How to Grow Kale (Winterbor)
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Kale (Winterbor)
Brassica oleracea var. acephala
vegetableWinterbor kale is a cold-hardy, frost-tolerant leafy green with deeply frilly, blue-green leaves that become sweeter after freezing temperatures. This heirloom variety produces tender, tender leaves ideal for raw consumption, cooking, and juicing. It's particularly prized for fall and winter harvests when flavors intensify and nutrient density peaks.
When should you plant Kale (Winterbor) in your zone?
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Example Kale (Winterbor) timeline · Pittsburgh, PA (Zone 6b)
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Plant Kale (Winterbor)
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Kale (Winterbor)
Around Jun 11≈ 55 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Kale (Winterbor) dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 2-10, exceptional cold tolerance makes it ideal for zones 3-9
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Seedling
2-3 weeksTiny plants with 2-4 true leaves emerge within 7-10 days. Cotyledons are pale green and heart-shaped.
Provide bright light to prevent leggy growth. Keep soil consistently moist but not soggy. Thin seedlings to strongest individual at 3-4 true leaves.
Vegetative Growth
3-4 weeksPlant develops its characteristic deeply frilly, curled foliage. Leaves emerge progressively upward along central stem with increasingly complex serration patterns.
Maintain consistent watering and weekly feeding with balanced fertilizer. Remove yellowed lower leaves. Watch for pest pressure during warm weather.
Leaf Development
3-5 weeksFull, mature leaf structure with dense, blue-green coloration. Plant reaches 12-18 inches tall. Leaves become increasingly tender and nutritious.
Begin selective harvest of outer leaves once they reach 8-12 inches. Side-dress with compost every 2-3 weeks. Maintain adequate spacing for air circulation.
Cold Hardening
Ongoing through winterAfter first frost exposure (around 28°F or below), leaves develop enhanced sweetness, color deepens to darker blue-green, and texture becomes more tender. Plant can withstand repeated freeze-thaw cycles.
Discontinue nitrogen fertilizer. Light frosts actually improve flavor—no protection needed until temps drop below 20°F. Plant remains productive through winter in mild climates.
Peak Harvest
4-8 weeks or until springPlant is at maximum tenderness, sweetness, and nutritional density. Lower leaves continue to mature while new leaves form at top. Plant maintains productivity for 2-3 months post-frost.
Harvest regularly to encourage continued production. Pick outer leaves first; central leaves will continue developing. Remove any yellowed or damaged foliage.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Hand-pick caterpillars; use Bacillus thuringiensis (Bt) spray; encourage parasitic wasps; row covers for young plants
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Row covers until plants establish; neem oil spray; diatomaceous earth; reflective mulch; strong water spray to dislodge
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Fine mesh netting; hand-pick eggs from leaf undersides; Bt spray; encourage native parasitoid wasps
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Strong water spray; insecticidal soap; neem oil; encourage ladybugs and lacewings; reflective mulch
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Yellow sticky traps; reflective mulch; neem oil spray; encourage beneficial insects; row covers
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Root barriers/collars around seedlings; row covers; crop rotation; parasitic wasp Opius colonization
Uses
Raw Salads & Smoothies
CulinaryWinterbor kale is exceptionally tender and mild compared to other varieties, making it excellent for raw consumption. Use young leaves in salads or blend into smoothies and juices for a nutrient-dense beverage. [source]
Sautéed Greens & Soups
CulinaryLarger leaves are ideal for sautéing, stir-frying, or adding to soups and stews. The tender texture cooks down quickly, making it a versatile addition to warm dishes. [source]
Nutritional & Antioxidant Content
MedicinalKale is exceptionally rich in vitamins A, C, and K, calcium, iron, and glucosinolates—compounds with documented anti-inflammatory and potential anti-cancer properties. Freezing actually enhances bioavailability of certain nutrients. [source]
Natural Dye Source
HouseholdFresh or dried kale leaves can be processed into a natural dye yielding shades of green and yellow-green for fabric dyeing projects. [source]
Pollinator & Beneficial Insect Support
WildlifeIf a small portion is allowed to bolt and flower in spring, kale produces delicate yellow flowers that attract honeybees, native bees, and other pollinators. Flowers also attract parasitoid wasps that control pest insects. [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 they reach 8-12 inches long (about 3-4 weeks after transplanting). Pinch or cut leaves at the base where they meet the stem; never remove more than 1/3 of plant at once. Flavor and tenderness improve after light frosts (28-32°F). Peak harvest occurs in fall through early winter. Lower leaves mature first; central leaves will continue developing for weeks. Regular harvesting encourages continued leaf production. Winterbor can remain productive for 3-4 months if properly maintained.
Fun Facts
- 🌱 Winterbor was developed in Denmark and is prized by Northern European growers for its exceptional cold hardiness—it can survive temperatures down to -13°F (-25°C) with snow cover and actually becomes sweeter after multiple freeze-thaw cycles as starches convert to sugars.
- 🌱 Kale contains more vitamin K per calorie than almost any other food; a single cup of raw Winterbor provides over 1000% of daily recommended intake, essential for bone health and blood clotting.
- 🌱 The name 'Winterbor' combines 'Winter' (reflecting its cold-season vigor) and 'bor' (from the Danish word for cabbage/brassica), and this variety was specifically bred to extend the harvest season in short-season climates.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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