How Long Should I Let My Vegetables Ferment?

There is no hard and fast rule for how long to culture vegetables; there are many factors to consider when deciding to move vegetables to cold storage. Time, temperature and ingredients all have a significant impact on culturing. Before adding salt and, if desired, a starter, to your prepared vegetables, you'll want to consider decisions about culturing time and temperature.


As with most culturing, lacto-fermentation happens faster at warmer temperatures. In our fast-paced society, it may seem desirable to speed things along in order to enjoy ferments sooner, but this assumption isn’t necessarily true.

Culturing is a complex process. A variety of microbes are involved, and they all prefer different temperatures. Experts generally recommend a slow, cool ferment at temperatures as low as 50°F (10°C). At temperatures this low, the process can take as long as 6 months or more, which is longer than many people want to wait.

Luckily, fermentation that occurs at 60-70°F (15-20°C) is slow enough to develop many of the complex flavors and retain texture, while moving fast enough for you to enjoy the ferments within 2-6 weeks. A cooler, slower  fermentation seems to last longer in cold storage as well.

When temperatures exceed 70°F (20°C), fermentation happens quickly. The bacteria that feed on pectin are more active, causing vegetables to break down into softer textures. The flavor is sharper, rather than tangy. Water also evaporates faster, so be sure to monitor the level of brine in the vessel. When moved to cold storage, the ferments may not last as long.


As the vegetables begin to ferment, the bacteria feed on sugars in the produce. The breakdown of the sugars changes the flavor from sweet to tangy and tart. The process doesn’t seem to be linear. For instance, garlic starts with its usual bite to becoming intensely hot after a week or two of fermentation. Then it begins to mellow and becomes creamy and almost sweet. Cabbage develops a tart flavor and a sharp crunch. A long-fermented kraut becomes quite mellow and begins to soften.

The only way to really know when a ferment is ready is to taste it. While there is much debate on appropriate fermentation times, the best time to move a ferment to cold storage is when it tastes pleasant to the people who will be consuming. After all, what good is a ferment that no one will eat!

Understanding the factors that influence fermentation will make it easy to decide how to transform foods into delicious, probiotic-rich ferments.


You can find dozens of recipes for fermenting vegetables in our natural fermentation recipe collectionour free Lacto-fermentation eBook, and in other books on fermentation.