Leek (Allium ampeloprasum var. porrum) is a hardy, cool-season vegetable known for its long, thick white stalks and mild onion-like flavor. It is a versatile ingredient used in soups, stews, and sautés. Leeks are easy to grow, resistant to many pests and diseases, and can be harvested over a long period.

How to Grow Leeks

Sowing and Germination

• Starting Indoors:

  • Sow seeds indoors 8–10 weeks before the last frost in seed trays or pots.
  • Plant seeds 1/4 inch deep in well-draining soil.
  • Maintain a temperature of 60–75°F for optimal germination.
  • Thin seedlings to 1 inch apart when they reach 3 inches tall.

• Direct Sowing:

  • In mild climates, sow seeds directly outdoors in early spring or late summer for a fall crop.
  • Space seeds 1/4 inch deep and 1 inch apart in rows 12 inches apart.

Transplanting:

• When seedlings reach 6–8 inches tall, transplant them into trenches 6 inches deep.
• Space plants 4–6 inches apart in rows 12–18 inches apart.
• Gently fill in the trench with soil as the leeks grow to encourage long, white stems.

Soil Requirements:

• Prefers rich, well-drained, loamy soil with a pH of 6.0–7.0.
• Incorporate compost or organic matter before planting for better growth.

Sunlight:

• Requires full sun (at least 6 hours per day).
• Can tolerate partial shade, but growth may slow.

Growing Leeks

Watering:

• Water consistently to keep the soil evenly moist, about 1 inch per week.
• Avoid waterlogging, as excess moisture can cause rot.

Mulching:

• Apply a light layer of mulch to retain moisture and suppress weeds.

Fertilizing:

• Feed leeks with a balanced fertilizer (such as 10-10-10) every 3–4 weeks during the growing season.
• Boost with compost or organic fertilizer to promote healthy growth.

Blanching for Longer White Stems:

• To produce longer white stalks, gradually hill soil around the base of the plant as it grows.
• Alternatively, use paper collars or tubes to block sunlight from the lower stem.

Pest and Disease Management:

• Common pests: Leek moths, onion thrips, and aphids—use row covers or neem oil to control them.
• Ensure good air circulation and avoid overcrowding to prevent fungal diseases.
• Rotate crops yearly to prevent soil-borne diseases like onion rust.

Fast Facts

• Latin Name: Allium ampeloprasum var. porrum
• Type: Biennial (grown as an annual)
• USDA Zones: 3–10
• Days to Germination: 7–14 days
• Days to Maturity: 90–120 days
• Height: 12–18 inches
• Spacing: 4–6 inches apart
• Soil pH: 6.0–7.0
• Color: Light Green to White Stems

How and When to Harvest Leeks

• Harvest when stems are at least 1 inch thick, typically 90–120 days after planting.
• Use a garden fork to gently lift leeks from the soil to avoid damaging them.
• For a continuous harvest, start picking young leeks when they reach pencil thickness and allow others to grow to full size.
• In mild climates, leeks can be left in the ground and harvested as needed.

Leek Seed Saving

• Leeks are biennials, meaning they produce seeds in their second year.
• Allow some plants to flower and go to seed. Once seed heads dry, collect and store them in a cool, dry place.
• Properly stored seeds remain viable for 2–3 years.

Leeks are a low-maintenance, nutritious, and flavorful addition to any garden. With proper care, they provide a steady harvest for soups, sautés, and gourmet dishes all season long! 🌱