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How to Grow Long Leaf Lettuce

Long Leaf Lettuce

Lactuca sativa var. longifolia

vegetable

Long Leaf lettuce, also known as romaine or cos lettuce, is a crisp, upright variety with elongated leaves that form loose to semi-tight heads. Prized for its tender texture, mild flavor, and nutritional value, it's a staple in salads and cooking. This cool-season crop is easy to grow and matures quickly in favorable conditions.

Looking for a specific variety?

Jericho Parris Island Cos Valmaine Muir Green Towers Coastal

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Example Long Leaf Lettuce timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Long Leaf Lettuce

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. Harvest Long Leaf Lettuce

    Around Jun 6

    ≈ 50 days after planting

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

Growing Conditions

☀️
Sun: Full sun to partial shade; 6+ hours of direct sunlight daily. Afternoon shade in hot climates helps prevent bolting.
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Water: Keep soil consistently moist but not waterlogged. Water deeply 1-2 times weekly depending on temperature and rainfall. Reduce watering frequency in cool weather.
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Spacing: 8-12 inches
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Days to maturity: 50-75 days
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Planting depth: 0.25-0.5 inches (seeds); transplants at soil level

Soil

Type: Well-draining loamy soil rich in organic matter
pH: 6.0-7.0
Amendments:
Compost aged manure peat moss perlite for drainage

Growing Zones

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Thrives in zones 3-9; best in cool seasons (spring and fall)

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

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Growth Stages

1

Seedling

7-14 days

Tiny seed leaves (cotyledons) emerge and first true leaves begin to develop. Plant is delicate and only 1-2 inches tall.

Keep soil moist, provide bright light (indoors use grow lights 2-3 inches above seedlings), maintain 60-70°F temperature. Thin seedlings when 2-3 inches tall.

2

Vegetative Growth

20-30 days

Leaves multiply and expand, forming the characteristic long, lobed leaf structure. Plant grows 6-12 inches tall with increasing leaf count.

Maintain consistent moisture, thin plants to proper spacing, provide full sun or dappled afternoon shade in warm weather. Remove any yellowing outer leaves. Apply light fertilizer (balanced 10-10-10) every 3 weeks.

3

Head Formation

15-25 days

Leaves begin clustering more densely, forming a loose to semi-tight head structure. Plant reaches 10-18 inches tall with 15-30 leaves visible.

Continue consistent watering without wetting foliage (prevents disease). Avoid overhead watering. Monitor for bolting; if flower stalk appears, harvest immediately or cut it off to extend harvest.

4

Maturity/Harvest-Ready

Harvest window 7-14 days

Leaves are fully developed, crisp, and tender. Head is compact and firm to light pressure. Plant reaches full size (12-20 inches tall) with rich green color.

Harvest outer leaves regularly to encourage continued growth, or harvest entire head. Water in morning to maximize crispness. Pick before temperatures exceed 75°F to avoid bitterness.

5

Bolting/End of Season

Onset signals end of harvest

Flower stalk emerges from center, leaves become bitter and tougher, plant diverts energy to reproduction.

Once bolting begins significantly, plant is past peak eating quality. Pull and compost, or cut flower stalks to extend harvest slightly. Plan succession plantings 2-3 weeks apart for continuous harvest.

Companion Planting

Plan your garden →

Plant with:

Radish Beet Carrot Onion Chives Parsley Dill Marigold Nasturtium Borage

Avoid planting near:

Cabbage Broccoli Celery Fennel Parsnip

Common Pests

  • Spray with water to dislodge; use insecticidal soap or neem oil. Introduce ladybugs. Avoid over-fertilizing with nitrogen.

  • and

    Hand-pick in early morning or evening. Use beer traps or copper tape barriers. Remove garden debris where they hide. Apply diatomaceous earth around base.

  • Yellow sticky traps; insecticidal soap; neem oil. Remove infected leaves immediately. Plant resistant varieties when available.

  • Remove affected leaves promptly. Use row covers on young plants. Yellow sticky traps. Spinosad spray as last resort.

  • Insecticidal soap, neem oil, or horticultural oil spray. Yellow sticky traps. Reflective mulch to confuse insects.

  • Hand-pick caterpillars. Bacillus thuringiensis (Bt) spray. Row covers for young plants. Remove crop debris after harvest.

Uses

🍳

Fresh Salads & Wraps

Culinary

Long Leaf lettuce is ideal for Caesar salads, lettuce wraps, and fresh green salads due to its crisp texture and mild flavor. The sturdy, elongated leaves also hold dressings and toppings well. [source]

🍳

Cooked Dishes

Culinary

Unlike more delicate varieties, Long Leaf lettuce can be gently braised, wilted, or added to soups without completely falling apart. Popular in Asian stir-fries and Mediterranean cuisine. [source]

💊

Nutritional & Health Benefits

Medicinal

Rich in vitamins K, A, and C, plus folate and dietary fiber. Contains lactucarium, a mild sedative compound traditionally used in herbal medicine. Low in calories and cholesterol-free. [source]

🏠

Food Storage & Preservation

Household

Whole heads can be stored in the refrigerator for 2-3 weeks. Outer damaged leaves can be removed, and heads can be washed and spun dry before storage to extend shelf life. [source]

🦋

Pollinators & Garden Ecology

Wildlife

When allowed to bolt and flower, Long Leaf lettuce produces delicate yellow flowers that attract bees, butterflies, and beneficial insects. Letting a few plants go to seed supports pollinator habitat. [source]

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

Harvest Tips

Begin harvesting outer leaves when plant is 6-8 inches tall (cut-and-come-again method), or wait 50-75 days and harvest entire head by cutting 1 inch above soil level. For whole heads, cut in early morning when leaves are crisp and full of moisture. Harvest before temperatures consistently exceed 75°F, as heat causes bolting and bitterness. Refrigerate immediately in plastic bags to maintain crispness.

Fun Facts

  • 🌱 Long Leaf lettuce is also called 'Romaine' because it is believed to have originated in ancient Rome. The name 'cos' comes from the Greek island of Kos, where it was cultivated.
  • 🌱 Long Leaf lettuce contains a milky sap (lactucarium) that has been used in herbal medicine for centuries as a mild sedative, earning it the nickname 'lettuce opium' in some historical texts.
  • 🌱 The crispy texture of Long Leaf lettuce is due to its high water content (95%) and the waxy cuticle on its leaves. Harvesting in the cool morning when cells are fully hydrated maximizes crispness.

Gardening Terms

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

Bolt Compost Full Sun Partial Shade Succession Planting True Leaves
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