What hardiness zones is Lactuca sativa var. longifolia suitable for?

Lactuca sativa var. longifolia encompasses romaine (cos) lettuce types in the Asteraceae 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

Upright, elongated, vase-shaped head with spatulate leaves bearing a thick crisp midrib. Distinguished from crisphead by the elongated shape. Distinguished from butterhead by the crisp crunchy texture.

Appearance

Size & Dimensions

Height8" - 1'

Width/Spread8" - 10"

Reaches mature size in approximately 1 years

Colors

Flower Colors

yellow

Foliage Colors

green

yellow

Bloom Information

Yellow flowers when bolting — later than crisphead.

Detailed Descriptions

Foliage Description

Medium to dark green outer; pale inner

Growing Conditions

Sun Requirements

Full Sun Partial Shade

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

Soil Requirements

pH Range6.0 - 7.0(Neutral)

357912

Soil Types

loam silt

Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

60-75 days

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.