How To Grow Kohlrabi In Canada | Complete Guide

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

Kohlrabi is one of the most interesting and underrated vegetables to grow in a Canadian garden. With its rounded, bulb-like stem, crisp white flesh, and mild flavour reminiscent of cabbage and broccoli, it is a versatile addition to both the vegetable patch and the kitchen.

This cool-season member of the cabbage family grows particularly well during Canada's mild spring and autumn weather. Many standard varieties mature in approximately 45–65 days, making kohlrabi an excellent choice for succession planting, raised beds, and smaller gardens.

Whether you start seeds indoors or sow directly into the garden, the key to growing tender kohlrabi is maintaining steady growth, providing adequate spacing, and harvesting before the swollen stems become tough or woody.

Kohlrabi Growing Guide at a Glance

Feature	Growing Requirement
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 in hot weather
Soil	Fertile, well-drained soil; pH 6.0–7.5
Start Indoors	Approximately 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	Approximately 5–10 days at 18–24°C (64–75°F)
Plant Spacing	10–15 cm (4–6 inches) for standard varieties
Row Spacing	30–45 cm (12–18 inches)
Water Needs	Consistent moisture; approximately 2.5 cm (1 inch) weekly as a starting point
Difficulty	Easy to moderate
Container Growing	Yes; pots at least 20–25 cm (8–10 inches) deep

Choosing Kohlrabi Varieties for Canadian Gardens

Kohlrabi varieties are generally divided into green and purple types. Both have pale flesh and a mild, slightly sweet flavour. The colour of the outer skin has little effect on how the vegetable is prepared or eaten.

Early Vienna Kohlrabi is a particularly useful choice for Canadian gardens. This early-maturing variety develops smooth, pale green swollen stems with crisp white flesh. Its relatively short growing season makes it suitable for both spring and autumn crops.

For the best flavour and texture, harvest Early Vienna when the swollen stems measure approximately 5–7.5 cm (2–3 inches) in diameter.

Other kohlrabi types include purple Vienna varieties and larger storage varieties such as Superschmelz. These can be interesting alternatives, but their recommended harvest sizes and maturity periods differ. Always follow the growing instructions for the particular variety being planted.

Caribou Growing Note: Start with Early Vienna

For gardeners growing kohlrabi for the first time, Early Vienna is a practical choice. Its compact size and relatively quick maturity make it easy to fit into spring and autumn vegetable planting schedules.

When to Plant Kohlrabi in Canada

Kohlrabi is a cool-season vegetable that grows best during mild weather. In most Canadian regions, gardeners can grow a spring crop and, where the growing season allows, a second crop for autumn harvesting.

For spring planting, start seeds indoors approximately 4–6 weeks before transplanting or direct sow once the soil becomes workable. Young plants tolerate cool conditions, but prolonged severe cold may encourage premature flowering.

For an autumn crop, direct sow standard varieties approximately 8–10 weeks before the first expected fall frost. This allows time for the swollen stems to develop before temperatures become consistently cold.

Kohlrabi Planting Calendar for Canada

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

In warmer regions, autumn crops often develop better flavour and texture than crops maturing during the hottest part of summer. Cooler weather encourages steady growth and helps maintain tenderness.

How to Start Kohlrabi Seeds Indoors

Starting kohlrabi indoors can provide an earlier harvest, especially in Canadian regions with a late spring. Use clean seed trays or small pots filled with a well-draining seed-starting mix.

1. Sow seeds: Plant approximately 0.5–1 cm (¼–½ inch) deep.
2. Provide suitable temperatures: Maintain approximately 18–24°C (64–75°F) for germination.
3. Keep the growing medium moist: Water gently without saturating the soil.
4. Provide strong light: Once seedlings emerge, use suitable grow lights for approximately 14–16 hours daily or provide an adequately bright growing location.
5. Thin seedlings: Keep one strong seedling per cell or pot.
6. Transplant while young: Move seedlings outdoors when they have approximately 3–4 true leaves, before they become rootbound.

Kohlrabi seeds usually germinate within 5–10 days under favourable conditions. Cooler temperatures may slow emergence.

Hardening Off and Transplanting Kohlrabi

Before moving indoor-grown seedlings into the garden, gradually harden them off over approximately 7–10 days. Begin with short periods in a sheltered outdoor location and increase their exposure to sunlight, wind, and cool temperatures.

Choose a garden bed with fertile, well-drained soil and at least 6 hours of sunlight daily.

