Lettuce is a vegetable that prefers growing in soil with temperatures between 40 and 60 degrees. If the temperature rises above 60 degrees, lettuce plants will “bolt.” Bolting is when a lettuce plant sends up a tall flower before going to seed, creating bitter leaves. Plant lettuce seeds as early as you can work the soil because lettuce tolerates frost easily.
Prepare a sunny garden area early in the spring, as much as four weeks prior to the last anticipated spring frost. Work the soil with the spade, making it extremely fine. Lettuce seeds are tiny and may have trouble breaking through large chunks of soil. Spread a 2-inch layer of compost over the soil and work it in with the spade. Rake the surface of the soil smooth.
Sow the seeds by scattering them. It is difficult to plant lettuce seeds in rows, due to their size. Cover the lettuce seeds with 1/4-inch of soil. Water the lettuce seeds lightly after planting.
Water every two or three days so the seeds, and later the seedlings, do not dry out. Give the seedlings at least 1 inch of water per week.
Thin lettuce seedlings when they are approximately 2 inches tall. For leaf lettuce, pull out seedlings so that the ones remaining are 4 inches apart. For head lettuce, thin seedlings to 8 inches apart.
Harvest leaf lettuce during the morning hours when leaves are between 2 and 6 inches long. Use the scissors to cut the leaves approximately 1 inch above the soil level. Harvest head lettuce when the heads are firm as you press on them. Pull the entire lettuce head and roots out of the soil and slice the roots from the lettuce head with the garden shears.