A Guide to using a Heat Mat for Fermentation

Fermentation is a delicate process. The right temperature can make the difference between perfectly tangy sauerkraut or kefir and a slow, inconsistent batch. Using a Symbiota heat mat with a thermostat controller helps you maintain consistent warmth, giving your ferments the optimal environment to thrive.

Here’s how to get the most out of your setup.

Why Temperature Matters in Fermentation

Fermented foods like kimchi, sauerkraut, kefir, and hot sauces rely on live cultures. These microbes are temperature sensitive:

• Too cold: Fermentation slows, textures remain firm, and flavours may be bland.
  
  
• Too hot: Cultures can over-ferment, producing off flavours, excessive fizz, or a mushy texture.
  
  

A heat mat with a thermostat controller allows you to set a precise target temperature, keeping your ferment consistent, predictable, and delicious.

Step 1: Set Up Your Heat Mat

1. Place your heat mat on a flat, stable surface, away from water.
2. Plug it and turn the thermostat on, this lets you regulate temperature accurately.
3. Position your fermentation vessel (jar or crock) directly on the mat. 
4. To maximise the heat of the mat for thermophilic yogurts, you can wrap the ferments in a towel or even wrap the mat around the jar. 

Tip: Avoid direct sunlight or drafts, which can interfere with consistent heating.

Step 2: Choose the Right Temperature

Different ferments have different ideal ranges:

Set your thermostat controller to the mid-range for your ferment, then adjust based on how quickly your ferment develops.

For better results: use a thermometer sticker on your jar to note the temperature of your ferment. 

Note: Your heat pad will be countering environmental temperatures. So if your room temperature is 18°C but you require your ferment to be 22°C, you will need to set the heat mat at a higher temperature (likely 26-28 degrees) to account for loss of heat during heat transfer and the cooling environmental temperature. See the table below

Step 3: Monitor & Adjust

1. Check your ferment daily: Look for bubbles, smell, and texture.
   
   
2. Adjust the thermostat if needed: If the ferment is too slow, increase the temperature slightly. If it’s over-fermenting, lower the heat or remove from the mat.
   
   
3. Keep a log: Note temperature, time, and observations for future reference -  this helps you fine-tune for perfect results every time.
   
   

Step 4: Maximise Heat Mat Efficiency

• In winter, wrap ferments with towels to hold heat in
  
  
• Group similar ferments together on one mat for consistent temperature distribution.
  
  
• Use a thermometer in the ferment or a temperature sticker on the fermentation vessel to double-check that the thermostat matches the internal temperature of your food.
  
  

Step 5: Safety Tips

• Never place the mat in water.
  
  
• Use a temperature controller rated for the mat to prevent overheating.
  
  
• Keep cords away from high-traffic areas.
  
  
• Regularly inspect the mat for wear or damage.
  
  

Bonus Tips for Fermentation Success

• Patience pays off: Even with optimal heat, some ferments take longer — taste test rather than relying solely on days.
  
  
• Combine with ambient knowledge: Room temperature, season, and the type of produce all affect fermentation.
  
  
• Keep notes: Over time, you’ll learn the perfect timing and temperature for each recipe.
  
  

A Symbiota heat mat with a thermostat controller transforms your home fermentation by giving you consistent, controlled warmth. With careful monitoring and the right settings, your kimchi, sauerkraut, kefir, and hot sauces will ferment perfectly every time, bringing tangy, gut-friendly flavours straight to your kitchen.

Start small, track your results, and watch your ferments flourish. 

Heat Mat Settings Reference Table for Fermentation (Guideline)

Ambient Temp (°C)	Target Temp (°C)	Recommended Mat Setting (°C)
15	18	22–23
15	19	23–24
15	20	24–25
15	21	25–26
15	22	26–27
15	23	27–28
15	24	28–29
16	18	22–23
16	19	23–24
16	20	24–25
16	21	25–26
16	22	26–27
16	23	27–28
16	24	28–29
17	18	22
17	19	23
17	20	24
17	21	25
17	22	26
17	23	27
17	24	28
18	18	21–22
18	19	22–23
18	20	23–24
18	21	24–25
18	22	25–26
18	23	26–27
18	24	27–28
19	18	22
19	19	22–23
19	20	23–24
19	21	24–25
19	22	25–26
19	23	26–27
19	24	27–28
20	18	21–22
20	19	22–23
20	20	23–24
20	21	24–25
20	22	25–26
20	23	26–27
20	24	27–28
21	18	21
21	19	22
21	20	23
21	21	23–24
21	22	24–25
21	23	25–26
21	24	26–27
22	18	21
22	19	22
22	20	23
22	21	23–24
22	22	24
22	23	25
22	24	26
23	18	21
23	19	22
23	20	23
23	21	23–24
23	22	24
23	23	25
23	24	25–26
24	18	21
24	19	22
24	20	23
24	21	23–24
24	22	24
24	23	25
24	24	25–26