A variety of lettuce cultivars are appropriate for container gardening. The easiest type to grow is leaf lettuce, although other types for home gardening include butterhead, crisphead and romaine. Lettuce is a cool-season vegetable, and many varieties will not tolerate warm weather. One benefit of growing lettuce in pots is that you can move the container into an area with cooler temperatures, if necessary. Starting lettuce from seed means it will be ready for harvest in 45 to 60 days.
Select a container. Choose a pot with good drainage and at least 6 inches of space for the lettuce root system.
Select your soil and put it in your pot. Lettuce needs well-drained soil, so add an inch of coarse gravel in the bottom for best results. Then fill the container with a synthetic soil for vegetable container gardening, available at nurseries and garden centres. Allow an inch of room at the top.
Moisten the soil, then press the seeds 1/4 inch below the surface and space them 1/2 inch apart. Mist the seeds regularly until they are established. Place the container in a warm, well-lit area.
Fertilise the seedlings after they emerge. Do not use fertiliser during the germination stages. Use a complete fertiliser that can be poured over the plants.
Harvest the lettuce when plants reach 4 or 5 inches in height. Trim the lettuce with garden scissors to 1 inch above the soil. Continue to harvest every two weeks.
Plant multiple containers of lettuce in successive weeks for optimal crop yield. You can harvest one container one week, and the second container the next week, and so on.