Lactuca sativa var. longifolia
romaine lettuce
Overview
Lactuca sativa var. longifolia spp. encompasses romaine (cos) lettuce types in the Asteraceae spp. family. Plants grow 8–12 inches (20–30 cm) tall in an upright, elongated, vase-shaped head. Leaves are spatulate with a thick, crisp midrib providing the characteristic crunch. More heat-tolerant than crisphead — withstands 5–10°F (3–6°C) higher temperatures before bolting. Days to maturity: 60–75 from direct sow. Highest nutritional density of common lettuce types — approximately 10× the vitamin A of iceberg. In PNW, sow March–May and August–September. The base for Caesar salad — sturdy leaves hold thick dressings without wilting.
Native Range
Lactuca sativa is derived from L. serriola, native to the Mediterranean. Romaine types grown since antiquity — 'cos' references the Greek island of Kos.Suggested Uses
Caesar salad base. Grilled romaine halves. Fresh in salads, wraps. Higher nutritional density than crisphead — recommended for health-conscious consumers.How to Identify
Appearance
Growing Conditions
Sun Requirements
Requires 4-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Direct sow 0.25 inch deep, thin to 8–10 inches. Full sun to partial shade, moist soil, pH 6.0–7.0. Water 1 inch per week. More heat-tolerant than crisphead.Pruning
No pruning. Harvest whole head or outer leaves. Leave 1-inch stump for regrowth.Container Growing
✓ Suitable for container growing
Minimum container size: 3 gallons