Kohlrabi in 6% brine
10.0 days at 68 °F · pH target 3.50 · outside typical range
Brine calculator
For submerged vegetables (cucumbers, peppers, cauliflower, garlic scapes). Salt mass is expressed as a percentage of water mass — NCHFP convention.
1 L of water ≈ 1 kg. 3.5% brine = 35 g salt per litre.
About Kohlrabi
Kohlrabi — the German turnip — is a Brassica oleracea cultivar grown for its bulbous, swollen stem rather than its root. Crisp, mild, and slightly sweet raw, it ferments into a snappy, slightly tangy pickle that retains its crunch for months. Common in Czech, German, and Korean cooking; in kimchi tradition it appears as a component in mixed-vegetable variants. The white-skinned variety ferments faster than purple; either works.
Fermentation data
- Default salt
- 2.5%(you are viewing 6%)
- Salt range
- 2–3%
- Time at 68°F
- 10.0 days
- pH target
- 3.50
- Water content
- 90%
- Preferred styles
- brine pickle, kimchi component
Note: 6% is outside the typical brine range for Kohlrabi (2–3%). The recommended default is 2.5%. View 2.5% brine + Kohlrabi.
Technique
Peel the tough outer skin (it can be thick — peel deep enough to remove all woody fibers). Cut into 1-cm matchsticks or 5-mm rounds. Pack into a jar with one bay leaf, a teaspoon of caraway seed, and a thin slice of horseradish or one crushed garlic clove per quart. Cover with 2.5% brine, weight, leave 1 inch headspace. Ferment 7-14 days at 65-72°F. Done when fully sour but still crisp at the bite. Refrigerate; will hold 4+ months.
Brine notes at 6%
60g salt per 1L water. Almost too salty to eat directly — the finished product (fish sauce, garum) is used as a seasoning, not consumed neat. For vegetable ferments, only use in tropical-climate long ferments where 5% is inadequate. Noma Guide: 6% used for some of their rapid-ferment glass-jar garums.
What a 6% brine does for Kohlrabi
A 6% brine is 60 g of salt in every litre of water. That salt pulls moisture out of the kohlrabi by osmosis and, more importantly, tilts the jar in favour of salt-tolerant Lactobacillusover the spoilage microbes that can't handle it. A stronger brine ferments more slowly, keeps the vegetable firmer and crunchier, and stores longer; a weaker one ferments faster and softer.
Safety: Preserving brine. Fermentation will be very slow; flavour strongly salty. Used for long-keeper pickles, olive cures and fish-sauce bases. Target pH once soured: ~3.50 (below pH 4.6 is the fermented-vegetable safety threshold).
Brine recipe for a 1-litre jar
| Water | 1 L (1000 g) |
| Salt (6%) | 60 g |
| Kohlrabi, packed | ~650 g |
Dissolve the salt fully, cool the brine to room temperature, pack the kohlrabi, and pour over until submerged. Use the calculator above to scale to your exact jar or crock.
How long Kohlrabi takes at your kitchen temperature
Kohlrabi takes about 10 days in a 6% brine at the 68°F baseline. Fermentation speeds up as the room warms and slows as it cools — the days below are that baseline scaled by temperature:
| Kitchen temp | Approx. days | What to expect |
|---|---|---|
| 55°F (12.8°C) | 26.9 d | slow, clean |
| 60°F (15.6°C) | 19.2 d | classic range |
| 64°F (17.8°C) | 14 d | classic range |
| 68°F (20°C) | 10 d | baseline |
| 72°F (22.2°C) | 8 d | fast — check daily |
| 76°F (24.4°C) | 6.3 d | fast — check daily |
Temperature multipliers after the Noma Guide to Fermentation (pp. 53–57) and Katz, The Art of Fermentation (ch. 3). Below ~50°F ferments effectively stall; above ~82°F, mould and kahm yeast rise fast — taste and refrigerate early.
Kohlrabi in 6% brine — FAQ
How much salt do I need for a 6% brine?
Dissolve 60 g of non-iodised salt (fine sea or pickling salt) in every 1 litre (1000 g) of water — that is 6% by weight. For a partial jar, scale it with the calculator above; the ratio stays the same.
How long does Kohlrabi take in a 6% brine?
About 10 days at the 68°F baseline. It runs slower in a cool room (~19.2 days at 60°F) and faster when it's warm (~6.7 days at 75°F). Start tasting from day 7 and refrigerate once it's as sour as you like.
Is a 6% brine strong enough and safe?
Preserving brine. Fermentation will be very slow; flavour strongly salty. Used for long-keeper pickles, olive cures and fish-sauce bases. As it ferments, kohlrabi should drop to about pH 3.50 — comfortably under pH 4.6, the acidity threshold the NCHFP and FDA treat as safe for fermented vegetables.
Why keep the kohlrabi under the brine?
Under the liquid the environment is oxygen-free, which is exactly what the Lactobacillus you want thrives in and what surface moulds and kahm yeast cannot tolerate. Anything poking above the brine is at risk — weigh the vegetables down so everything stays submerged.
Is cloudy brine or a white film normal?
Cloudy brine and a little sediment are normal signs of an active lacto-ferment. A thin, flat white film on the surface is usually kahm yeast — harmless; skim it off. Only fuzzy, raised, or blue/green/black growth is mould, in which case discard the batch.
Explore other brine concentrations for Kohlrabi
- 2.5% — lightly-salted vegetable brine
- 3% — standard half-sour brine
- 3.5% — NY deli half-sour
- 5% — full-sour / long-ferment brine
- 6% — fish sauce / garum base (current)
Sources
- Katz — The Art of Fermentation (p. 99, Brassicas)
- NCHFP (UGA) — Fermented and Pickled Products
- Linda Ziedrich, The Joy of Pickling (3rd ed., 2016)
For educational use only. Consult your local food safety authority for commercial production.
The kit for fermenting Kohlrabi
A short, honest kit for lacto-fermentation. The scale is the one that matters most — everything here is by weight.
- Digital kitchen scale (0.1 g)Salt % is by weight, not volume — a 0.1 g scale is what makes the math above accurate.View on Amazon →
- Glass fermentation weightsKeep vegetables submerged under the brine line so they ferment safely without mould.View on Amazon →
- Airlock fermentation lidsLet CO₂ escape while keeping oxygen out — wide-mouth lids that fit standard jars.View on Amazon →
- Wide-mouth mason jarsThe workhorse vessel for kraut, kimchi and brine pickles — 1 qt and ½ gal sizes.View on Amazon →
- Pickling / fine sea saltPure salt with no iodine or anti-caking agents, which can cloud brine and inhibit fermentation.View on Amazon →
- Stoneware fermentation crockFor scaling past the jar — a water-sealed crock for 5 L+ batches with built-in weights.View on Amazon →
As an Amazon Associate, Fermentcalc earns from qualifying purchases at no extra cost to you. More on how this is funded.