Growing, harvesting and storing leeks

Leeks may be slow to grow, but with the right planting system, balanced nutrition, and proper post-harvest handling, they deliver high yields and excellent storage life. Here’s a complete guide for growers who want consistent quality and long white stems.

Leek Cultivation and Storage: Best Practices for High-Quality Yields

Leeks have been cultivated in the Mediterranean for more than 4,000 years. They are valued for their mild flavor, nutritional benefits, and versatility in soups, casseroles, and fresh salads. Although the crop requires a long growing period - 21 to 30 weeks - the right approach ensures excellent yields and storability.

Growing Requirements

Leeks grow best at 15–25°C, tolerate frost well, and perform poorly in extreme heat. They adapt to various soil types, but well-drained, neutral to slightly alkaline soils offer the best results.

Planting

• The main production season runs from April to November, though some regions can grow leeks year-round.

• Planting seedlings is preferred for precise spacing and uniform development.

• Field beds:

  • Raised beds: 1.5 m wide for improved drainage

  • Rows: 4 rows per bed, 40 cm apart

  • Depth: transplant seedlings 10–15 cm deep (deeper planting = longer white stems)

Modern varieties, developed by international breeding companies, focus on longer white stems, smaller bulbs, and darker leaves.

Fertilisation and Irrigation

Before planting, apply compost (up to 50 m³/ha) and enrich the soil with magnesium, manganese, boron, copper, zinc, and other trace elements.

Recommended program:

• Before planting: double superphosphate (0.6 t/ha)

• After planting: weekly nitrogen and potassium via irrigation

• 4 weeks after planting: magnesium sulfate (50 kg/ha)

• If deficiencies appear:

  • Zinc sulfate spray (4 g/L)

  • Iron chelate (2 g/L)

Always adjust nutrition according to soil and water analyses. Over-fertilisation harms both quality and yield.

Pests and Diseases

Leeks are relatively resistant, but several threats require monitoring:

Pests

• Onion fly

• Caterpillars

• Thrips

• Snails (especially early-season)

Diseases

• Fusarium wilt — increased risk with continuous monocropping

• Bacterial soft rot — common in cool, wet conditions

• Mechanical damage during hot periods can open entry points for bacteria

Proper rotation and careful handling significantly reduce risk.

Harvesting and Storage

For long-term storage, leeks should be harvested by hand to avoid mechanical injuries. After harvesting:

1. Trim roots

2. Trim leaf tops (leave 10–15 cm)

3. Rinse thoroughly

High-quality leek characteristics:

• White stem: 10–20 cm

• Bulb diameter: 2–5 cm

• Weight: 200–300 g

• Dark green leaves

Storage parameters:

• Temperature: 0–2°C

• Relative humidity: 90–95%

• Storability: up to 90+ days

Want to Learn More?

Explore more articles on vegetable storage, climate control, and post-harvest technologies on our blog - or review our completed storage projects. For consultations: +971504377119 or info@agrovent.com