How To Grow Kohlrabi In Canada | Complete Guide

Download | How to Grow Kohlrabi | Complete Growing Guide (PDF)

Kohlrabi is a distinctive, easy-to-grow vegetable with a crisp texture and mild, slightly sweet flavour reminiscent of cabbage and broccoli. Its rounded, bulb-like portion is actually a swollen stem that develops above the soil.

This cool-season member of the brassica family grows particularly well in Canadian gardens. Many varieties mature in approximately 45–65 days, making kohlrabi an excellent choice for spring and autumn harvests, raised beds, and smaller growing spaces.

Kohlrabi Growing Guide at a Glance

Feature	Growing Requirement / Detail
Botanical Name	Brassica oleracea Gongylodes Group
Plant Type	Cool-season biennial grown as an annual vegetable
Sun Exposure	Full sun; 6–8 hours daily. Light afternoon shade is beneficial during hot weather.
Soil	Fertile, well-drained soil; pH 6.0–7.5
Start Indoors	4–6 weeks before spring transplanting
Direct Sow	Early spring or midsummer for an autumn harvest
Sowing Depth	0.5–1 cm (¼–½ inch)
Germination	5–10 days at approximately 18–24°C (64–75°F)
Plant Spacing	10–15 cm (4–6 inches); 20–30 cm (8–12 inches) for large varieties
Row Spacing	30–45 cm (12–18 inches)
Water Needs	Moderate; maintain consistent moisture
Difficulty Level	Easy to moderate
Container Friendly	Yes; containers at least 20–25 cm (8–10 inches) deep

Best Kohlrabi Varieties for Canadian Gardens

Both green and purple kohlrabi grow well in Canada. Early varieties are ideal for quick spring harvests, while larger varieties are better suited to autumn harvesting and storage.

Caribou Growing Note: Choosing Your Variety

For quick harvests, choose Early White Vienna or Early Purple Vienna. For larger autumn crops, consider Superschmelz. Always follow the recommended harvest size for your variety to maintain the best texture.

When to Plant Kohlrabi in Canada

Kohlrabi grows best in cool weather. Plant in early spring for an early summer harvest or sow in midsummer for an autumn crop. Established plants tolerate light frost, but prolonged summer heat can make stems tough or woody.

For spring crops, start seeds indoors 4–6 weeks before transplanting or direct sow once the soil is workable. For autumn crops, sow standard varieties approximately 8–10 weeks before the first expected fall frost. Allow more time for large varieties.

Kohlrabi Planting Calendar for Canada

These dates are approximate. Adjust your schedule according to local frost dates, weather conditions, and the maturity period of your chosen variety.

How to Start Kohlrabi Seeds Indoors

Starting seeds indoors provides an earlier spring harvest, particularly in colder regions. Use seed trays or small pots filled with a moist, well-drained seed-starting mix.

1. Sow Seeds: Plant 0.5–1 cm (¼–½ inch) deep and cover lightly.
2. Provide Warmth: Maintain approximately 18–24°C (64–75°F) during germination.
3. Maintain Moisture: Keep the growing medium evenly moist but not saturated.
4. Provide Light: Once seedlings emerge, provide 14–16 hours of light daily under grow lights, positioning suitable lights approximately 5–10 cm (2–4 inches) above the seedlings and adjusting as they grow.
5. Thin Seedlings: Keep one healthy seedling per cell or pot.

Seedlings are generally ready for transplanting when they have approximately 3–4 true leaves. Avoid keeping them indoors too long, as rootbound seedlings may struggle after planting.

How to Transplant Kohlrabi Outdoors

Kohlrabi seedlings can be transplanted outdoors during cool spring weather once the soil is workable. For best results, transplant young, healthy seedlings with approximately 3–4 true leaves, before they become rootbound.

Gradually harden off indoor-grown seedlings for 7–10 days before planting to help them adjust to outdoor sunlight, wind, and temperatures.

Step-by-Step Transplanting Instructions

1. Prepare the Soil: Choose a sunny location with fertile, well-drained soil. Incorporate finished compost if needed.
2. Water Seedlings: Water the seedlings before transplanting to help keep their root balls intact.
3. Space Plants: Allow 10–15 cm (4–6 inches) between standard varieties and 20–30 cm (8–12 inches) for larger varieties. Space rows approximately 30–45 cm (12–18 inches) apart.
4. Handle Carefully: Remove seedlings from their containers without unnecessarily disturbing the roots.
5. Plant at the Correct Depth: Position seedlings at approximately the same depth they were growing in their containers. Do not bury the developing swollen stem.
6. Water Thoroughly: Water immediately after transplanting to settle the soil around the roots.
7. Protect Young Plants: Maintain consistent moisture and use fine insect netting if cabbage pests are active.

Can Kohlrabi Be Transplanted During Hot Weather?

Kohlrabi prefers cool growing conditions, and transplanting during hot weather can cause stress and slow growth. If warm-weather transplanting is necessary, choose a cloudy day or late afternoon, water thoroughly, and provide temporary shade until the seedlings become established.

