Brassica oleracea var. sabellica 'Winterbor' (Winterbor Kale)
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Brassica oleracea var. sabellica 'Winterbor' (Winterbor Kale)
Contents
- Introduction & History
- Botanical Description
- Varieties & Selection
- Planting & Sowing
- Climate & Hardiness
- Growing & Training
- Watering & Feeding
- Propagation & Seed Saving
- Diseases & Pests
- Companion Planting & Crop Rotation
- Container Growing
- Harvesting & Storage
- Culinary Uses & Nutrition
- Preserving & Fun Facts
- Seasonal Care Calendar
- Frequently Asked Questions
Introduction & History
Winterbor Kale (Brassica oleracea var. sabellica 'Winterbor') is a biennial brassicas vegetable in the Brassicaceae family, growing to 70 cm tall with a 50 cm spread. Its nutritious leaves can be first harvested in approximately 55 days from sowing. Hardy in USDA zones 2-11, it thrives in full sun to partial shade with moderate watering and prefers soil pH 6.0-7.5.
Harvested part: leaves • USDA zones: 2-11 • Sowing: both
Chromosome count: 2n=18 (B. oleracea) • Pollination: self-incompatible, insect-pollinated • Key secondary metabolites: glucosinolates (responsible for pungent flavour and anti-cancer properties)
All cultivated brassicas derive from wild cabbage through centuries of selective breeding
History & Origin
The Brassica family represents one of humanity's greatest feats of selective breeding. From a single wild species (Brassica oleracea) on European Atlantic coasts, gardeners developed cabbage, broccoli, cauliflower, kale, kohlrabi, and Brussels sprouts — each selecting for different plant parts. Winterbor Kale has been cultivated as a valued garden variety, selected for its blue-green leavess and reliable performance across a range of growing conditions.
Botanical Description
Brassica oleracea var. sabellica 'Winterbor' is a biennial member of Brassicaceae, forming a bushy/compact plant reaching 70 cm tall. The edible leaves are green, harvested as the primary crop. The root system is moderately spreading with fibrous roots.
| Height | 70 cm |
| Spread | 50 cm |
| Growth habit | Biennial |
| Foliage | green |
| Flowers | yellow |
| Fruit colour | blue-green |
| Fruit shape | curly leaves |
| Harvested part | leaves |
Varieties & Selection
Within the Brassica genus, numerous varieties have been developed for different climates, uses, and growing conditions. Choose varieties matched to your season — spring/summer types bolt quickly in heat, while winter varieties withstand hard frosts but need longer growing periods.
Selection Criteria
Select brassica varieties based on harvest season — early, mid-season, and late varieties provide year-round supply. Clubroot resistance (marked 'CR' on labels) is essential in infected soils. For broccoli, choose varieties with good side-shoot production for extended harvest after the main head is cut. Purple sprouting broccoli varieties bridge the 'hungry gap' (late winter/early spring).
Planting & Sowing
Grow in full sun in well-drained, fertile soil with pH 6.0-7.5. Plant both when soil reaches 8°C. Space plants 50 cm apart in rows 60 cm apart.
| Sun requirement | Full Sun To Partial Shade |
| Soil pH | 6.0-7.5 |
| Sowing method | Both |
| Sowing depth | 1.5 cm |
| In-row spacing | 50 cm |
| Row spacing | 60 cm |
| Germination temp | 10-25°C (optimum) |
| Days to germination | 7 days |
| Min soil temperature | 8°C |
| Water needs | Moderate |
Soil Preparation
Brassicas are heavy feeders requiring nitrogen-rich, moisture-retentive soil with a pH of 6.5–7.5. Liming acidic soils serves dual purposes: providing calcium for growth and raising pH above 7.0 to suppress clubroot. Incorporate blood and bone meal or pelleted chicken manure at planting, supplemented with liquid seaweed every 2–3 weeks during active growth. Firm soil is essential — brassicas in loose soil develop weak root systems and topple ('wind rock'), especially Brussels sprouts and tall kale varieties.
Climate & Hardiness
Winterbor Kale grows in USDA zones 2-11 and tolerates temperatures down to -10°C. This is a cold-hardy crop that can overwinter in many climates with minimal protection.
🌍 Origin Map
Origin: Europe, Mediterranean
Growing & Training
Winterbor Kale grows as a self-supporting bush and requires no special training or staking.
Group-Specific Growing Guide
Brassicas thrive in cool conditions (15–20°C) and suffer in heat above 25°C. They are heavy feeders requiring high nitrogen and consistent moisture. Clubroot (Plasmodiophora brassicae) is a devastating soil-borne disease that persists for 15+ years — maintain soil pH above 7.0 and practice strict crop rotation. Brassicas share a self-incompatibility system that prevents inbreeding, making isolation distances important for seed saving (1,000m+ for cross-pollinating types). Glucosinolates — the compounds responsible for the characteristic brassica flavour — break down into isothiocyanates when cells are damaged, which have demonstrated anti-cancer properties in epidemiological studies.
