Fermentation Guides
Plain-English, source-cited guides to fermenting vegetables and brewing kombucha at home.
Start with the one rule that matters
Almost everything that goes wrong in vegetable fermentation traces back to salt measured by volume instead of weight. A "tablespoon of salt" can be anywhere from 15 to 25 grams depending on the brand and grind — enough spread to take a ferment from crisp and sour to soft and murky. The fix is the 2% salt-by-weight rule: weigh your shredded cabbage, multiply by 0.02, and add exactly that much salt. A 1,000 g batch of cabbage gets 20 g of salt, every time, with any salt brand. The sauerkraut salt guide walks through the math, plus the brine percentages for pickles and other ferments where you salt the water instead of the vegetable.
Kombucha runs on ratios and patience
Kombucha is the same idea with a different microbe. The first ferment (F1) is sweet tea — about 1 cup (~200 g) of sugar per gallon — plus 2 cups of starter liquid from the last batch, left alone for 7–12 days at 72–84°F. The second ferment (F2) is where flavor and fizz happen: bottle it with a little fruit or sugar and give it another 2–4 days sealed. The kombucha F1/F2 guide covers the timings, temperatures, and how to get carbonation you can rely on instead of flat one week and gushers the next.
Common questions
Do I need special equipment to start? No — a wide-mouth mason jar, something to keep the vegetables under the brine, and a scale that reads grams will make real sauerkraut. Airlock lids and glass weights make it more forgiving, and a crock makes sense once you're fermenting by the head of cabbage rather than the half. The supplies guide ranks what's worth buying at each stage.
When is the best time to ferment? Right now, if it's summer: July through September is peak season for cabbage and pickling cucumbers, and kraut started in high summer is ready for fall. Cooler kitchens in the 65–72°F range ferment slower but often taste cleaner — temperature changes the schedule, not the method.
How do I know it's working? Bubbles within a few days, brine that turns cloudy, and a smell that's sour but not foul. Vegetables that stay submerged under brine at the right salt percentage are doing exactly what a century of home fermentation says they should.