Caribou Growing Note: Avoid Planting Too Deeply

Unlike root vegetables, kohlrabi develops its edible swollen stem above the soil. Transplant seedlings at their original growing depth and avoid covering the developing stem with soil or mulch.

Read More | Hardening Off Seedlings: 7-Day Canadian Plan

Kohlrabi Germination & Common Seedling Problems

Kohlrabi seeds generally germinate within 5–10 days at approximately 18–24°C (64–75°F). If seedlings fail to emerge, check the following conditions:

• Poor Germination: Dry soil, excessive moisture, unsuitable temperatures, old seeds, or sowing too deeply.
• Leggy Seedlings: Insufficient light, excessive warmth, or overcrowding.
• Seedlings Falling Over: Possible damping-off disease, often associated with excess moisture and poor airflow.

Use clean containers, fresh seed-starting mix, consistent moisture, and adequate light to encourage healthy growth.

Read More | Why Seeds Don't Germinate: 10 Common Causes

How to Direct Sow Kohlrabi Outdoors

Direct sowing is a simple, reliable way to grow kohlrabi, particularly for autumn crops.

1. Choose a sunny location with fertile, well-drained soil.
2. Loosen the soil and remove weeds.
3. Sow seeds 0.5–1 cm (¼–½ inch) deep, approximately 5 cm (2 inches) apart.
4. Water gently and maintain even moisture until germination.
5. Thin seedlings once their first true leaves develop, leaving 10–15 cm (4–6 inches) between standard varieties or 20–30 cm (8–12 inches) for large varieties.

For a longer harvest, sow small batches every 2–3 weeks during suitable cool weather. Pause during prolonged summer heat and resume for autumn planting.

Caribou Growing Note: Succession Planting

Rather than sowing an entire packet at once, plant a short row every two to three weeks during cool weather. This provides a steady supply of tender kohlrabi instead of one large harvest.

Soil, Watering & Fertilizing

Kohlrabi grows best in fertile, well-drained soil with a pH of approximately 6.0–7.5. Incorporate finished compost before planting to improve soil structure and moisture retention.

Watering

Consistent moisture is essential for tender, evenly developed stems. As a general starting point, provide approximately 2.5 cm (1 inch) of water weekly from rainfall and irrigation combined, adjusting for hot or dry conditions.

Water deeply and avoid allowing the soil to become excessively dry, especially while the stems are swelling. A thin layer of straw or shredded-leaf mulch can help conserve moisture and suppress weeds.

Fertilizing

In healthy soil amended with compost, additional fertilizer may not be necessary. If growth is slow or soil fertility is poor, apply a balanced vegetable fertilizer according to soil test results or product directions.

Avoid excessive nitrogen, which can encourage leafy growth without improving stem quality. If clubroot has been a problem in your garden, test the soil and follow local recommendations for managing soil pH and crop rotation.

Read More | How Often Should You Water a Vegetable Garden?

Growing Kohlrabi in Raised Beds & Containers

Kohlrabi is well suited to raised beds, containers, and small-space gardens. Its compact growth allows several plants to fit into a relatively small area.

• Raised Beds: Use fertile, well-drained soil and follow the recommended plant spacing.
• Containers: Choose pots at least 20–25 cm (8–10 inches) deep with adequate drainage. Allow enough width for each plant.
• Square Foot Gardens: Approximately four standard-sized plants can fit into one square foot when properly spaced.

Container-grown plants may need more frequent watering, particularly during warm weather.

Read More | Raised Bed vs In-Ground Garden | What Should You Choose?

Common Kohlrabi Pests, Diseases & Growing Problems

Like other brassicas, kohlrabi can be affected by cabbage pests and soilborne diseases. Inspect plants regularly and use fine insect netting early in the growing season to prevent insect damage.

Common Pests & Diseases

• Cabbage Worms: Caterpillars chew holes in leaves. Use insect netting and remove visible caterpillars.
• Flea Beetles: Cause numerous small holes in leaves, particularly on seedlings. Protect young plants with insect netting.
• Cabbage Root Maggots: Feed on roots, causing wilting and stunted growth. Crop rotation and insect exclusion help reduce risk.
• Aphids: Cluster on leaves and tender growth. Inspect regularly and manage infestations early.
• Slugs & Snails: Damage leaves during damp weather. Reduce hiding places and monitor plants.
• Clubroot: Causes swollen roots, yellowing, and wilting. Avoid moving contaminated soil and follow appropriate crop rotation and soil management practices.
• Black Rot & Downy Mildew: Can cause discoloured leaves and reduced plant health. Improve airflow, avoid prolonged leaf wetness, and remove diseased plant debris.

Why Is My Kohlrabi Not Forming a Swollen Stem?

Plants may be immature or stressed by overcrowding, insufficient sunlight, drought, poor fertility, or prolonged heat. Provide adequate spacing, consistent moisture, and suitable growing temperatures.

Why Is My Kohlrabi Woody or Tough?

