Last updated: August 23, 2026
Fermenting is the one preservation method that needs no canner, no dehydrator and no electricity. A crock or a jar, vegetables, salt and a place in the house that stays cool is the entire equipment list, which is why it was the standard way to get cabbage and cucumbers through a winter long before anyone owned a freezer.
It is also the method that makes people most nervous, because nothing gets heated and the jar sits on the counter for weeks doing something visibly alive. The nervousness is reasonable and the answer is not intuition, it is following tested guidance on salt, submersion and temperature. Get those three right and the ferment protects itself.
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Quick Answer
How do you ferment vegetables?
- Use a tested ratio. For sauerkraut the NCHFP works in 5 pound batches of cabbage with 3 tablespoons of canning or pickling salt per batch.
- Size the vessel to the load. The NCHFP states a 1 gallon container is needed for each 5 pounds of fresh vegetables.
- Keep everything submerged. The NCHFP says cabbage and cucumbers must be kept 1 to 2 inches under brine while fermenting.
- Hold the temperature. The NCHFP notes kraut is fully fermented in about 3 to 4 weeks at 70 to 75 degrees F, and 5 to 6 weeks at 60 to 65 degrees F.
Bottom line: weigh the salt, keep the vegetables under the brine, and let temperature set the clock instead of guessing.
What Fermenting Actually Does
Salt draws water out of the vegetables and creates a brine that favors the bacteria you want while holding back the ones you do not. Those bacteria convert sugars into acid, the acid drops the pH, and the finished product keeps because of that acidity rather than because of heat. The NCHFP describes salt in fermented sauerkraut as vital to safety and texture, not only flavor.
That is why fermenting is not a place for improvisation. A guessed salt quantity or vegetables left poking above the brine changes the conditions the method depends on, and the result is soft, moldy or simply spoiled rather than merely disappointing.
Salt Is the Safety Step
Use canning or pickling salt, which dissolves cleanly and carries no additives. The NCHFP sauerkraut method works in 5 pound batches of shredded cabbage with 3 tablespoons of salt added per batch, and if the juice does not cover the cabbage it directs you to add a boiled and cooled brine of 1 1/2 tablespoons of salt per quart of water.
Why Table Salt Causes Trouble
Iodized table salt and salts with anti caking agents can cloud the brine and darken the vegetables. The result is usually cosmetic rather than dangerous, but since canning and pickling salt costs very little there is no reason to introduce the variable. We compare the options in canning salt against pickling salt.
Weigh, Do Not Eyeball
A tablespoon of one salt is not the same weight as a tablespoon of another, because crystal size differs. Weighing the vegetables and the salt is what makes a batch repeatable, and it is the single habit that separates people who ferment occasionally from people who ferment reliably. Our page on sauerkraut brine ratios works through the arithmetic.
Containers, Covers and Weights
The NCHFP states that a 1 gallon container is needed for each 5 pounds of fresh vegetables, so a 5 gallon stone crock suits roughly 25 pounds of cabbage or cucumbers. Stone crocks, food grade plastic containers and glass all work. The NCHFP warns against letting vegetables touch non food grade plastics and says not to use garbage bags or trash liners.
For covers and weights the NCHFP describes a dinner or glass pie plate slightly smaller than the container opening, weighted down with 2 to 3 sealed quart jars filled with water, or a large clean food grade plastic bag holding 3 quarts of water with 4 1/2 tablespoons of salt dissolved in it. The container opening then gets covered with a clean, heavy bath towel.
If you want purpose made weights for mason jars
Keeping Everything Under the Brine
This is the rule that decides whether you get sauerkraut or a science experiment. The NCHFP says cabbage and cucumbers must be kept 1 to 2 inches under brine while fermenting. Anything that floats into the air gap is exposed to oxygen, and that is where surface yeasts and mold get started.
Airlock lids handle the same problem from the other direction, letting carbon dioxide escape without letting air back in. They do not replace a weight, they work alongside one, and they cut down on the daily skimming that an open crock needs. Our guide to fermentation lids covers the styles that actually seal.
