Growing your own lettuce in containers is not difficult and allows you to grow lettuce in the winter even if you do not have a heated greenhouse. There are plenty of dwarf varieties of lettuce available that are good for growing in containers.
The large hearted cabbage varieties are not suitable as they require a lot of space, so either choose one of the dwarf varieties of one of the cos or American loose-leaf varieties. A variety of cabbage lettuce called “Tom Thumb” which was specially bred for small gardens only needs 15cm of space when mature and will grow well in a 20cm pot.
Which ever container you use (tubs, pots etc) fill with good quality compost and sow the seed about 7.5cm (3”) apart and cover with a fine layer of compost. If room allows you can use several containers for successional sowings. Once the seedlings are about 5cm (2”) tall thin out to 15cm (6”) for loose-leaf varieties and 20 cm (8”) for cos varieties. If you are using individual pots sow three seed in each pots and then thin to the strongest.
The containers must be kept in a warm sunny position and as the lettuce plants are 90% water and hence need a lot of water to grow you must never let the soil dry out.
As soon as the lettuce are ready harvest by cutting for cos and cabbage varieties or by pulling the outer leaves of the loose-leaf varieties. Once one plant is cut you can re-sow in the same pot for a second harvest.