Growing Kohlrabi: A Complete Beginner's Guide

Growing Kohlrabi: A Complete Beginner's Guide

Welcome to the world of growing kohlrabi (Brassica oleracea var. gongylodes)! Also called "German turnip," this unique vegetable looks like an alien spaceship but tastes like a mild, sweet cross between cabbage and turnip. With its quick growth, high nutrition, and easy care, kohlrabi is an excellent choice for beginning gardeners.

Why Grow Kohlrabi?

Unique Appearance and Flavor

Kohlrabi grows a swollen, bulb-like stem above ground that's unlike any other vegetable. The flavor is mild, sweet, and crisp—delicious raw in salads or cooked in stir-fries and soups.

Fast Growing

One of the quickest vegetables to mature, kohlrabi is ready to harvest in just 55-60 days. This makes it perfect for impatient gardeners or filling gaps in your garden.

Nutritional Powerhouse

Kohlrabi is exceptionally high in vitamin C:

• 100g provides 62mg vitamin C (69% daily value)
• Good source of potassium and fiber
• Contains glucosinolates (cancer-fighting compounds)
• Rich in antioxidants and carotenoids
• Only 27 calories per 100g

Versatile in the Kitchen

• Eat raw: Sliced for snacking, julienned in salads, or made into slaw
• Cooked: Roasted, stir-fried, added to soups, mashed like potatoes
• Leaves: Edible and nutritious, cook like collards or kale

Easy to Grow

As a member of the cabbage family, kohlrabi shares their cold tolerance and relatively simple growing requirements. It's more pest-resistant than many brassicas and stands well in the garden after maturity.

Understanding Kohlrabi

Plant Anatomy

The edible "bulb" is actually a swollen stem, not a root:

• Bulb (stem): Grows above ground, 2-4 inches diameter at harvest
• Leaves: Large, gray-green, grow directly from the bulb on long stems
• Skin: Green, white, or purple depending on variety
• Flesh: Crisp, white to pale green, juicy

Types of Kohlrabi

Climate Requirements

Choosing Your Varieties

Best Varieties for Beginners

Giant Varieties (Harvest Later)

Pro Tip: Start with 'Early White Vienna' or 'Grand Duke' for your first crop. They're reliable and quick.

What You'll Need

Essential Supplies

• Seeds or transplants
• Well-draining soil
• Compost or aged manure
• Balanced fertilizer
• Mulch
• Row covers (optional, for pest protection)

Space Requirements

Kohlrabi is compact and space-efficient:

• Spacing: 4-6 inches apart for standard varieties
• Row spacing: 12-18 inches
• Giant varieties: 10-12 inches apart
• Container size: 6-inch pot per plant

Step-by-Step Growing Guide

Step 1: When to Plant

Spring Planting:

• Start seeds indoors 4-6 weeks before last frost
• Transplant outdoors 2-4 weeks before last frost
• Direct sow as soon as soil can be worked

Fall Planting (Often Best):

• Direct sow 8-10 weeks before first fall frost
• Fall crops are sweeter due to cooler temperatures
• Less pest pressure than spring

Step 2: Starting Seeds Indoors

1. Fill seed trays with moist seed-starting mix
2. Sow seeds 1/4 - 1/2 inch deep
3. Keep soil moist and at 65-75°F (18-24°C)
4. Expect germination in 5-10 days
5. Provide bright light (12-14 hours)
6. Thin to one seedling per cell

Step 3: Direct Sowing Outdoors

1. Prepare soil by adding 2-3 inches of compost
2. Create shallow furrows 1/4-1/2 inch deep
3. Sow seeds 1 inch apart
4. Cover lightly and water gently
5. Thin seedlings to 4-6 inches apart when 2-3 inches tall

Step 4: Transplanting

1. Harden off seedlings for 5-7 days
2. Transplant when seedlings have 3-4 true leaves
3. Space 4-6 inches apart
4. Plant at the same depth as in containers
5. Water deeply after planting
6. Add 2 inches of mulch

Care and Maintenance

Watering

Consistent moisture produces tender, crisp bulbs:

• 1-1.5 inches of water per week
• Keep soil evenly moist
• Mulch to retain moisture
• Inconsistent watering causes cracking and tough texture

Fertilizing

Mulching

• Apply 2 inches of organic mulch
• Keep mulch away from the developing bulb
• Helps maintain cool, moist soil
• Reduces weeds

Common Problems and Solutions

Pests

Diseases

Environmental Issues

Problem: Woody, tough bulbs

• Cause: Harvested too late, heat stress, inconsistent watering
• Solution: Harvest at 2-3 inches, keep cool, water consistently

Problem: Cracking

• Cause: Irregular watering or rapid growth after drought
• Solution: Maintain consistent moisture

Problem: Bolting (flowering)

• Cause: Prolonged cold exposure, then warmth
• Solution: Plant at right time, use bolt-resistant varieties

Problem: Small bulbs

• Cause: Overcrowding, poor soil, insufficient water
• Solution: Thin properly, amend soil, water regularly

Harvesting Kohlrabi

When to Harvest

• Standard varieties: When bulbs are 2-3 inches in diameter
• Giant varieties: Can grow to 8-10 inches while staying tender
• Leaves can be harvested anytime
• Don't wait too long—older bulbs become woody

How to Harvest

1. Grasp the bulb near the base
2. Pull straight up or cut at soil level
3. Cut off leaves (save for cooking)
4. Trim root end
5. Peel skin before eating if desired

Storage

• Refrigerator: 2-4 weeks (remove leaves first)
• Root cellar: 2-3 months at 32-40°F
• Can be frozen (blanch first)

Quick Reference Guide

Troubleshooting Guide

Problem: Seeds not germinating

• Cause: Soil too warm (>80°F), too cold (<40°F), or too dry
• Solution: Optimal temp 65-75°F, keep moist

Problem: Leggy seedlings

• Cause: Insufficient light
• Solution: Provide 12-14 hours bright light

Problem: Plants wilting in afternoon

• Cause: Insufficient water or root damage
• Solution: Check moisture, look for root maggots

Problem: Purple varieties turning green

• Cause: Normal—only skin is purple, flesh is white
• Solution: No action needed, this is normal

Next Steps

Once you've mastered basic kohlrabi growing:

1. Try different varieties (purple, giant)
2. Experiment with fall planting for sweeter bulbs
3. Use succession planting for extended harvest
4. Explore different cooking methods

Kohlrabi is an underappreciated gem in the vegetable garden. Once you taste your first home-grown bulb, you'll wonder why you didn't grow it sooner!