How to Grow Leek Carentan

Leek Carentan

Allium porrum 'Carentan'

vegetable

Carentan is a classic heirloom leek variety known for its long, thick, white shanks and tender, mild flavor. It is a cold-hardy French cultivar that was developed in Normandy and has been grown for centuries. This variety produces uniform, high-quality leeks ideal for culinary use.

Growing Conditions

☀️

Sun: Full sun, 6-8 hours daily; tolerates partial shade in very hot climates

💧

Water: Consistent moisture; water deeply 1-2 inches per week. Keep soil evenly moist but not waterlogged. More frequent watering during dry spells and heat.

📏

Spacing: 6-8 inches apart in rows; rows 12-18 inches apart inches

📅

Days to maturity: 120-150 days from transplant; longer if direct seeded

🌱

Planting depth: Seeds sown ¼ inch deep; transplants set 6-10 inches deep to blanch shanks

Soil

Type: Well-draining, fertile loamy soil rich in organic matter

pH: 6.0-7.0

Amendments:

Compost aged manure peat moss or coconut coir balanced organic fertilizer (5-10-5)

Growing Zones

Find your zone →

Thrives in zones 3-9; extremely cold-hardy and excellent for cool-season gardening

3a 3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b 9a 9b

Growth Stages

Seedling

4-6 weeks

Tiny grass-like leaves emerge; very delicate appearance with thread-thin stems

Keep soil consistently moist but not waterlogged. Provide bright light. Thin seedlings if crowded. Avoid transplant shock by hardening off gradually.

Transplant & Establishment

2-3 weeks

Young plants with 2-4 leaves, pencil-thin stems; ready for field planting

Harden off seedlings over 7-10 days before transplanting. Set deep (6-10 inches) in prepared rows. Water immediately after transplanting. Mulch lightly to retain moisture.

Vegetative Growth

8-12 weeks

Foliage expands; multiple upright leaves develop; underground stem thickens gradually

Water regularly and deeply. Fertilize every 3-4 weeks with balanced or slightly nitrogen-rich fertilizer. Hill up soil around base to blanch the shank (create white portion). Remove any flower buds that form.

Blanching & Maturation

4-6 weeks

White shank elongates and thickens; base may reach 2+ inches in diameter; leaves remain blue-green

Continue hilling soil around the stem to increase white blanched portion. Water consistently but avoid waterlogging. Reduce nitrogen fertilizer; apply potassium-rich fertilizer to harden plants for cold storage.

Harvest Ready

Extends into fall and winter

Shanks are thick, white, and uniform; plants are cold-hardy and hold well in field

Can be harvested anytime after 120 days. Carentan improves in flavor after light frost. Handle carefully to avoid bruising. Harvest by loosening soil and pulling gently or digging to avoid breaking stems.

Companion Planting

Plan your garden →

Plant with:

Carrot Celery Onion Beet Spinach Parsley Chamomile Dill

Avoid planting near:

Bean Pea Potato Fennel Garlic Other Allium species (in close proximity)

Common Pests

Use fine mesh netting to exclude adults. Handpick larvae if spotted. Apply spinosad or neem oil if infestation occurs. Remove and destroy infested plant material.
Row covers placed at transplant time. Proper spacing for air circulation. Remove affected plants. Diatomaceous earth around base of plants.
Spray with water to dislodge. Neem oil or insecticidal soap. Avoid excessive nitrogen fertilizer which promotes soft growth.
Ensure good air circulation and avoid overhead watering. Remove affected leaves. Fungicide spray with sulfur in severe cases. Resistant varieties if available.
Crop rotation (5+ years away from Alliums). Remove and destroy affected plants immediately. Sanitize tools. No chemical control available; prevention is key.

Uses

🍳

Soup & Stewing

Culinary

Carentan leeks have a mild, sweet, onion-like flavor and tender texture that makes them ideal for classic leek and potato soup, creamy bisques, and braised preparations. The blanched white shank is the most prized culinary part. [source]

🍳

Fresh & Roasted

Culinary

Slice lengthwise and roast with olive oil until caramelized for a elegant side dish. Also excellent grilled, braised, or served cold in salads and vinaigrettes. [source]

💊

Nutritional & Health Benefits

Medicinal

Leeks are rich in vitamins A, C, K, and folate, plus beneficial compounds like kaempferol and flavonoids. Traditionally used in herbal medicine for their prebiotic fiber and potential anti-inflammatory properties. [source]

🏠

Stock & Broth

Household

Leek greens and roots are excellent in vegetable stock and homemade broths, contributing subtle onion-like depth without overpowering flavor. Saves kitchen scraps and adds nutritional value. [source]

🍳

Vinaigrette & Cold Preparations

Culinary

Blanched leek sections are classic in French cuisine, especially in salad Niçoise and served cold with vinaigrette dressing. Tender and elegant when properly cooked and chilled. [source]

This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.

Harvest Tips

Harvest from late fall through winter when shank diameter reaches 1-1.5 inches or larger. Carentan is extremely frost-tolerant and flavor improves after frost. Loosen soil with a spade and gently pull plants out. Harvest in the morning when plants are crisp. To store, trim roots to ½ inch and remove yellowed outer leaves; keep in cool (32-40°F), humid conditions for 2-3 months.

Fun Facts

🌱 Carentan is a heritage variety developed in Normandy, France, dating back to at least the 18th century, and remains one of the most respected heirloom leek cultivars worldwide.
🌱 Leeks are extremely cold-hardy and can survive freezing temperatures; frost actually sweetens their flavor by converting starches to sugars, making them perfect for fall and winter harvests.
🌱 The blanched white shank develops through a process called 'earthing up' or 'hilling'—burying the lower stem beneath soil blocks sunlight and prevents chlorophyll formation, creating the prized tender, white, mild portion.

Want personalized planting timelines?

Get started free