How to Grow Cos Lettuce Valmaine

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Cos Lettuce Valmaine

Lactuca sativa var. longifolia

vegetable

Valmaine is a classic romaine/cos lettuce variety known for its tall, upright growth habit and crisp, tender leaves with excellent flavor. It produces dense, elongated heads with dark green outer leaves and pale, blanched inner leaves ideal for Caesar salads and fresh eating.

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Example Cos Lettuce Valmaine timeline · Pittsburgh, PA (Zone 6b)

Plant Cos Lettuce Valmaine
Around Apr 17

Near Pittsburgh's average last spring frost.
Tend & protect
Late spring–summer

Watering, feeding, and pest-watch reminders.
Harvest Cos Lettuce Valmaine
Around Jun 16

≈ 60 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Cos Lettuce Valmaine dates for your own zip code.

Growing Conditions

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Sun: Full sun (6+ hours daily), though it appreciates afternoon shade in hot climates above 75°F

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Water: Keep soil consistently moist but not waterlogged; provide 1-1.5 inches of water per week. Water deeply at the base to prevent fungal issues on leaves. More frequent watering needed in hot weather.

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Spacing: 6-8 inches apart for mature heads; thin seedlings to this spacing early inches

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Days to maturity: 60-75 days from seed; 45-50 days from transplant

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Planting depth: 0.25-0.5 inches; seeds are tiny and should be barely covered

Soil

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

pH: 6.0-7.0

Amendments:

Compost aged manure peat moss or coir balanced slow-release fertilizer

Growing Zones

Find your zone →

Thrives in zones 3-9; can be grown year-round in mild climates

2a 2b 3a 3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b 9a 9b 10a

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Growth Stages

Seedling

2-3 weeks

Tiny cotyledons emerge in 7-10 days; first true leaves appear narrow and delicate

Keep soil consistently moist; provide bright light; thin seedlings at 2-3 leaf stage if direct sowing. Avoid oversaturation to prevent damping off.

Vegetative Growth

3-4 weeks

Plant develops multiple true leaves in an upright rosette pattern; no head formation yet

Thin to final spacing; ensure consistent moisture and fertility; apply balanced fertilizer every 3 weeks. Maintain cool temperatures (60-70°F ideal) for crisp texture.

Head Formation

2-3 weeks

Leaves begin to overlap and form a loose, elongated head; plant becomes more compact and dense

Continue consistent watering; reduce nitrogen to encourage head closure; monitor for bolting if temperatures rise above 75°F. Some varieties benefit from tying outer leaves to blanch inner leaves.

Mature Head

1-2 weeks at peak quality

Full, firm, upright head forms with pale inner leaves and darker green outer leaves; 8-10 inches tall

Maintain moisture; watch for tip burn (calcium deficiency) by keeping soil evenly moist; harvest before bolting begins. Valmaine is bolt-tolerant compared to other romaines.

Harvest

Ongoing during harvest window

Mature heads ready for cutting; leaves are crisp and full of flavor

Harvest in early morning for maximum crispness; cut at soil line or remove outer leaves for continuous harvest. Cool immediately after cutting.

Companion Planting

Plan your garden →

Plant with:

Basil Beets Carrots Chives Dill Garlic Marigolds Nasturtiums Parsley Radishes Strawberries Swiss chard

Avoid planting near:

Cabbage Celery Fennel Parsnips

Common Pests

Spray with water to dislodge; use insecticidal soap or neem oil; encourage natural predators like ladybugs and lacewings
and
Hand-pick in early morning; use copper tape or diatomaceous earth barriers; remove dead leaves and mulch that harbor them; beer traps
Use reflective mulches; rotate crops; remove affected plants; apply beneficial nematodes to soil
Improve air circulation; avoid overhead watering; apply sulfur or copper fungicides; choose resistant varieties; remove infected leaves
Handpick caterpillars; use Bt (Bacillus thuringiensis); row covers for young plants; encourage parasitic wasps
Yellow sticky traps; spray undersides of leaves with insecticidal soap; neem oil; reflective mulches

Uses

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Caesar Salads & Classic Preparations

Culinary

Valmaine is the traditional romaine variety used in classic Caesar salads; its upright heads, crisp texture, and mild flavor make it ideal for fresh salads, wraps, and sandwich fillings. [source]

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Grilled Lettuce & Cooking

Culinary

The sturdy leaves and firm heads hold up well to grilling and roasting, offering a slightly bitter, caramelized flavor when charred. Can also be braised or wilted in warm dressings. [source]

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Nutritional & Antioxidant Benefits

Medicinal

Rich in vitamins A, K, and C, folate, and antioxidants including beta-carotene and lutein. Supports eye health, bone strength, and cardiovascular function. [source]

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Juice & Smoothie Base

Household

The pale inner leaves are mild and less bitter than other greens, making them excellent for fresh juicing, green smoothies, and blended detox drinks. [source]

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Habitat & Food Source

Wildlife

Flowering Valmaine lettuce plants provide nectar for pollinators and seeds for birds. Bolting plants also support beneficial insects and songbirds. [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 when heads are firm and upright, typically 60-75 days after sowing. Cut heads at soil level in the early morning for maximum crispness and water content. Valmaine can also be harvested as loose leaves once mature if continuous picking is desired. Cool immediately in ice water after harvest; the natural sugars and crispness are best within hours of picking.

Fun Facts

🌱 Valmaine was developed in France and is sometimes called 'Valmaine French' or 'Valmaine Improved'; it's considered one of the most bolt-tolerant and heat-tolerant romaine varieties, making it ideal for spring and fall crops
🌱 Romaine/cos lettuce is so-named because it was reintroduced to European cultivation from the Greek island of Cos (Kos); it has been cultivated since ancient Roman times and was a favorite of Roman legionaries
🌱 The pale inner leaves of Valmaine develop this blanched color naturally through shading by outer leaves; some gardeners tie outer leaves together to accelerate this blanching process, resulting in even more tender, sweeter inner leaves

Gardening Terms

New to gardening? Learn about terms used in this guide:

Bolt Damping Off Direct Sow Full Sun True Leaves

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