Kale

Introduction

Kale has enjoyed a resurgence in popularity thanks to its versatility, nutrition, and ability to thrive in the UK climate. A hardy brassica, it tolerates cold weather and often improves in flavour after frost, making it one of the best winter greens. With a wide range of varieties-from curly to flat-leaved, dwarf to tall-kale can be harvested over many months. It’s easy to grow in beds, borders, or containers and provides a reliable crop when other vegetables are scarce.

Types and Timing

Kale varieties vary in flavour, leaf shape, and season:

• Curly kale: Classic, frilly leaves in green or purple (‘Winterbor’, ‘Redbor’).

• Cavolo Nero (Tuscan kale, black kale): Tall plants with long, dark, strap-like leaves.

• Dwarf kales: Compact, ideal for windy sites or smaller spaces.

• Russian kales: Flat, tender leaves with reddish tinge, often sweeter.

Timing:

• Sow indoors from March to May.

• Direct sow outdoors from April to June.

• Plant out seedlings from May to July.

• Harvest from autumn through to spring, depending on variety.

Site and Soil Requirements

Kale is undemanding but benefits from fertile, well-prepared soil:

• Light: Prefers full sun but tolerates partial shade.

• Soil: Moist, fertile, and well-drained. Add compost or well-rotted manure before planting.

• pH: Neutral to slightly alkaline-lime the soil if very acidic to reduce clubroot risk.

• Containers: Can be grown in large pots (30 cm+) with rich compost.

Propagation & Planting

• Sowing indoors: Sow in modules or pots 1 cm deep, then transplant when seedlings are 7-10 cm tall.

• Direct sowing: Sow in drills 1 cm deep, thin to 7-10 cm apart, then transplant to final positions.

• Spacing: 45 cm between plants, 60 cm between rows (dwarf types can be closer).

• Transplanting: Plant deeply and firm soil around roots to prevent rocking in the wind.

• Succession: Sow every few weeks until mid-summer for staggered cropping.

Growing & Maintenance

• Watering: Keep soil evenly moist, especially in dry spells, but avoid waterlogging.

• Feeding: A nitrogen-rich liquid feed during summer encourages leafy growth.

• Mulching: Retains moisture and suppresses weeds.

• Weeding: Essential to reduce competition for nutrients.

• Protection: Use netting to protect from pigeons and caterpillars.

• Harvesting leaves: Pick outer leaves regularly to keep plants producing new growth.

Harvest and Post-Harvest

• Timing: Harvest from September through winter, often lasting into March.

• Picking method: Harvest outer leaves as needed (“cut-and-come-again”), leaving the central bud to keep producing.

• Frost benefit: Cold weather sweetens the leaves.

• Storage: Best eaten fresh but can be stored in the fridge for up to a week. Blanch and freeze for long-term use.

• Cooking: Use in soups, stir-fries, steamed, or baked into crisps.

Troubleshooting & Pests

• Cabbage white butterflies: Caterpillars strip leaves-use fine mesh netting.

• Pigeons: Can devastate crops-protect with netting or fleece.

• Clubroot: Soil-borne disease causing swollen roots. Prevent by liming acidic soil and rotating crops.

• Aphids: Gather on young leaves-squash, wash off, or encourage predators.

• Bolting: Hot, dry conditions may cause early flowering-keep plants well watered.

Tips from Growers / FAQs

• Best for beginners: Curly kale is hardy, productive, and forgiving.

• Winter harvests: Cavolo Nero withstands frost well and looks striking in the garden.

• Continuous supply: Grow a mix of early, main, and late varieties for harvests spanning 6-8 months.

• Cut-and-come-again: Regular picking prolongs productivity and keeps plants tidy.

• Container growing tip: Use dwarf varieties for pots, feeding every few weeks for best results.

Resources & References

• RHS: Grow Your Own Kale

• BBC Gardeners’ World: How to Grow Kale