Kale 'Winterbor F1'
Brassica oleracea var. acephala 'Winterbor F1'
The ultimate winter kale that actually improves in flavor after frost exposure, becoming sweeter and more tender. This vigorous hybrid produces masses of deeply curled, blue-green leaves that can withstand temperatures down to 10°F while continuing to grow. It's the go-to variety for gardeners wanting fresh greens throughout winter.
Harvest
60-65d
Days to harvest
Sun
Full sun to partial shade
Zones
6–9
USDA hardiness
Height
10-24 inches
Planting Timeline
Showing dates for Kale 'Winterbor F1' in USDA Zone 7
All Zone 7 brassica →Zone Map
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Kale 'Winterbor F1' · Zones 6–9
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | March – April | May – June | May – June | July – October |
| Zone 4 | March – April | May – June | April – June | June – October |
| Zone 5 | February – March | April – May | April – May | June – November |
| Zone 6 | February – March | April – May | April – May | June – November |
| Zone 7 | February – March | April – May | March – May | May – November |
| Zone 8 | January – February | March – April | March – April | May – December |
| Zone 9 | January – January | February – March | February – March | April – December |
| Zone 10 | January – January | February – March | January – March | March – December |
Complete Growing Guide
Light: Full sun (6 or more hours of direct sunlight a day), Partial Shade (Direct sunlight only part of the day, 2-6 hours). Soil: Clay, Loam (Silt), Sand. Soil pH: Acid (<6.0), Neutral (6.0-8.0). Drainage: Good Drainage, Moist. Height: 0 ft. 10 in. - 2 ft. 0 in.. Spread: 1 ft. 0 in. - 2 ft. 0 in.. Spacing: 12 inches-3 feet. Growth rate: Medium. Maintenance: Medium. Propagation: Seed, Stem Cutting. Regions: Coastal, Mountains, Piedmont.
Harvesting
The fruits dry and split when ripe.
Color: Brown/Copper, Green. Type: Siliqua. Length: > 3 inches.
Garden value: Edible
Harvest time: Fall, Summer
Bloom time: Spring, Summer
Edibility: The foliage is edible raw or cooked but when cooked can emit an unpleasant odor.
Storage & Preservation
Fresh Winterbor leaves store best unwashed in perforated plastic bags in your refrigerator's crisper drawer, maintaining quality for 7-10 days. The thick, curled leaves hold up better than smooth kale varieties, making this excellent for meal prep.
For longer storage, blanch leaves in boiling water for 2 minutes, shock in ice water, then freeze in portions. Frozen Winterbor retains its texture better than most kales and works perfectly in smoothies and cooked dishes for up to 8 months.
Dehydrating creates excellent kale chips – massage leaves with olive oil and salt, then dehydrate at 115°F until crisp. The naturally sweet flavor of frost-touched Winterbor makes superior chips compared to summer-harvested kale. You can also ferment chopped Winterbor as part of sauerkraut blends, where its sturdy leaves maintain texture throughout the fermentation process.
History & Origin
Winterbor F1 was developed by Bejo Seeds in the Netherlands during the 1990s as part of their cold-hardy vegetable breeding program. Dutch plant breeders specifically created this hybrid to extend the fresh vegetable season in northern European climates, combining the winter hardiness of Siberian kale with the culinary appeal of curly kale varieties.
The 'F1' designation indicates this is a first-generation hybrid, carefully bred to maximize cold tolerance while maintaining consistent leaf quality and flavor. Bejo's breeding program focused on developing vegetables that could withstand increasingly unpredictable weather patterns, making Winterbor part of a new generation of climate-adaptive crops.
Since its introduction to North American markets in the early 2000s, Winterbor has become the gold standard for winter kale production. Its development represents a significant advancement in extending growing seasons naturally, without requiring greenhouse protection, making fresh winter vegetables accessible to more gardeners across diverse climate zones.
Advantages
- +Attracts: The foliage is edible raw or cooked but when cooked can emit an unpleasant odor.
- +Wildlife value: It serves as a host plant for butterflies, moths, flies, sawflies and beetles.
- +Edible: The foliage is edible raw or cooked but when cooked can emit an unpleasant odor.
Companion Plants
Plant Together
Nasturtiums
Acts as trap crop for aphids and flea beetles, protecting kale from pest damage
Onions
Repels cabbage worms, aphids, and flea beetles with strong sulfur compounds
Marigolds
Deters cabbage worms and aphids while attracting beneficial predatory insects
Dill
Attracts beneficial wasps that parasitize cabbage worms and improves kale flavor
Carrots
Utilizes different soil depths and nutrients, maximizing garden space efficiency
Lettuce
Benefits from kale's shade in hot weather and has compatible root systems
Garlic
Natural fungicide properties help prevent clubroot and other soil-borne diseases
Spinach
Similar growing conditions and acts as living mulch to retain soil moisture
Keep Apart
Strawberries
Competes for similar nutrients and attracts slugs that also damage kale leaves
Tomatoes
Heavy feeder that competes for nutrients and may stunt kale growth
Pole Beans
Can shade kale excessively and compete for nitrogen despite nitrogen-fixing ability
Nutrition Facts
Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #168421)
Pests & Disease Resistance
Resistance
Excellent cold tolerance, good resistance to downy mildew
Common Pests
Cabbage worms, aphids, flea beetles, leaf miners
Diseases
Downy mildew, black rot, white rust, clubroot