How to Grow Kale in Canada: Complete Guide

Why Grow Kale in Canada?

If there is one leafy green that was made for the Canadian climate, it is kale. This cold-hardy brassica laughs at frost, actually tastes better after a freeze, and can produce harvestable leaves from May through December in many parts of the country. While other crops succumb to the first fall frost, kale stands tall and keeps producing, making it one of the most valuable crops in a Canadian garden.

Kale is nutritionally dense -- packed with vitamins A, C, and K, along with calcium and iron. It is versatile in the kitchen, working equally well in salads, smoothies, soups, chips, and stir-fries. It is also remarkably easy to grow, tolerating a wider range of conditions than most vegetables. For Canadian gardeners looking for a productive, low-maintenance crop that spans the entire growing season, kale is hard to beat.

When to Plant Kale

Kale is a cool-season crop that can be planted in both spring and late summer. It tolerates frost down to -7 C (20 F), and established plants can survive even colder temperatures with some protection.

Spring planting:

• British Columbia (coastal): Transplant outdoors mid-March to early April
• Southern Ontario (Zones 5-6): Transplant mid to late April
• Prairies (Zones 3-4): Transplant mid to late May
• Quebec and Maritimes (Zones 4-5): Transplant late April to mid-May

Fall planting: For a fall and winter harvest, transplant seedlings 10 to 12 weeks before your average first fall frost date. This is typically mid-July to early August for most of Canada.

Check your frost dates for precise timing in your area.

Starting Seeds vs Direct Sowing

Both methods work, but transplanting is preferred for several reasons.

Indoor seed starting gives kale a head start and produces more uniform plants. Start seeds indoors 4 to 6 weeks before your planned transplant date. Use 72-cell or 50-cell flats. Kale seeds germinate quickly -- 5 to 7 days at 18 to 24 C (65 to 75 F). Transplant seedlings outdoors when they have 3 to 4 true leaves and have been hardened off for a week.

Direct sowing works well for fall plantings when soil is warm and germination is fast. Sow seeds 1 cm (1/2 inch) deep. Thin seedlings to their final spacing once they are 8 to 10 cm (3 to 4 inches) tall.

For spring plantings in Zones 3 and 4, starting indoors is strongly recommended. The short season means every week of head start counts.

Spacing in 30-Inch Beds

Kale is a moderately large plant that needs room for good airflow and leaf development. In a 30-inch biointensive bed, three rows work well.

With 3 rows and 12-inch in-row spacing, you get about 3 plants per bed foot. A 12-foot bed holds roughly 36 kale plants. That is a generous supply -- each plant produces heavily over a long season. For a family of four, 8 to 12 plants is usually more than enough for fresh eating, with surplus for freezing.

Growing Tips

Soil. Kale prefers fertile, well-drained soil with a pH of 6.0 to 7.5. Like all brassicas, it is a moderately heavy feeder. Amend beds with compost before planting and side-dress with a nitrogen-rich organic fertilizer (such as blood meal or feather meal) once plants are established and actively growing.

Watering. Provide consistent moisture -- about 2.5 cm (1 inch) per week. Kale is more drought-tolerant than lettuce or spinach, but consistent watering produces the best-tasting, most tender leaves. Stressed kale becomes tough and bitter.

Mulching. Mulch around plants with straw or shredded leaves to retain moisture, suppress weeds, and keep roots cool in summer heat.

Winter harvesting. In Zones 5 and warmer, kale can survive the entire winter with minimal protection. In Zones 3 and 4, mulch heavily around the base and use a row cover or cold frame to extend the harvest into December or even January. Frozen kale leaves thaw and droop but are still excellent for cooking.

Recommended varieties for Canadian gardens:

• Curly: Winterbor (extremely cold-hardy), Dwarf Blue Curled Scotch, Redbor (burgundy colour)
• Lacinato (Tuscan/Dinosaur): Black Magic, Toscano, Nero di Toscana
• Russian/Siberian: Red Russian (tender, great for salads), White Russian
• Specialty: Dazzling Blue (beautiful blue-green with purple stems)

Available from West Coast Seeds, William Dam Seeds, OSC Seeds, and Vesey's.

Harvesting

Begin harvesting outer leaves when they are 20 to 25 cm (8 to 10 inches) long, leaving the central growing point and inner leaves intact. This "cut and come again" method allows each plant to produce continuously for months.

Always harvest from the bottom up, taking the oldest, largest leaves first. A healthy kale plant looks like a little palm tree by late summer, with a bare stalk below and a crown of leaves on top.

Avoid stripping more than a third of the leaves at once. The plant needs foliage for photosynthesis and continued growth.

Post-frost harvest: Kale harvested after a hard frost is noticeably sweeter. The cold triggers the plant to convert starches to sugars as a natural antifreeze, producing the sweet, mellow flavour that makes fall kale superior to summer kale.

Storage: Fresh kale keeps in the refrigerator for about a week. For long-term storage, wash, strip leaves from stems, blanch for 2 to 3 minutes, and freeze flat on a baking sheet before transferring to freezer bags. Frozen kale works well in soups, smoothies, and sauteed dishes.

Common Problems

Cabbage worms and cabbage loopers. Green caterpillars that chew ragged holes in leaves. Cover plants with lightweight insect netting to prevent the white butterflies from laying eggs. Handpick caterpillars and check the undersides of leaves for yellow egg clusters. Bacillus thuringiensis (Bt) spray is an effective organic control.

Aphids. Grey-green cabbage aphids can build up quickly on kale, especially in warm, dry weather. A strong spray of water dislodges most of them. Insecticidal soap is effective for heavy infestations. Encourage beneficial insects like ladybugs and parasitic wasps by planting flowers near your vegetable beds.

Flea beetles. Tiny black beetles that create small round holes in leaves, making them look like they have been hit with a shotgun. Most common on young transplants in spring. Row cover prevents damage. Established plants typically outgrow flea beetle pressure.

Plan Your Kale Garden

Our free garden calculator will calculate planting dates for kale based on your province and frost dates, for both spring and fall plantings. For a full overview of bed preparation, transplanting techniques, and season planning, visit our getting started guide.