Kohlrabi Kimchi

If you love the bold, garlicky punch of traditional Korean kimchi but crave an unyielding, crisp texture, kohlrabi is your dream vegetable. This brassica transforms effortlessly under the power of lacto-fermentation, yielding crunchy cubes of spicy, savory goodness reminiscent of classic radish kkakdugi. With just a handful of pantry staples and a clean glass jar, you can master this refreshing kohlrabi kimchi recipe in under an hour of active prep time.

Why Kohlrabi Is Great for Kimchi

In traditional Korean cuisine, kkakdugi is made using Korean radish (mu), a dense, sweet, and pungent root. While daikon and Korean radish perform admirably, they tend to soften after several weeks of fermentation, releasing vast amounts of water that can dilute your brine.

Kohlrabi (Brassica oleracea Gongylodes Group) is structurally unique. Because it is a swollen stem that grows entirely above ground rather than a true taproot, its cellular walls are reinforced with a dense matrix of cellulose and pectin. This structural integrity means kohlrabi kimchi maintains an audible, satisfying crunch even after sitting in your refrigerator for months.

Flavor-wise, kohlrabi offers a natural, mild sweetness paired with a subtle, peppery turnip note. That inherent sugar feeds the beneficial lactic acid bacteria during fermentation, while the sweetness balances the intense heat of Korean chili flakes and the deep umami of fermented fish sauce. If you have previously made tangy fermented kohlrabi sauerkraut or vinegar-brined kohlrabi pickles, you will find that kimchi introduces a completely different dynamic: it is less sour, substantially more aromatic, and layered with rich, savory undertones.

Ingredients for Kohlrabi Kimchi

A successful batch relies on balancing salt, aromatics, heat, and umami. The ingredients below yield roughly one quart (1 liter) of finished kimchi.

Primary Produce

Kohlrabi: 2 pounds (900 g), weighed after trimming. Look for small to medium bulbs (about tennis-ball sized), which are juicier and far less fibrous than massive, overgrown specimens. Raw kohlrabi provides incredible nutritional perks; if you are curious about the raw root’s vitamin and antioxidant profile, read about kohlrabi juice benefits to see why this vegetable is an absolute powerhouse.
Scallions (Green Onions): 4 to 5 stalks, sliced into 1.5-inch (4 cm) lengths.
Asian Pear or Sweet Apple: 1/4 of a medium fruit, peeled and grated (this provides fructose to kickstart fermentation and mellow the chili).

The Salting Agent

Coarse Sea Salt or Kosher Salt: 2 tablespoons (30 g). Avoid iodized table salt or salts with anti-caking agents, as they can inhibit bacterial growth and create a cloudy, off-flavored brine.

The Seasoning Paste

Gochugaru (Korean Red Pepper Flakes): 3 to 4 tablespoons (20 to 28 g). Gochugaru is non-negotiable; standard cayenne or crushed red pepper flakes are much too sharp and lack the smoky, fruity, sun-dried flavor profile essential to kimchi.
Fresh Garlic: 5 to 6 cloves, finely minced or grated.
Fresh Ginger: 1 tablespoon (15 g), peeled and finely grated.
Fish Sauce: 2 tablespoons (30 ml). High-grade fish sauce brings necessary glutamate for savory depth. (For a vegan version, substitute equal parts high-quality tamari, regular soy sauce, or a vegan fish sauce made from kelp and mushroom broth).
Granulated Sugar or Honey: 1 teaspoon (5 g), to balance acidity.

Salting the Kohlrabi

Salting is the foundational step of this kohlrabi kimchi recipe. It performs two critical roles: drawing out excess moisture through osmosis so the final product remains crisp, and establishing a baseline salinity that discourages spoilage bacteria while inviting lactic acid bacteria to thrive.

Peel thoroughly: The fibrous outer skin of kohlrabi never softens, even after prolonged fermentation. Use a sharp chef’s knife rather than a swivel peeler to carve away the tough green or purple skin and the woody fibrous layer just beneath it. You should be left with translucent, ivory-colored flesh.
Cube the flesh: Cut the peeled bulbs into bite-sized cubes, roughly 3/4-inch (2 cm) square. Uniformity ensures even salting and consistent fermentation.
Salt and toss: Place the diced kohlrabi into a large mixing bowl. Sprinkle the 2 tablespoons (30 g) of coarse salt evenly over the cubes. Use your hands to toss the pieces, ensuring every surface is coated.
Rest: Let the bowl sit at room temperature for 45 to 60 minutes. Toss the mixture once or twice halfway through.
Drain: By the end of the hour, a significant pool of liquid will sit at the bottom of the bowl, and the cubes will look slightly glossy. Pour the kohlrabi into a colander. Do not rinse the kohlrabi with water. Simply let it drain thoroughly for 10 minutes. A light cling of residual salt is vital for preserving the vegetable during fermentation.

Making the Paste

While the salted kohlrabi drains, prepare your seasoning paste. Traditional whole-cabbage kimchi often uses a cooked sweet rice flour porridge to bind the paste, but for diced root vegetables like kohlrabi, a direct seasoning mix works exceptionally well.

In a medium bowl, combine:

3 to 4 tablespoons (20 to 28 g) gochugaru
5 to 6 cloves minced garlic
1 tablespoon (15 g) grated ginger
1/4 grated Asian pear or apple
2 tablespoons (30 ml) fish sauce (or vegan substitute)
1 teaspoon (5 g) sugar

Stir the mixture thoroughly with a spoon. Let the paste rest for 10 minutes. This resting phase allows the dry flakes of gochugaru to hydrate, pulling moisture from the pear, garlic, and fish sauce to form a thick, deep-crimson paste with an aromatic, spicy scent.