• Spacing: Set Early Vienna plants approximately 10–15 cm (4–6 inches) apart, with 30–45 cm (12–18 inches) between rows.
• Planting depth: Transplant at approximately the same depth as the seedlings were growing in their pots.
• Root protection: Handle root balls carefully to minimize transplant shock.
• Watering: Water thoroughly immediately after transplanting.
• Pest protection: Use fine insect netting where cabbage root flies, flea beetles, or cabbage butterflies are common.

Avoid transplanting during the hottest part of the day. If warm weather is unavoidable, transplant in the evening or on a cloudy day and maintain steady soil moisture while plants establish.

Caribou Growing Note: Don't Bury the Swollen Stem

Unlike turnips or rutabagas, kohlrabi does not develop its edible portion underground. The rounded portion is a swollen stem that forms above the soil. Transplant at the original growing depth and avoid covering the developing stem with soil or mulch.

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

Kohlrabi Germination and Seedling Problems

Healthy kohlrabi seedlings should emerge relatively quickly and develop compact, sturdy growth. Most early problems are related to temperature, moisture, or lighting.

• Seeds fail to germinate: Check for dry or waterlogged growing medium, unsuitable temperatures, excessive sowing depth, or poor seed viability.
• Leggy seedlings: Usually indicate insufficient light, excessive warmth, or overcrowding.
• Seedlings collapse: May indicate damping-off disease. Use clean containers, well-draining growing medium, and adequate airflow.
• Slow growth: May result from cold temperatures, restricted roots, insufficient light, or inconsistent moisture.

Do not automatically add fertilizer when seedlings grow slowly. First check whether the growing conditions are suitable.

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

How to Direct Sow Kohlrabi Outdoors

Direct sowing is one of the easiest ways to grow kohlrabi, particularly for autumn crops. It eliminates transplant shock and allows plants to establish naturally in the garden.

1. Choose a sunny garden bed with fertile, well-drained soil.
2. Remove weeds and loosen the top layer of soil.
3. Sow seeds approximately 0.5–1 cm (¼–½ inch) deep, initially spacing them about 5 cm (2 inches) apart.
4. Water gently and keep the soil evenly moist until seedlings emerge.
5. Once seedlings develop their first true leaves, thin standard varieties to approximately 10–15 cm (4–6 inches) apart.

For a continuous supply, sow small batches every 2–3 weeks while temperatures remain suitable. Avoid scheduling crops to mature during prolonged summer heat.

Caribou Growing Note: Succession Planting

Rather than sowing an entire packet at once, plant a short row every two or three weeks during cool weather. This produces several smaller harvests of tender kohlrabi instead of one large crop that may become overmature.

Soil, Watering, and Fertilizing Kohlrabi

Soil Preparation

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

Avoid planting kohlrabi repeatedly in soil where other cabbage-family crops have recently grown, particularly if clubroot or other soilborne diseases have occurred.

Watering

Consistent moisture is essential for producing crisp, tender swollen stems. As a starting point, provide approximately 2.5 cm (1 inch) of water weekly, including rainfall. Adjust for soil type, rainfall, and temperature.

Water deeply at the root zone rather than allowing the soil to repeatedly dry out and then become saturated. Irregular moisture can contribute to tough or cracked stems.

Apply a light layer of organic mulch to conserve moisture and suppress weeds, keeping mulch away from the developing swollen stems.

Fertilizing

In healthy garden soil amended with compost, additional fertilizer may not be necessary. If soil fertility is low, use a balanced vegetable fertilizer according to soil test recommendations or product directions.

Avoid excessive nitrogen, which may encourage lush foliage without improving the quality of the swollen stems.

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

Growing Kohlrabi in Raised Beds and Containers

Kohlrabi is well suited to raised beds, container gardens, and other small growing spaces because standard varieties remain relatively compact.

• Raised beds: Use fertile, well-drained soil and maintain the recommended plant spacing.
• Containers: Choose pots at least 20–25 cm (8–10 inches) deep, with adequate drainage and sufficient 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 than plants growing in the ground, particularly during warm or windy weather.

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

Common Kohlrabi Pests and Diseases

As a member of the brassica family, kohlrabi can attract many of the same pests that affect cabbage, broccoli, kale, and cauliflower. Inspect plants regularly, particularly while they are young.

Fine insect netting installed early is particularly useful for preventing damage from several common cabbage-family pests. Secure the edges so insects cannot enter underneath.

Common Kohlrabi Growing Problems

Why Is My Kohlrabi Not Forming a Swollen Stem?

The plant may still be immature, or growth may be affected by overcrowding, insufficient sunlight, drought, poor fertility, or prolonged heat. Provide adequate spacing and consistent moisture, and allow enough time for the stem to develop.

Why Is My Kohlrabi Woody or Tough?

Woody stems are often associated with overmaturity, hot weather, or interrupted growth. Harvest Early Vienna at approximately 5–7.5 cm (2–3 inches) in diameter for the best texture.

