What’s The Ideal Temperature For Fermenting Foods?

“I recently started experimenting with fermenting foods at home, but I live in a colder area of Canada, and I’m struggling to get my ferments to turn out right. Sometimes they’re too slow, and other times they just don’t develop the right flavor. I think it might be something to do with the temperature. What’s the ideal temperature for fermenting foods, and do you have any tips on how I can keep things consistent when my kitchen temperatures are all over the place?”

Thanks so much, Sarah, Nova Scotia, Canada.

What’s The Ideal Temperature for Fermenting Foods?

Ah, Sarah, I totally get it! Temperature fluctuations can be a real headache, especially in colder climates. Fermentation has this perfect “sweet spot” that can be tricky to achieve consistently if your home temperature is bouncing all over the place. I’ll walk you through the best temperature ranges for different types of ferments, why temperature matters so much, and — probably what you’re looking for — some creative ways to keep things more stable without turning your house into a sauna.

Why Does Temperature Matter When Fermenting?

Fermentation is all about encouraging the right kinds of bacteria and yeasts to grow and do their thing. Temperature plays a huge role in this. Too warm, and you’ll end up with speed-racer fermentation, which can make your ferments overly sour or mushy. Too cold, and you might end up waiting forever for anything to happen — or worse, encouraging the wrong bacteria.

Here’s the science in simple terms: different kinds of bacteria thrive at different temperatures, but most of the beneficial ones we want for fermentation prefer a comfortable middle range. Keeping that range steady is key to getting consistent results.

The Ideal Temperature for Different Types of Ferments

Okay Sarah, here’s where it gets interesting. Not all ferments are created equal, and the ideal temperature can change depending on what you’re fermenting. Let’s break it down by a few of the main types of fermentation you might be doing:

1. Vegetable Ferments (like sauerkraut or kimchi)

The sweet spot for veggie fermentation tends to be between 65°F and 75°F (about 18°C to 24°C). If you can get and keep your kitchen within this range, you’ll have happy ferments! At this temperature, lactic acid bacteria (the good guys) grow steadily and give you that signature tangy flavor without making your veggies too soft or slimy.

If the temperature dips below 60°F (16°C), things might grind to a halt, while going over 80°F (27°C) can make things progress too quickly, often leaving you with overly sour or mushy cabbage.

2. Fruit Ferments (like fermented fruits or kombucha)

Fruit tends to need a little bit more warmth — 70°F to 80°F (21°C to 27°C) is generally the best range. Why? Fruits have more natural sugars than veggies, and keeping the temperature on the higher end helps the yeast and bacteria work through those sugars efficiently, creating a nice, bubbly ferment with balanced sweetness and tang.

3. Sourdough

Sourdough is a bit greedier in terms of warmth. Ideally, sourdough likes a temperature range between 75°F and 85°F (24°C to 29°C). Over 85°F can make things rise too fast, which leads to a loss of flavor complexity.

If you’re working with cooler temperatures like the ones in Nova Scotia, you might need to give your dough a little extra warmth to get that perfect rise (we’ll get to tricks for keeping the temp steady in a bit).

4. Yogurt

Yogurt is more of a hot-blooded beast — ideally, it needs to sit between 110°F and 115°F (43°C to 46°C) for at least several hours to properly culture. Since this is way warmer than most other ferments, you’ll usually need some external help maintaining this temperature, which we’ll also chat about later. You don’t want it to be too hot though — more than 120°F (49°C) and you risk killing off the good bacteria entirely.

Why Colder Temperatures Can Slow Everything Down

Sarah, one thing you might be experiencing in Nova Scotia is cold-induced “ferment fatigue.” Lower temperatures below that optimal range can slow the process, making your ferments take significantly longer to develop. Sometimes, it can even stop the fermentation process altogether. For vegetable ferments, if you’re in a kitchen that frequently drops below 65°F (18°C), you might notice a lackluster or stalled ferment, like you mentioned.

This is because lactic acid bacteria, which are responsible for the magic of fermentation, get sluggish in cooler temps. They work best when they’re cozy, and cold temps can keep them from thriving. It doesn’t mean your ferment is doomed; it just means you might need more patience — or a strategy for warming things up.

On the Flip Side: What Happens If It’s Too Warm?

If you’re lucky enough to have a warm kitchen all year round, fermentation might move too fast. That could leave your fermented foods tasting overly sour, bitter, or just off. Texture-wise, an overly warm ferment can also turn slimy. And I’m sure no one’s excited about a mushy batch of sauerkraut after days of waiting!

In warm weather (or if your heating system cranks up in the winter), it may be best to keep your ferments somewhere cooler like a basement, or even your garage if it stays in that magic range for whatever you’re fermenting.

Helpful Tips for Controlling Fermenting Temperatures

If your kitchen doesn’t sit in the ideal range naturally, don’t stress. There are little hacks you can use to keep things on track and avoid those frustrations you’re experiencing, Sarah!

1. Wrap Your Jars in Towels

If you’re fermenting in cooler temperatures, something as simple as wrapping your jars in a towel can help keep the temperature more stable. This insulates them a little, protecting them from quick dips in room temperature. Bonus: it’s one less jar sticking out on your kitchen counter!

2. Use a Heating Pad for Controlled Warmth

If you’ve got much colder conditions like October-to-April in Nova Scotia, place your jars on a low-heat heating pad. Some pads let you control the exact settings, so you can keep things steady without overheating! Just make sure it’s set low and doesn’t get too hot for your ferment.

3. Try a Water Bath Method

If you can, fill a cooler with warm water and tuck your fermenting jars inside. No need to fully submerge them, just up to the lid rings. This balances the temperature around them and keeps your ferments toasty even when the house is cool. Just make sure to refresh the water to keep it at the right temperature.

4. Move Your Ferments Around the House

In cooler weather, try moving your ferment to the warmest part of your home. For some people, this might be on top of the refrigerator or close to a water heater. A bit inconvenient? Sure. But worth it for happy ferments! My sauerkraut has spent many winters chilling on a cozy fridge top.

Signs Your Ferment Isn’t Enjoying the Temperature

If your ferment is on a temperature strike, it’ll tell you, Sarah! Here are a few signs your ferment might not be loving the temp:

• No bubbles: Bubbles are a great indicator that fermentation is happening. No bubbles? Could be too cold.
• Off smell: A healthy ferment will have its own funky but pleasant aroma. If it smells off (think rotten eggs), your temperature may have gotten too high, letting bad bacteria grow.
• Slow progress: If your ferment is taking way longer than expected, it might just be too chilly for those bacteria to do their best work.
• Weird textures: Too warm? You might end up with slimy or mushy veggies or fruits.

Extended Cold Weather? Try This…

Sometimes, especially in places like Nova Scotia, you’re looking at months of chilly weather, and walking through the house balancing jars on heating pads isn’t ideal. If you face long cold spells consistently, consider investing in a fermentation chamber. These little units allow you to set the precise temperature inside — a game-changer for anyone trying to ferment in less ideal conditions like your colder kitchen, Sarah!

Final Thoughts…

Sarah, thanks for your question, because it’s one that a lot of folks struggle with! Temperature is such a critical piece of fermentation. Get it right, and you’ll have delicious, bubbly, and flavorful ferments that you’ll love. Stray too far in either direction, and you run into those issues you’ve been experiencing. By sticking to a temperature range that is ideal for whatever you’re fermenting and taking some simple steps to adjust, your future ferments will be everything you’re hoping for.

Happy fermenting, Sarah — and keep warm up there!