Lettuce

Lettuce is an annual leaf vegetable in the family Asteraceae, cultivated in an enormous range of forms — loose-leaf, butterhead, cos, crisphead and cut-and-come-again bowl types. Its milky sap gives the genus its Latin name. Varieties range from pale green to deep burgundy-red, offering mild, tender flavour with minimal bitterness. It thrives in cool conditions and bolts rapidly once temperatures climb or days lengthen significantly.

Growing

Sow seed at 0.5 cm depth — lettuce is a light-germinator and must not be buried deeper. For indoor starts, sow into small cell trays 3–5 weeks before transplanting out, keeping the propagation space below 18 °C; germination stalls or fails above that threshold. Minimum soil temperature for germination is 5 °C. Transplant seedlings outdoors once nights remain reliably above 2 °C, hardening off gradually. For direct sowing, begin as soon as the soil is workable at 5 °C or above. Space plants 15–25 cm apart in rows 30–50 cm apart; closer spacing suits cut-and-come-again leaf harvesting, wider spacing for full heads. Sow in successive small batches to extend the harvest continuously.

Care

Keep soil evenly and consistently moist — lettuce is shallow-rooted and wilts quickly under drought stress. Water with the coldest water available; cold irrigation reduces soil temperature and lowers the risk of premature bolting during warm spells. Apply a balanced liquid feed every two weeks once plants are established. Mulch around plants to retain moisture and suppress weeds. Remove any flower stalks immediately as bolting makes leaves bitter. In hot conditions provide afternoon shade with netting or companion tall crops.

Harvest

For cut-and-come-again types, begin harvesting individual outer leaves as soon as they reach usable size, leaving the growing centre intact; the plant will continue producing new leaves. For headed varieties, harvest when the head feels firm and dense under gentle pressure, before any central stem elongation is visible. Cos and butterhead types are ready when the inner leaves are tightly packed. Cut the whole head at the base with a sharp knife. Harvest in the cooler part of the day to maximise crispness and extend shelf life.

In the kitchen

Use fresh lettuce raw as the base for green salads, layered into sandwiches and wraps, or as cups for minced fillings. Cos varieties hold up well briefly on a hot grill or wok. Baby leaves work well in mixed salad bowls alongside stronger-flavoured greens. Stems of celtuce types are sliced raw or stir-fried. Heartier outer leaves can be braised or added to soups where they soften without dissolving.

Storing

Whole heads keep for up to 7–10 days in the refrigerator at 1–4 °C, wrapped loosely in a damp cloth or sealed in a perforated bag away from ethylene-producing fruits. Separated leaves keep 3–5 days in a sealed container lined with dry paper towel. Do not freeze lettuce — the high water content results in a limp, unusable texture on thawing. For a continuous supply, stagger sowings rather than storing large quantities.