Watering & Feeding
Watering
Water deeply once or twice per week, allowing the top 2-3 cm of soil to dry between waterings. Increase frequency during heatwaves and fruiting. Consistent moisture prevents cracking and blossom end rot.
Feeding
Heavy feeder. Prepare beds with generous compost. Apply balanced granular fertilizer at planting, then side-dress with nitrogen every 3-4 weeks. Brassicas are particularly hungry for calcium and boron.
Propagation & Seed Saving
Seed saving difficulty: moderate. Brassicas cross-pollinate by insects — cage or isolate by 1km+ for pure seed. Most are biennial, flowering in year 2 after vernalization.
Seed Saving — Detailed Guide
Brassicas are self-incompatible and require cross-pollination by insects between different plants of the same variety. This means you need multiple plants (minimum 6–12) to produce viable seed with genetic diversity. All Brassica oleracea subspecies (broccoli, cauliflower, cabbage, kale, kohlrabi, Brussels sprouts) will cross with each other — grow only one variety for seed, or isolate by 1,000+ metres. Most brassicas are biennial: overwintered plants bolt in spring, producing tall racemes of yellow four-petalled flowers followed by long thin pods (siliques). Harvest pods when they turn brown and papery, before they shatter. Viability: 4–5 years.
Diseases & Pests
Common Diseases
Clubroot (Plasmodiophora brassicae): Swollen, distorted roots, wilting in sun. Raise soil pH to 7.2+, rotate 7+ years, use resistant varieties. Black Rot (Xanthomonas campestris): V-shaped yellow lesions from leaf edges. Use clean seed, hot-water treat seed, 3-year rotation. Downy Mildew: Yellow patches on upper leaf, grey mold below. Improve airflow, avoid overhead watering. Ring Spot / Alternaria: Dark concentric ring spots on leaves. Remove debris, rotate crops, apply fungicide if severe. White Blister / White Rust: White raised pustules on leaf underside. Remove affected leaves, improve air circulation.Group Disease Reference (Brassica)
- Clubroot (Plasmodiophora brassicae) — swollen, distorted roots; lime soil to pH 7.2+; 15-year soil persistence; no effective chemical control
- Downy mildew (Hyaloperonospora parasitica) — yellowish patches on upper leaves, grey-white mould beneath; improve air circulation; resistant varieties
- Black rot (Xanthomonas campestris pv. campestris) — V-shaped yellow lesions from leaf margins; use disease-free seed; hot water seed treatment (50°C for 25 min)
- Alternaria leaf spot — dark concentric rings on older leaves; remove debris; crop rotation
Group Pest Reference
- Cabbage white butterfly (Pieris rapae/brassicae) — green caterpillars devastate leaves; fine mesh netting (Enviromesh) is the most effective organic control; Bt spray
- Cabbage root fly (Delia radicum) — larvae destroy roots of transplants; root collars or brassica collars; fleece immediately after transplanting
- Flea beetle (Phyllotreta spp.) — tiny shot-holes in leaves of seedlings; fleece cover; keep seedlings growing vigorously
- Mealy cabbage aphid (Brevicoryne brassicae) — waxy grey colonies; check undersides of leaves regularly; squash or hose off
1. Cultural controls — crop rotation, resistant varieties, proper spacing, good hygiene (remove debris, sterilise tools)
2. Physical controls — insect mesh, fleece barriers, slug traps, hand-picking, companion planting
3. Biological controls — encourage natural predators (ladybirds, lacewings, hoverflies, ground beetles); use parasitic wasps, nematodes, or Bt spray
4. Chemical controls — last resort only; organic options (neem oil, pyrethrum, copper fungicide, insecticidal soap) before synthetic products
Companion Planting & Crop Rotation
Companion planting works through multiple mechanisms: aromatic plants repel pests (basil deters whitefly on tomatoes), deep-rooted plants break compaction for shallow-rooted neighbours, and nitrogen-fixing legumes enrich soil for heavy-feeding brassicas.
Antagonistic relationships include allelopathy (chemical growth inhibition), shared pest/disease vulnerability, and direct competition for the same soil nutrients or root zone space.
Crop Rotation
Winterbor Kale belongs to no specific rotation group. It can be fitted into most rotation schemes flexibly. Avoid planting in the same spot annually to prevent soil-borne disease buildup.
Container Growing
Winterbor Kale is not ideally suited for containers due to its deep root system. If attempted, use the largest container possible (60+ cm diameter) with support.
