Late summer sown lettuce can be harvested within 6-8 weeks, so planting in the months of August and September will result in a late autumn crop. Planting during these months, which can still be pleasantly warm, will also encourage fast and effective germination.
Lettuce can be grown on windowsills or in an unheated greenhouse, providing it receives six to eight hours of light per day, and is sown in moist, well-draining soil. Sow into module trays filled with seed compost. Sit the module tray in a shallow tray of water to soak until the surface feels damp then remove. Lettuce seeds germinate at temperatures below 20℃, so do not provide too much heat. By the time the seedings are ready to plant out you will have gaps left by harvested vegetables to fill.
When growing outdoors it is essential to plant lettuce in a location where it will be protected from any early frost damage, so a sunny location where any frozen ground will thaw out quickly is ideal. Sow lettuce seeds in rows spaced 20-30cm (8-12in) apart and water well. You may want to use a cloche to protect them from harsh weather.
Lettuce can be grown and harvested during even the coldest months, providing you know when to plant it, and which types of lettuce are most hardy.
Lamb’s Lettuce has distinctive dark green leaves in the shape of a lamb’s tongue which have a mild, nutty flavour. Sometimes known as Corn Salad, Lamb's Lettuce has long spoon-shaped, dark leaves. This type of lettuce will improve soil fertility when grown in between other plants.
Winter Purslane is one of the hardiest lettuces for withstanding colder temperatures, so much so that it has earned the nickname ‘Miner’s lettuce’. Native to the North American mountains, Winter Purslane grows to a height of around 30cm (1ft) and the leaves take on the shape of a rosette. It grows well in plant pots and flower beds and can be added to salads for a tangy, refreshing taste.
Winter Gem is a mini Cos type lettuce, suitable for growing over winter if protected from frost.