Lettuce is a hardy vegetable and can be planted as early as the soil can be worked. It is a cool-weather crop and does best when temperatures are in the 60°F to 65°F range. I sow new seeds about every two weeks to keep a fresh supply of lettuce on hand, and stop seeding when daytime temperatures reach 70°F to 75°F. Cover the seeds with a fine layer (1/8” max.) of fine soil, then firm lightly. You can either seed in a bed or in rows. Keep moist. Lettuce can be started in flats, or Jiffy pellets, and transplanted into containers or the garden.
Once the plants are ready to harvest you should cut the leaves, rather than pulling the plant out, to encourage re-growth. Cutting the leaves about 2" from the soil surface seems to give the best results. Some varieties taste best on the first harvest, others the second or third. Don't worry about harvesting "baby" leaves- they will grow back.
Lettuce does very well in containers. A sandy, rich mix tend to give us the best results- 25% sand, 25% perlite, 50% quality compost material. Make sure you have plenty of holes in the bottom of the container.