Once rested, transfer the drained kohlrabi cubes and sliced scallions into the bowl with the paste. Put on a clean kitchen glove (gochugaru can easily stain fingers and irritate bare skin) and vigorously massage the paste into the kohlrabi until every individual cube is thoroughly coated.

Packing and Fermenting

Proper packing prevents unwanted mold and allows anaerobic bacteria to establish an acidic, safe environment.

Choose your vessel: Use a wide-mouth 1-quart (1-liter) glass canning jar. Ensure the jar and its lid are washed thoroughly with hot, soapy water and dried completely. Sterilization in boiling water is not mandatory for lacto-fermentation, but immaculate cleanliness is essential.
Pack tightly: Add the spiced kohlrabi to the jar a few spoonfuls at a time. Press down firmly with clean fingers, a wooden spoon, or a cabbage tamper to force out trapped air pockets. Pack the jar until the contents sit roughly 1 to 1.5 inches (2.5 to 4 cm) below the rim. This headspace is critical: as bacteria generate carbon dioxide, the liquid will swell.
Seal: Screw the lid on snugly, but avoid wrenching it shut with excessive force.
Ferment at room temperature: Place the jar out of direct sunlight in a location that stays between 65°F and 72°F (18°C and 22°C).
Burp daily: If you are using a standard Mason jar lid without an airlock valve, “burp” the jar once or twice daily by briefly unscrewing the lid just until you hear a hiss of escaping gas, then retightening it. Bubbles will soon begin forming along the glass, and the surface liquid will rise slightly.

Fermentation timing depends on room temperature:

Warm environments (70°F to 75°F / 21°C to 24°C): Active fermentation occurs quickly. The kimchi is often pleasantly tangy within 24 to 48 hours.
Cool environments (60°F to 65°F / 15°C to 18°C): The process moves slower, taking 3 to 5 days to reach an optimal, lively sourness.

When It’s Ready and How to Store It

Begin tasting your kohlrabi kimchi after 24 to 36 hours. Unscrew the jar, press a clean fork into the cubes to sample a piece, and check the balance. When ready, it should taste distinctly effervescent, slightly sour, garlicky, and unapologetically crunchy.

Once the flavor reaches your preferred balance of acid and heat, move the jar to the refrigerator. Cold temperatures (36°F to 40°F / 2°C to 4°C) dramatically slow microbial activity, allowing flavors to meld together without turning aggressively sour. Kohlrabi kimchi will maintain its phenomenal texture in cold storage for up to 6 months. Always use clean utensils when removing portions from the jar to keep the remaining batch fresh.

If you bought a surplus of bulbs from the farmers market to make multiple batches over the coming weeks, be sure to read our detailed guide on how to store kohlrabi to keep your raw stock crisp in the meantime.

Safety Notes

Lacto-fermentation is historically one of the safest methods of home food preservation. As beneficial lactic acid bacteria consume natural sugars, they generate lactic acid, rapidly dropping the pH of the vegetable below 4.6. This acidic environment inhibits harmful pathogens.

For verified home fermentation and food preservation principles, consult resources provided by the National Center for Home Food Preservation.

To guarantee safety in every batch, keep the following rules in mind:

Watch the mold: Fermentation requires an anaerobic (oxygen-free) environment. If bits of kohlrabi float above the brine and encounter trapped air, fuzzy white, green, or black mold can develop. If you see fuzzy mold, discard the contents of the jar.
Kahm yeast vs. mold: A thin, flat, chalky white film across the brine surface is typically kahm yeast—a harmless, non-toxic wild yeast caused by oxygen exposure. While harmless, it can degrade flavor; skim it off with a spoon if it appears.
Smell and texture: Trust your senses. Properly fermented kohlrabi kimchi smells sour, pungent, and garlicky. If the jar ever smells of putrefaction, ammonia, or rotten sulfur, or if the vegetable cubes turn slimy rather than crisp, discard the batch immediately.

Frequently Asked Questions

Can I include the kohlrabi greens in this kimchi?

Yes. Young, tender kohlrabi greens are edible and ferment nicely. Wash them thoroughly, slice them into 1-inch (2.5 cm) ribbons, and salt them alongside the cubed stems. Discard any tough, yellowing, or overly fibrous outer leaves.

Can I make this kohlrabi kimchi recipe vegan?

Absolutely. Replace the 2 tablespoons (30 ml) of fish sauce with 1.5 tablespoons (22 ml) of tamari or regular soy sauce, paired with 1/2 teaspoon of mushroom powder or kelp granules. This yields the same umami profile without animal products.

Can I substitute crushed red pepper flakes for gochugaru?

It is not recommended. Western red pepper flakes consist of crushed seeds and pods that yield sharp, piercing heat without the subtle smokiness, sweetness, or vibrant red hue characteristic of gochugaru. You can readily find gochugaru in Asian grocery stores or online.

Why is my kimchi not bubbling after two days?

Fermentation speed depends primarily on ambient room temperature. In cooler rooms (below 65°F / 18°C), visible bubbling can take 3 to 4 days to appear. As long as your salting measurements were accurate and the jar sits in a temperate room, the bacteria will do their work. Taste a cube: if it has developed a mild tang, the fermentation is proceeding safely.