Lettuce is an ideal addition to any garden, and can be grown outside, in a greenhouse or on a sunny windowsill indoors. Looseleaf, butterhead and romaine are the easiest and most nutritious lettuces to grow. Lettuce thrives in cooler temperatures, ideally between 50 and 70 degrees Fahrenheit.
Fill a seed tray with nutrient-rich soil specific for growing vegetables until it is almost to the top of the tray's rim.
Sprinkle the lettuce seeds on top of the soil, trying not to layer them over each other.
Sprinkle another layer of soil on top, patting it down slightly with your fingers. The point is to not bury them, but to keep them protected between two light fluffy layers of soil. Use a spray bottle to moisten the soil and the seeds. You will probably see germination in about a week if the soil temperature is around 50 degrees.
Put the seed trays in a sunny location, indoors or outdoors, for at least six hours of direct sunlight per day.
Spray the soil daily with water while the plants germinate and begin to grow. Thin the seedlings to allow about 6 inches between each lettuce plant.