How to grow lettuce: most gardeners grow lettuce from seed directly sown outside in the ground or in pots. Lettuce grows very quickly so transplanting is not necessary.
Sow lettuce seeds 0.4 inches (1.1 cm) deep, 1.5 inches (3.8 cm) apart, and rows 15.2 inches (38.5 cm) apart. Optimal soil temperature for germination is between 55.2°F (12.9°C) and 70.6°F (21.4°C). Seeds will germinate in about 6-13 days.
Lettuce requires only 40-55 days to be ready for harvest from seed, depending on the lettuce variety selected and the weather during the growing season. Do no wait until lettuce plant bolts to fully mature plant, bearing flowers, because the sweet taste becomes bitter.
Lettuce plants will bolt in high temperatures of 90°F (32.2°C) and long exposure to sun. To avoid this you may want to plant lettuce seeds in a more shaded area reducing exposure to sun.
Optimal day air temperature for growing lettuce is between 57°F (13.9°C) and 65.6°F (18.7°C). Optimal night temperatures are between 49.7°F (9.8°C) and 56.6°F (13.7°C). Lettuce can endure air temperatures as low as 32°F (0°C) during the night and up to 70°F (21.1°C) during the day.
Soil temperature during lettuce growth should be between 46°F (7.8°C) and 67.7°F (19.8°C) in optimal conditions, but can withstand soil temperatures as low as 40°F (4.4°C).
Required soil pH for lettuce growth is 6.0-7.2 but the optimal pH is 6.2-6.5.
Optimal sunlight for Lettuce is 6 hours per day. Lettuce should be watered between 1.0-1.5 inches (2.5-3.8 cm) of water per week, adjusting for weather conditions and type of soil accordingly.
Lettuce spacing: When planting lettuce seeds directly into the ground sow seeds 0.4 inches (1.1 cm) deep spaced 1.5 inches (3.8 cm) apart with rows spaced 15.2 inches (38.5 cm) apart.
How to grow lettuce in your garden: one of the best things about growing lettuce is that you can harvest in a relatively short period of time. To ensure that you have lettuce throughout the growing season we recommend you plant new lettuce seeds every 1-2 weeks. As you are harvesting the first batch, your next batch is getting ready.
Harvest outer leaves as soon as their big enough to eat. We recommend using your hands to snap off the leaves rather than tools to cut the leaves. The best thing about lettuce is that after you harvest it will continue to grow and produce leaves so long as proper temperatures exist.