Why Is My Kohlrabi Bolting?

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

Why Are My Kohlrabi Stems Cracking?

Sudden changes in soil moisture, particularly heavy watering after drought, can cause swollen stems to split. Maintain steady moisture throughout the growing season.

Why Are My Kohlrabi Leaves Yellow?

Yellowing may result from overwatering, nutrient deficiencies, pest damage, disease, or normal aging of older leaves. Inspect the entire plant and check soil moisture before deciding on treatment.

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

When and How to Harvest Kohlrabi

Most standard kohlrabi varieties are ready to harvest approximately 45–65 days after sowing, depending on the variety and growing conditions.

For Early Vienna Kohlrabi, harvest when the swollen stem reaches approximately 5–7.5 cm (2–3 inches) in diameter. At this stage, the flesh is usually crisp, tender, and mildly sweet.

1. Check the swollen stem for size and firmness.
2. Use a sharp knife to cut the stem just below the swollen portion, or lift the entire plant.
3. Trim away roots and leaves before storing.
4. Refrigerate promptly to preserve freshness.

Young kohlrabi leaves are also edible and can be cooked similarly to kale or collard greens. Established plants tolerate light frost, making autumn harvesting especially practical in many Canadian regions.

Caribou Growing Note: Harvest for Tenderness

Don't wait for Early Vienna stems to become exceptionally large. Smaller, properly matured stems generally offer the best eating quality. Check plants frequently as they approach harvest size.

Read More | When to Harvest Vegetables | Beginner Timing Guide

How to Store and 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. Under favourable conditions, standard kohlrabi varieties may remain fresh for approximately one to two weeks or longer.

For longer storage, peel and cut the stems, blanch briefly, cool in ice water, drain thoroughly, and freeze in suitable containers. Frozen kohlrabi is best used in cooked dishes.

Kohlrabi can be enjoyed raw in salads, slaws, and vegetable platters, or cooked by roasting, steaming, sautéing, or adding 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

Frequently Asked Questions About Growing Kohlrabi

Is kohlrabi easy to grow in Canada?

Yes. Kohlrabi is well suited to Canada's cooler spring and autumn growing seasons. It is relatively quick to mature and grows well in garden beds and containers.

When should I plant kohlrabi in Ontario?

Spring planting generally takes place during April and May. For an autumn harvest, many Southern Ontario gardeners sow again during July or early August, depending on the variety and expected first frost.

Can I grow kohlrabi during summer?

Yes, particularly in cooler Canadian regions. In warmer areas, prolonged heat may reduce stem quality, making spring and autumn preferable.

Is kohlrabi a root vegetable?

No. The rounded edible portion is a swollen stem that develops above the soil, not a root.

How long does kohlrabi take to grow?

Many standard varieties mature approximately 45–65 days after sowing, depending on the variety and growing conditions.

How big should Early Vienna Kohlrabi be when harvested?

Approximately 5–7.5 cm (2–3 inches) in diameter for the best tenderness and flavour.

Can kohlrabi survive frost?

Established plants tolerate light frost, although prolonged severe freezing can damage the swollen stems.

Why is my kohlrabi tough or woody?

Common causes include harvesting too late, hot weather, and inconsistent moisture. Harvest at the recommended size and encourage steady growth.

Can I grow kohlrabi in a container?

Yes. Use a container at least 20–25 cm (8–10 inches) deep, with good drainage and sufficient room for each plant.

Can you eat kohlrabi raw?

Yes. Its crisp, mildly sweet flesh is excellent in salads, slaws, and as fresh vegetable sticks.

Do you need to peel kohlrabi?

Small, tender stems may have relatively thin skin. Larger or more mature stems generally benefit from peeling to remove the tougher outer layer.

Can I grow kohlrabi in the same bed every year?

It is better to rotate kohlrabi with unrelated crops rather than repeatedly planting cabbage-family vegetables in the same soil. Rotation helps reduce certain pest and disease problems.

Grow Kohlrabi from Seed Today

Kohlrabi is a productive and versatile vegetable that deserves a place in more Canadian gardens. Its relatively quick maturity, compact growing habit, and preference for cool weather make it an excellent choice for spring and autumn planting.

For reliable results, start with Early Vienna Kohlrabi, provide fertile soil and consistent moisture, and harvest while the swollen stems are still young and tender.

Featured Kohlrabi Seeds

Early Vienna Kohlrabi Seeds Grow an early-maturing kohlrabi variety with pale green swollen stems, crisp white flesh, and a mild, nutty flavour. Excellent for spring and autumn harvests in Canadian vegetable gardens.

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

See You in the Garden!