How to Grow Lettuce

A cool-season crop that hates summer

Lettuce prefers temperatures below 75°F and tastes best when plants grow rapidly and mature before the heat of summer arrives. Above about 80°F germination itself drops off, and high temperatures reduce quality and bring on bitter flavors. Everything about growing lettuce well is about beating the heat.

Sow seed a quarter to a half inch deep, 2 to 3 weeks before the last frost, in full sun and fertile, well-drained soil; seeds germinate best at 55 to 65°F. Transplants need about 5 to 6 weeks to reach planting size.

The when-to-plant-lettuce calculator localizes the spring and fall windows to your frost dates, and how-much-sun-does-lettuce-need covers the light question on its own.

Leaf versus head, and succession sowing

Loose-leaf types (like Red Sails, Oakleaf, and Salad Bowl) are the fast, forgiving option — you pick outer leaves and keep going. Head types (crisphead or iceberg, butterhead, and cos/romaine) take longer and need more room and cooler weather to form tight heads.

Space head lettuce 8 to 12 inches apart in rows 12 to 18 inches apart. The lettuce-plant-spacing calculator gives the layout on its own, and lettuce-in-containers covers pots.

Because a single planting bolts as soon as it gets hot, sow a fresh short row every couple of weeks. Succession is what turns lettuce from one flush into a steady supply through spring and again in fall.

Water, feeding, and harvest

Supply 1 to 2 inches of water per week, ideally by drip, and keep it steady — fluctuating moisture causes tough leaves and off-flavors. The how-often-to-water-lettuce calculator gives the watering readout on its own.

Side-dress a quarter cup of a nitrogen fertilizer (21-0-0) per 10 feet of row about 4 weeks after transplanting; the best-fertilizer-for-lettuce calculator covers feeding.

Harvest leaf lettuce by picking before the seed stalk forms, and crispheads when the heads are firm. If the crop turns bitter, that is the heat talking — the why-is-my-lettuce-bitter diagnostic and lettuce-tipburn page cover those problems, and when-to-harvest-lettuce gives the timing.

Sources

Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.

• Utah State University Extension — Lettuce in the Garden — Lettuce is a cool-season crop preferring temperatures below 75°F, needing full sun and fertile, well-drained soil; plant seeds 1/4-1/2 inch deep 2-3 weeks before the last frost, germinating best at 55-65°F with temperatures above 80°F reducing germination; head lettuce spaced 8-12 inches between plants and 12-18 inches between rows; transplants take 5-6 weeks to reach planting size; lettuce tastes best when plants grow rapidly and mature before summer heat, and high temperatures reduce quality and cause bitter flavors; supply 1-2 inches of water per week and fluctuating moisture causes tough leaves and off-flavors; apply 1/4 cup of 21-0-0 per 10 feet of row 4 weeks after transplanting; harvest leaf lettuce before the seed stalk forms and crispheads when heads firm; leaf types include Red Sails, Oakleaf, Salad Bowl and head types include Crisphead/Iceberg, Butterhead, and Cos/Romaine.

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