How to Grow Kohlrabi: Complete Guide

If you’ve never grown kohlrabi before, you’re in for a good time. This is one of the most forgiving, fastest, and frankly most entertaining vegetables you can put in the ground. It goes from seed to table in about 55 to 60 days. It tolerates light frost. It doesn’t need much space. And watching that little bulb swell up above the soil line is weirdly satisfying.

Whether you’re a first-time gardener or just looking to add something new to the rotation, kohlrabi is an outstanding choice. Here’s everything you need to know to grow it well.

Why Kohlrabi Is Great for Beginners

Let’s start with the case for kohlrabi as a starter vegetable:

• It’s fast. Most varieties mature in 55 to 60 days. That’s about half the time of a tomato and faster than most root vegetables.
• It’s cool-season. You plant it when not much else is going in the garden — early spring and fall. It fills gaps in the growing calendar.
• It handles frost. Light frosts (down to about 28°F) won’t kill it. A touch of cold can even sweeten the flavor.
• Pest pressure is manageable. It attracts the usual brassica pests but nothing extraordinary, and its short growing window means problems rarely have time to get serious.
• It’s not fussy. Reasonable soil, regular water, some sunlight — that’s about it.

If you can grow radishes, you can grow kohlrabi. It’s barely more complicated.

When to Plant Kohlrabi

Kohlrabi is a cool-season crop. It grows best when daytime temperatures are between 60°F and 75°F. Heat is the enemy — anything consistently above 80°F and the bulb gets woody, fibrous, and unpleasant. It may bolt (send up a flower stalk) and stop putting energy into the part you actually eat.

This gives you two planting windows in most climates:

Spring Planting

Start seeds indoors 4 to 6 weeks before your last expected frost date. Transplant seedlings outside about 2 weeks before the last frost — kohlrabi handles light freezes just fine.

Alternatively, direct sow seeds outdoors as soon as the soil can be worked in spring, typically 3 to 4 weeks before the last frost date.

The goal is to get the bulb formed before summer heat arrives. In most of the US (zones 5 through 7), that means planting seeds in March or early April for a May to June harvest.

Fall Planting

This is actually the better window in many regions. The quality tends to be higher because the bulbs mature as temperatures cool down rather than heat up.

Count backward 60 to 70 days from your first expected fall frost. That’s your planting date. In zone 6, for example, you’d sow in late July or early August for an October harvest.

Fall-planted kohlrabi often tastes sweeter than spring-planted, because cool nights encourage the plant to convert starches to sugars. The same thing happens with carrots and parsnips.

Mild Climates

If you’re in zones 8 through 10, you may be able to grow kohlrabi through winter. Sow in fall and harvest through the cooler months. Avoid planting in late spring or summer — the heat will work against you.

Choosing Varieties

There are dozens of kohlrabi cultivars, but a few stand out for home gardeners. For the full guide to kohlrabi varieties, see our dedicated article.

• Early White Vienna — The classic. Pale green skin, white flesh, matures in about 55 days. Reliable and widely available.
• Early Purple Vienna — Same deal, purple skin. Slightly more peppery. Same white flesh inside. Looks great in the garden.
• Kolibri — A popular hybrid purple variety. Vigorous, uniform, with good resistance to woodiness. Excellent flavor.
• Kossak — If you want giant kohlrabi (up to 8 to 10 inches across), this is the one. Remarkably, it stays tender even at larger sizes. Takes a bit longer, about 80 days.
• Superschmelz — Another giant variety from Germany. Can reach several pounds without going woody. A conversation piece at the farmers market.

For your first time, stick with Early White Vienna or Kolibri. They’re proven, fast, and hard to mess up.

Soil Preparation

Kohlrabi isn’t picky about soil, but it performs best in:

• Loose, well-drained soil — The bulb forms above ground, but good root development matters. Compacted soil slows things down.
• pH between 6.0 and 7.5 — Slightly acidic to neutral. Most garden soils are fine without amendment.
• Reasonable fertility — Work in a couple inches of compost before planting. Kohlrabi is a moderate feeder. It doesn’t need heavy fertilization, but poor soil produces small, slow bulbs.