Woody stems are commonly caused by overmaturity, hot weather, or interrupted growth. Harvest standard varieties at approximately 5–8 cm (2–3 inches) in diameter, maintain even moisture, and avoid prolonged heat stress.

Why Is My Kohlrabi Bolting?

Premature flowering can occur when young plants experience prolonged cold at a sensitive stage. Avoid exposing transplants to extended severe cold and harvest usable stems promptly if flower stalks begin developing.

Why Are My Kohlrabi Stems Cracking?

Sudden changes in soil moisture, particularly heavy watering after drought, may cause swollen stems to split. Maintain consistent moisture throughout growth.

Read More | The Balanced Garden: Natural Pest Control for Vegetables

When & How to Harvest Kohlrabi

Most standard kohlrabi varieties are ready approximately 45–65 days after sowing. Harvest when the swollen stems are firm and reach approximately 5–8 cm (2–3 inches) in diameter, unless the variety is bred for larger harvests.

To harvest, cut the stem just below the swollen portion with a sharp knife or lift the entire plant and trim away the roots. Remove the leaves before storage.

Established plants tolerate light frost, making kohlrabi particularly useful for autumn harvesting. However, harvest before prolonged severe freezing damages the stems.

Young kohlrabi leaves are also edible and can be steamed, sautéed, or prepared similarly to kale and collard greens.

Caribou Growing Note: Harvest for Tenderness

For most standard varieties, smaller stems offer the best flavour and texture. Check plants frequently as they approach maturity and harvest promptly. If you prefer larger kohlrabi, choose a variety specifically bred to remain tender at greater sizes.

Read More | When to Harvest Vegetables | Beginner Timing Guide

How to Store & Use Kohlrabi

Remove the leaves before storing kohlrabi to reduce moisture loss. Keep the swollen stems unwashed in a suitable produce bag or container in the refrigerator. Standard varieties generally store for approximately one to two weeks or longer under favourable conditions.

Large-storage varieties, such as Superschmelz, may keep considerably longer when stored close to 0°C (32°F) in high humidity without freezing.

For freezing, peel and cut the stems, blanch briefly in boiling water, cool in ice water, drain, and pack into freezer-safe containers. Frozen kohlrabi is best used in cooked dishes.

Kohlrabi can be enjoyed raw in salads and slaws, cut into sticks for dipping, roasted, steamed, sautéed, or added to soups and stews. Peel the outer skin if it is thick or fibrous.

Read More | How to Harvest, Store, and Use Your Garden Produce

Saving Kohlrabi Seeds

Kohlrabi is a biennial vegetable that generally produces seeds during its second growing season after exposure to suitable cold conditions.

To save seeds, select healthy plants from an open-pollinated variety and allow them to overwinter. In colder regions, plants may need to be lifted, stored under suitable conditions, and replanted the following spring.

Allow the plants to flower and form seed pods. Once the pods mature and begin drying, collect them, finish drying in a protected location, and store the cleaned seeds in a cool, dry place.

Kohlrabi can cross-pollinate with other compatible Brassica oleracea crops, including cabbage, broccoli, cauliflower, and kale. Appropriate isolation is necessary to maintain variety purity. Seeds saved from hybrids may not grow true to type.

Read More | How to Grow Cabbage in Canada | Complete Growing Guide

Frequently Asked Questions About Growing Kohlrabi

Can kohlrabi grow during summer?
Yes, particularly in cooler Canadian regions. In warmer areas, spring and autumn crops generally produce better results because prolonged heat can reduce stem quality.

Is kohlrabi a root vegetable?
No. Its edible, rounded portion is a swollen stem that grows above the soil.

Can kohlrabi survive frost?
Established plants tolerate light frost, but prolonged severe freezing can damage the swollen stems.

Do you need to peel kohlrabi?
Small, tender kohlrabi may have thin skin, while larger stems often need peeling to remove the tougher outer layer.

Can you eat kohlrabi raw?
Yes. Its crisp, mildly sweet flesh is excellent in salads, slaws, and vegetable platters.

Can I grow kohlrabi in the same garden bed every year?
It is better to rotate kohlrabi with unrelated crops rather than repeatedly planting brassicas in the same location. Rotation helps reduce the buildup of certain pests and soilborne diseases.

Grow Kohlrabi from Seed Today

Kohlrabi is a rewarding, compact vegetable for Canadian gardens. Its quick maturity and preference for cool weather make it especially useful for spring and autumn planting.

Choose a variety suited to your growing season, provide fertile soil and consistent moisture, and harvest stems at the recommended size for the best flavour and texture.

Featured Kohlrabi Seeds

Kohlrabi 'Early Vienna' An early-maturing variety producing pale green, swollen stems with crisp, white flesh and mild, nutty flavour. Best harvested at approximately 5–7.5 cm (2–3 inches) in diameter. Shop Kohlrabi Seeds

Download | How to Grow Kohlrabi | Complete Growing Guide (PDF)

See You in the Garden!