats that work well to keep the temperature perfectly in the correct range. The thermostat plugs into the power outlet and the heating mat plugs into the thermostat.
A temperature sensor probe is included that is affixed to the outside of the brewing jar. It senses the temperature of the jar and controls how much heat the heating mat puts out.
If you purchase or already own an inexpensive seedling heating mat, purchasing a thermostat insures that it is easy to keep the brewing temperature perfect.
Here are our picks for the top rated thermostats.
| Image | Title | Price | Prime | Buy |
|---|---|---|---|---|
| BN-LINK Digital Heat Mat Thermostat Controller for Seed Germination, Reptiles and Brewing Breeding Incubation Greenhouse, 40-108°F, 8.3A 1000W ETL Listed | PrimeEligible | Buy Now | ||
| VIVOSUN Digital Heat Mat Thermostat Temperature Controller 40–108 ºF for Seedlings, Germination, Rooting, Fermentation and Reptiles | PrimeEligible | Buy Now | ||
| ELECTECK Heat Mat Thermostat, Digital Controller for Seed Germination, Reptiles and Brewing, 41°F to 108 °F/ 5℃ to 42℃, 8.3A, 1000W, Black | PrimeEligible | Buy Now | ||
| Pymeter Digital Temperature Controller Dual Probe Reptile Thermostat Controlled Outlet Cooling Heating Pad Heat Mat Thermostat for Reptiles Homebrew Aquarium Greenhouse Terrarium Carboy Heater | PrimeEligible | Buy Now |
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
Prices pulled from the Amazon Product Advertising API on:By purchasing a thermostat-heating mat combo you can have your kombucha brewing at the perfect temperature with almost no effort! This is the method we now recommend!
| Image | Title | Price | Prime | Buy |
|---|---|---|---|---|
| Ohuhu Seedling Heat Mat 10" x 20.75" with Digital Seedling Heat Mat Thermostat Controller, Plants Hydroponic Heating Pad for Indoor Seedling and Germination | PrimeEligible | Buy Now | ||
| RIOGOO 10"x20.75" Seedling Heat Mat and Thermostat Controller 68-108°F Digital Thermostat Controller IP68 Waterproof (Heated mat+Thermostat Controller) | PrimeEligible | Buy Now | ||
| BN-LINK Durable Seedling Heat Mat Heating Pad 10" x 20.75" with Digital Thermostat Controller Combo Set Waterproof for Indoor Seed Starting and Plant Germination | PrimeEligible | Buy Now | ||
| VIVOSUN 10"x20.75" Seedling Heat Mat and Digital Thermostat Combo Set MET Standard | PrimeEligible | Buy Now |
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
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Hi there! I just bought a seedling heat mat + thermostat. Do you put the thermostat sensor directly into the brew, or do you tape it to the outside of your fermentation vessel? Thanks!
Hi Nikki and thanks for your comment. I would be hesitant to put anything metallic into brewing kombucha. Kombucha is quite acidic and would likely break down the metal probe over time. I recommend taping the probe to the side of the fermenter.
After it has been working for 24 hours, check the temperature of the brew with an instant read thermometer. Then you can adjust the thermostat temperature setting so that your brew is in the correct temperature range. It should work really well and insure that your brew is at the perfect temperature. Especially important if the room is cool! Happy brewing.
I am making my first batch of kombucha. I have a heat mat BUT it takes my kombucha to 82 degree’s farenhiet is this too high
Hi Paul. Thank you for your question. 82 degrees is only a little high–your kombucha should brew just fine. But, if you would like it to brew a little slower, here is the trick. Add a little bit more space between your kombucha brewing jar and the heat mat. In other words, don’t place the mat right against the glass. That will cool it down a bit. Happy brewing!
How do I keep kombucha brewing at 80°F in an apartment with no air conditioning during summer.
Hi Brad, that is a good question. If I understand you correctly, your apartment reaches temperatures over 85°F in the summer, or even hotter? At those temperatures, the kombucha will brew very quickly. You still may get good kombucha–you’d have to try it. I’d recommend checking the fermentation progress often. Perhaps you could use a swamp cooler idea–wrap a wet towel around your fermenter and let evaporation keep it a bit cooler. Good luck.
I brew in a half gallon mason (Ball brand) jar. Will the heat mat-thermostat combo work on that size of jar?
Also, is it ok/safe to place the thermostat probe under the heat mat on the outside of the jar, or does the probe need to be outside the mat taped to the glass?
Thinking there would not be a lot of extra room on the jar after placing the heat mat.????
1 gallon jar would be hard for me to manage with my small hands, & having to transport it to another room for fermenting.
Hi Marilyn and thanks for your great question. We sometimes brew in half-gallon jars as well. The heating mat solution can work, but it takes a bit of experimentation. You do need to have the temperature probe away from the heat mat so that it doesn’t get confused. What you do is keep part of the heat mat against the jar. The rest of it is flexed away from the side of the jar. The heat mat will still be able to warm the brew. The probe goes on the part of the jar that the heat mat is not touching. You will have to monitor it for a few days to get the set-up right, but once it is keeping the kombucha nicely heated, you won’t have to mess with it again. Have fun!
Thanks, that helps! ????