Lettuce

Growing Conditions

Lettuce prefers temperatures between 60°F and 70°F. It germinates well in cool soil and tolerates light frost. Heat above 75°F triggers bolting — the plant sends up a flower stalk, leaves become bitter, and production ends. Light shade from taller crops or a 30% shade cloth extends the harvest window by several weeks in warm weather.

Cold climates: Direct sow as soon as soil can be worked in spring — 4–6 weeks before last frost. For fall, sow 6–8 weeks before first frost for harvest before hard freezes arrive.

Warm climates: Lettuce is a cool-season-only crop. Focus on fall, winter, and early spring plantings. In mild-winter climates, lettuce can produce year-round with minimal shade.

Sowing & Planting

Surface sow or barely cover seeds — lettuce needs light to germinate. Sow thinly in rows or broadcast and rake lightly. Thin to 6 inches for leaf types, 10–12 inches for heading types. Alternatively, start transplants indoors 3–4 weeks before setting out.

Succession sow every 2–3 weeks to maintain continuous production. A small sowing every few weeks provides steady harvest without overwhelming gluts.

Care & Maintenance

Keep soil consistently moist — lettuce has shallow roots and dries out quickly. Mulch helps retain moisture. Lettuce is a light feeder; average soil is sufficient. Avoid high-nitrogen fertilizers that push soft, pest-prone growth.

Common Problems

Bolting is the main challenge. Choose heat-tolerant or slow-bolt varieties for spring plantings, and time fall plantings carefully. Tip burn — brown leaf edges on inner leaves — is caused by calcium deficiency or poor air circulation, not a pest. Aphids can be heavy; knock off with water or treat with insecticidal soap. Slugs damage seedlings and young leaves — use traps or diatomaceous earth around beds.

Harvest

For loose-leaf types, cut outer leaves once plants reach 4–6 inches tall, leaving the growing center intact. Plants will regrow 2–4 times before declining. For heading types, harvest the whole head when firm and full. Harvest in the morning when leaves are crisp and cool.

Varieties

Loose-leaf varieties (Black Seeded Simpson, Oak Leaf, Red Sails) are the most productive for continuous harvest and the easiest to grow. Butterhead/Bibb types (Buttercrunch, Boston) form loose, tender heads with excellent flavor. Romaine types are upright and heat-tolerant compared to other lettuces. Iceberg types require the most consistent cool temperatures to head properly and are the most challenging for home growers.

Variety selection for spring should prioritize slow-bolt or heat-tolerant labeling. For fall, almost any variety performs well.