• Drainage: Ensure generous drainage holes; use crocks or mesh at the base to prevent compost washout
• Feeding: Container compost nutrients deplete in 6–8 weeks; begin liquid feeding fortnightly from this point
• Watering: Check moisture daily; the 'finger test' (dry to 2 cm depth = water needed) prevents both over- and under-watering
• Position: Most vegetables need 6+ hours of direct sunlight; rotate containers weekly for even growth
• Insulation: In hot weather, double-pot (pot inside a larger pot with insulating gap) to prevent root overheating
Harvesting & Storage
Harvest Winterbor Kale when leavess reach full size but before over-maturity. Begin harvesting outer leaves when plants are well-established, approximately 55 days after sowing. Cut-and-come-again harvesting extends the productive period significantly.
Group Harvest Guide — Brassica
Harvest timing is critical for brassica quality. Broccoli heads should be cut while florets are still tight and before any yellow flowers appear — once flowering begins, flavour deteriorates rapidly. Cut the central head first, then side shoots develop for a second harvest. Cauliflower curds should be white, firm, and compact; blanch by folding outer leaves over the curd when it reaches 5 cm diameter. Brussels sprouts are harvested from the bottom of the stem upwards as they mature; frost improves their sweetness. Kale leaves can be harvested continually through winter — take outer leaves and leave the growing point intact.
Storage
Store Winterbor Kale in fresh conditions. Expected storage life: 1 weeks under optimal conditions. Wrap loosely in damp paper towels in a perforated bag in the refrigerator crisper. Use within 5-7 days.
Preservation Methods
Freezing: Blanch 2 minutes, squeeze dry, freeze in portions. Drying: Dehydrate at 46°C for 4-8 hours (crumble for seasoning). Pesto/paste: Blend with oil and freeze in ice cube trays for year-round use.
Culinary Uses & Nutrition
Overcooking releases sulfurous compounds (the 'cabbage smell'). Brief cooking (under 7 minutes) preserves sweetness and nutrients. Fermenting (sauerkraut, kimchi) creates probiotics and preserves vitamin C through winter. Winterbor Kale is a versatile ingredient used across multiple cuisines.
Preserving, Succession & Planning
Freezing: Blanch 2 minutes, squeeze dry, freeze in portions. Drying: Dehydrate at 46°C for 4-8 hours (crumble for seasoning). Pesto/paste: Blend with oil and freeze in ice cube trays for year-round use.
Year-Round Growing Calendar
Maximise your productivity with Brassica oleracea var. sabellica 'Winterbor' by planning across the full year:
- Late winter (Feb–Mar): Order seeds, clean and repair equipment, plan crop rotations, start indoor sowings for warm-season crops
- Spring (Apr–May): Direct sow hardy crops, transplant indoor-started seedlings after hardening off, apply compost and mulch
- Summer (Jun–Aug): Main growing and harvesting season; succession sow for autumn; water consistently; monitor for pests
- Autumn (Sep–Nov): Harvest storage crops, sow overwintering varieties, clear spent plants, incorporate green manures
- Winter (Dec–Jan): Process and store harvests, plan next season, maintain tools, order seed catalogues
Frequently Asked Questions
How long does it take to grow Winterbor Kale?
Winterbor Kale typically takes approximately 55 days from planting to harvest, depending on variety, climate, and growing conditions.
What are the best growing zones for Winterbor Kale?
Winterbor Kale grows well in USDA hardiness zones 2-11. In colder zones, start seeds indoors and transplant after the last frost.
Can I grow Winterbor Kale in containers?
Winterbor Kale is better suited to open ground due to its size, but can be grown in large containers (60+ cm diameter).
When should I plant Winterbor Kale?
Direct sow outdoors after all frost risk has passed and soil temperature reaches 8°C.
What pests affect Winterbor Kale?
cabbage white butterfly (Pieris brassicae), cabbage moth, flea beetles, aphids (mealy cabbage), cabbage root fly, slugs, whitefly, diamond-back moth
Seasonal Care Calendar
🌱 Spring (Mar–May)
Water: Regular as growth resumes
Feeding: Apply compost and balanced feed
Direct sow or transplant. Protect from late frosts with fleece. Begin succession sowing.
☀️ Summer (Jun–Aug)
Water: Consistent deep watering
Feeding: Regular liquid feed
Peak harvest. Continue succession sowing for autumn crops. Monitor for pests and diseases.
🍂 Autumn (Sep–Nov)
Water: Reduce gradually
Feeding: Final feed early autumn
Late harvest. Protect with cloches for extended season. Sow overwintering varieties.
❄️ Winter (Dec–Feb)
Water: Minimal
Feeding: None
Harvest overwintered crops. Maintain cold frames. Plan rotations and order seeds.