How to Grow Curly Kale Winterbor

Curly Kale Winterbor

Brassica oleracea var. acephala

vegetable

Winterbor is a cold-hardy curly kale variety known for its deeply frilled, dark green leaves and exceptional frost tolerance. The dense, attractive foliage becomes sweeter after exposure to freezing temperatures, making it ideal for winter harvests. This heirloom cultivar can produce leaves for months and improves in flavor as temperatures drop.

Growing Conditions

☀️

Sun: Full sun, 6+ hours daily (tolerates partial shade)

💧

Water: Keep soil consistently moist but not waterlogged; provide 1-1.5 inches per week. Deep watering encourages stronger root systems and cold hardiness.

📏

Spacing: 12-18 inches

📅

Days to maturity: 50-65 days from transplant for first harvests; continues producing for 3-4 months

🌱

Planting depth: Plant seeds 0.25-0.5 inches deep; transplants at same depth as they were growing

Soil

Type: Well-draining, fertile loamy soil with high organic matter

pH: 6.0-7.5

Amendments:

Compost aged manure bone meal kelp meal

Growing Zones

Find your zone →

Zones 2-9; exceptional hardiness makes it perfect for cold climates and fall/winter gardening

2a 2b 3a 3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b 9a

Growth Stages

Seedling

7-10 days

Cotyledons emerge and first true leaves develop; seedlings are delicate with soft green foliage

Keep soil warm (65-75°F) and moist. Provide bright light to prevent leggy growth. Thin seedlings to prevent overcrowding.

Vegetative Growth

3-4 weeks

Strong development of rosette structure with increasingly frilly leaves; plant becomes stockier and bushier

Maintain consistent moisture and feed every 2-3 weeks with balanced fertilizer or fish emulsion. Mulch to retain moisture and regulate soil temperature. Watch for early pest pressure.

Mature Rosette

2-3 weeks before first full harvest

Full rosette form achieved with abundant, densely curled dark green leaves; plant reaches 12-18 inches tall

Begin selective harvesting from the bottom. Continue regular watering and fertilizing. This stage extends throughout the growing season.

Frost Hardening & Sweetening

Ongoing through fall/winter

Leaves develop enhanced curling and darkening; starches convert to sugars after frost exposure, improving flavor

Do not over-fertilize with nitrogen; this reduces cold hardiness. Allow light frosts to sweeten leaves. Reduce watering slightly if temperatures drop.

Continuous Harvest

3-4 months (fall through winter)

Plant maintains leaf production over extended period; new leaves emerge from center while outer leaves are harvested

Harvest outer leaves regularly to promote continued growth from the crown. In mild winters, Winterbor can produce through late December or January.

Companion Planting

Plan your garden →

Plant with:

Beets Onions Garlic Potatoes Chamomile Dill Marigolds Nasturtiums Celery Spinach

Avoid planting near:

Fennel Tomatoes Strawberries Pole beans other Brassicas (in close proximity)

Common Pests

Hand-pick caterpillars; use fine netting to exclude butterflies; apply Bacillus thuringiensis (Bt) spray; companion plant with cabbage moths' natural predators
Use floating row covers early; apply neem oil or insecticidal soap; dust with food-grade diatomaceous earth; row covers are most effective for young plants
Spray with strong water stream; use insecticidal soap or neem oil; encourage beneficial insects like ladybugs and parasitic wasps; avoid excess nitrogen
Hand-pick adults and egg clusters (remove leaves with eggs); use floating row covers; plant trap crops like mustard greens nearby
Yellow sticky traps; insecticidal soap; neem oil; encourage beneficial insects; increase air circulation

Uses

🍳

Salads & Fresh Eating

Culinary

Young, tender leaves are mild and slightly sweet, perfect for raw salads. The frilly texture adds visual appeal and pleasant mouthfeel. [source]

🍳

Cooking & Soups

Culinary

Mature leaves are excellent sautéed, braised, or added to soups, stews, and grain dishes. Cooking mellows any bitterness and creates tender, flavorful greens. [source]

🍳

Juices & Smoothies

Culinary

Nutrient-dense leaves are popular in green smoothies and fresh juices, often blended with fruits to mask bitterness. [source]

💊

Nutritional Superfood

Medicinal

Winterbor kale is packed with vitamins K, C, and A, plus lutein, zeaxanthin, and glucosinolates with potential anti-inflammatory and anti-cancer properties. [source]

🏠

Ornamental Garnish

Household

The deeply frilly, dark green leaves are visually striking and traditionally used as decorative edible garnish for serving platters and dishes. [source]

This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.

Harvest Tips

Begin harvesting outer leaves once plant is 8-10 inches tall (typically 50-65 days). Harvest leaves from bottom up, working your way around the plant. Pinch off leaves at the stem base rather than cutting to avoid damaging the crown. Morning harvest after frost yields the sweetest leaves. Winterbor continues producing through winter in cold climates; can often harvest until hard freeze (-10°F or below). Flavor improves dramatically after frost exposure. Tender inner leaves can be harvested throughout the season; outer leaves toughen as plant matures but remain edible.

Fun Facts

🌱 Winterbor's flavor actually improves after frost; freezing temperatures convert starches into sugars, making it naturally sweeter in winter months—this is why it was specifically bred for fall and winter harvest.
🌱 Kale is one of the oldest brassicas in cultivation, with origins tracing back to the Mediterranean region over 2,000 years ago, though modern curly varieties like Winterbor developed in the 20th century.
🌱 A single Winterbor plant can produce harvestable leaves for 3-4 months straight in optimal conditions, making it one of the most productive and sustainable leafy greens for home gardeners.

Want personalized planting timelines?

Get started free