If your soil is heavy clay, lighten it with compost or plant in raised beds. Sandy soil works fine but may need more frequent watering.

Avoid spots where you’ve recently grown other brassicas (broccoli, cabbage, kale, cauliflower). Rotating crops helps prevent the buildup of soil-borne diseases like clubroot that affect the entire family.

Starting from Seed: Direct Sow vs. Transplant

You have two options, and both work well.

Direct Sowing

The simpler method. Sow seeds directly into the garden:

1. Plant seeds 1/4 to 1/2 inch deep.
2. Space seeds about 1 inch apart in rows 12 inches apart.
3. Keep soil consistently moist until germination (5 to 10 days, depending on soil temperature).
4. Once seedlings have 2 to 3 true leaves, thin to 4 to 6 inches apart. This spacing is important — crowded kohlrabi produces small, misshapen bulbs.

Direct sowing is best for fall planting when you’re sowing into warm soil and germination is fast.

Starting Indoors and Transplanting

Better for spring planting, when you want a head start:

1. Start seeds indoors in cell trays or small pots, 4 to 6 weeks before you plan to transplant.
2. Use a standard seed-starting mix. Keep moist and warm (65°F to 75°F) until germination.
3. Grow seedlings under lights or in a bright window. Keep them from getting leggy — if they stretch toward light, they need more of it.
4. Harden off for a week before transplanting. Move seedlings outside for a few hours a day, gradually increasing exposure to sun and wind.
5. Transplant into the garden at 4 to 6 inch spacing, in rows 12 inches apart.
6. Water well at transplanting. Kohlrabi transplants settle in quickly.

Don’t let transplants get too old before planting out. If they become rootbound or stressed in their pots, they’re more likely to bolt.

Spacing and Layout

• Between plants: 4 to 6 inches
• Between rows: 12 inches
• In raised beds or intensive planting: 6 inches in all directions (grid pattern)

Kohlrabi doesn’t need much room. A 4x4 raised bed can hold 36 to 64 plants, which is a serious amount of kohlrabi. Even a large container (at least 12 inches deep) can support 3 to 4 plants.

Watering

Consistent moisture is the single most important thing you can provide. Kohlrabi that goes through cycles of wet and dry develops a tough, woody texture — the number one quality complaint from home growers.

• Water deeply 1 to 2 times per week, depending on weather and soil type.
• Aim for about 1 inch of water per week total (including rain).
• Mulch around plants with straw, shredded leaves, or grass clippings. Mulch keeps soil moisture even and reduces temperature swings.
• Don’t overwater to the point of waterlogging. Well-drained soil matters.

If you’re growing in containers, check moisture daily. Containers dry out much faster than garden beds.

Fertilizing

Kohlrabi is a moderate feeder. If you worked compost into the soil at planting, you may not need additional fertilizer at all for a short-season crop.

If your soil is lean, or you want to push growth:

• Side-dress with a balanced granular fertilizer (10-10-10) or compost about 3 weeks after transplanting or thinning.
• A light application of fish emulsion or diluted liquid fertilizer every 2 to 3 weeks works well for organic gardeners.
• Don’t overdo nitrogen. Excess nitrogen promotes leaf growth at the expense of bulb formation. You want a bulb, not a kale plant.

Common Problems (and How to Avoid Them)

Bolting

Bolting means the plant sends up a flower stalk instead of forming a good bulb. It’s triggered by stress — usually temperature swings or extended heat.

Prevention: Plant at the right time so bulbs mature in cool weather. Don’t let plants get stressed from drought or root disturbance. Avoid transplanting seedlings that are already too mature.

Woody, Fibrous Bulbs

This is the most common disappointment. You wait patiently, harvest a nice-looking bulb, slice it open, and it’s tough and stringy.

Causes: Heat stress, inconsistent watering, harvesting too late, or poor variety choice.

Prevention: Harvest on time (see below), water consistently, and grow in the right season. Giant varieties like Kossak and Superschmelz are bred to resist woodiness at larger sizes. Standard varieties need to be picked younger.

Cabbage Worms and Aphids

As a brassica, kohlrabi attracts cabbage white butterflies (whose larvae — green caterpillars — eat the leaves) and aphids.