If your jars keep bubbling over the rim
Temperature Sets the Clock
Fermentation speed is a temperature question, not a calendar question. The NCHFP states that at 70 to 75 degrees F kraut will be fully fermented in about 3 to 4 weeks, while at 60 to 65 degrees F fermentation may take 5 to 6 weeks. Below 60 degrees F it notes fermentation may not occur at all, and above 75 degrees F the kraut may become soft.
That range is why the basement stairs, a north facing pantry or an unheated back room are the classic fermenting spots. A kitchen counter next to a sunny window swings too far in both directions, and the batch pays for it in texture.
Vessel Sizes and What They Hold
Matching vessel to load keeps the brine deep enough and leaves room for the foam. The table uses the NCHFP sizing rule of 1 gallon per 5 pounds of fresh vegetables.
| Vessel | Fresh vegetables it suits | Weighting approach | Best for |
|---|---|---|---|
| Quart mason jar | Roughly a single small head trimmed down | Glass weight plus airlock lid | Test batches, one vegetable at a time |
| Half gallon jar | Small batch, easy to fit in a cupboard | Glass weight, check level daily | Kitchen scale ferments, pickles |
| 1 gallon container | 5 pounds per the NCHFP sizing rule | Plate plus sealed water filled jars | A single cabbage harvest |
| 5 gallon stone crock | About 25 pounds of cabbage or cucumbers | Plate and jars, or a water filled brine bag | Whole row of the garden at once |
Container sizing, the weighting methods and the brine bag described above come from the NCHFP guidance on suitable containers, covers and weights for fermenting food.
What the Surface Is Telling You
A white, wrinkled film on the brine is usually kahm yeast, which is unpleasant rather than dangerous and gets skimmed off. Fuzzy growth in colors, blue, green, black or pink, is mold, and mold on a ferment is a different conversation with a different answer. We separate the two in kahm yeast against mold.
Bubbling, cloudy brine and a sour smell are all normal and expected. A ferment that smells putrid rather than sour, or one where the vegetables have gone slimy and the brine has turned ropey, goes in the compost. Do not taste your way through a decision like that.
Frequently Asked Questions
How much salt do I use per pound of vegetables? Follow a tested recipe rather than a general rule. For sauerkraut the NCHFP works in 5 pound batches of cabbage with 3 tablespoons of canning or pickling salt each, and adds a brine of 1 1/2 tablespoons of salt per quart of water if the juice does not cover the cabbage.
How long does fermentation take? Temperature decides. The NCHFP gives about 3 to 4 weeks at 70 to 75 degrees F for kraut and 5 to 6 weeks at 60 to 65 degrees F, and notes that fermentation may not occur below 60 degrees F.
What container should I use? Stone crocks, glass and food grade plastic. The NCHFP states a 1 gallon container is needed for each 5 pounds of fresh vegetables, and warns against non food grade plastics, garbage bags and trash liners. Our crock guide covers water seal designs.
Do I need special equipment to start? No, a jar, salt and something to hold the vegetables under the brine covers a first batch. Weights and airlock lids make it easier rather than possible, which is why a starter fermentation kit is the usual second purchase.
Can I can my fermented vegetables afterward? Sauerkraut can be heat processed using tested processing times, which the NCHFP publishes by pack style and elevation. Canning changes the texture and kills the live cultures, so many people keep finished kraut refrigerated instead, which the NCHFP notes keeps tightly covered for several months.
The Bottom Line
Fermenting vegetables is three numbers and one habit: the salt in a tested recipe, the 1 gallon per 5 pounds vessel rule, the 1 to 2 inches of brine over the vegetables, and checking the level every day. The NCHFP publishes all of them, and the batches that fail are almost always the ones that improvised on one. Ready to set up properly? Our fermentation kit guide covers what a first setup actually needs, and fermentation weights is the single accessory that prevents the most common failure.