Management: Row covers are the best organic defense. A lightweight floating row cover keeps butterflies from laying eggs on your plants. For aphids, a strong spray of water from the hose knocks them off. Serious infestations can be treated with insecticidal soap or neem oil.

Neither pest will directly damage the bulb, but heavy leaf damage slows growth and can reduce bulb size.

Clubroot

A soil-borne disease that causes swollen, distorted roots and stunted growth. It affects all brassicas and can persist in soil for years.

Prevention: Rotate crops. Don’t plant brassicas in the same spot more than once every 3 to 4 years. Maintain soil pH above 7.0 if clubroot is a known problem in your area — the pathogen struggles in alkaline conditions.

Flea Beetles

Tiny beetles that chew small round holes in leaves. Damage is usually cosmetic on mature plants but can be serious on seedlings.

Management: Row covers again. Or just tolerate it — established kohlrabi plants can handle moderate flea beetle damage without any effect on the bulb.

Harvesting Kohlrabi

This is where most people go wrong. They wait too long.

Harvest standard varieties when the bulb is 2 to 3 inches in diameter. That’s roughly the size of a tennis ball. At this size, the flesh is tender, crisp, and sweet. Every day you wait past this point, the texture gets tougher and the flavor gets stronger.

To harvest:

1. Cut the stem at ground level with a sharp knife, or pull the whole plant.
2. Trim off the leaf stalks. (Save the leaves — kohlrabi leaves are edible and taste like a cross between kale and collard greens.)
3. The bulb stores well in the fridge for 2 to 3 weeks. See our guide on how to store kohlrabi for longer-term options. Even longer if you remove the leaves and store in a plastic bag in the crisper drawer.

Giant varieties (Kossak, Superschmelz) are the exception — these can be harvested at 6 to 10 inches and still be tender. But test by slicing a small piece first. If it’s fibrous, you’ve waited too long.

How to Tell If It’s Ready

• The bulb is clearly visible above the soil.
• It’s round and firm, not cracked or splitting.
• At 2 to 3 inches across for standard varieties.
• The skin is smooth, not rough or corky.
• When you press a fingernail into the flesh, it gives easily — a sign of tenderness.

Succession Planting: Keep the Harvest Going

Because kohlrabi matures quickly, you can plant several rounds for a continuous harvest:

• Sow a new batch every 2 to 3 weeks during your spring or fall planting window.
• Stagger varieties (early and late maturing) for an even longer harvest window.
• In a 12-week fall season, you could realistically get 4 to 5 successive sowings from a single bed.

This is one of kohlrabi’s best tricks for home gardeners. Instead of harvesting 30 bulbs all at once (which is fun but chaotic), you get a steady supply of 6 to 8 bulbs every couple weeks.

Growing Kohlrabi in Containers

For a complete guide, see our article on growing kohlrabi in containers. Kohlrabi adapts well to containers. Use:

• A pot at least 12 inches deep and 12 inches wide.
• A good-quality potting mix (not garden soil, which compacts in containers).
• Plant 3 to 4 plants per container of that size.
• Water more frequently — containers dry out fast, and inconsistent moisture leads to woody bulbs.
• Place in a spot that gets at least 6 hours of direct sunlight.

Container-grown kohlrabi is perfect for patios, balconies, or supplementing a small garden.

Quick Reference

Detail	Guideline
Days to harvest	55-60 (standard), 70-80 (giant)
Planting depth	1/4 to 1/2 inch
Spacing	4-6 inches apart, rows 12 inches apart
Sun	Full sun (6+ hours)
Water	1 inch per week, consistent
Soil pH	6.0-7.5
Harvest size	2-3 inches (standard)
Frost tolerance	Light frost, down to ~28°F

Start Growing

Kohlrabi might be the best-kept secret in the vegetable garden. It’s fast enough to squeeze into gaps in the schedule, easy enough for a first-time grower, and rewarding enough to earn a permanent place in the rotation.

If you enjoy growing brassicas, consider also trying growing Brussels sprouts — they take longer but reward you with a dramatic harvest in late fall.

Pick up a packet of seeds, find a spot with decent sun, and give it a try. In two months, you’ll have a harvest. In three months, you’ll be telling your friends about it.