Lettuce, the universal salad ingredient has undergone a revolution since the mid 1990’s. Crisp or butterhead, hearted or loose leaf, frilly or plain, there is a lettuce to fit every taste, season, and garden. Many organic cultivars are available. This crop is divided into four types, butterheads, crisp heads, romaine, loose leaf or salad bowl.

Butterheads- are soft hearted with a soft almost greasy leaf. These are the most heat and drought tolerant cultivars

Crispheads- crunchy crisp leaves forming solid hearts and are heat tolerant for summer crops. Some cultivars are suitable for winter growing in a unheated greenhouse or hoop house.

Romaine- upright habit with more substantial crisp tasty leaves and a loose heart. Slower to mature than butterhead or crisphead

Loose leaf- are non-hearting, with a diverse range of leaf color and shape. Individual leaves can be picked over many weeks; this crop is slow to bolt. This type of lettuce is suitable for seedling crops.

Ideal Site- Lettuce will tolerate most soils except dry or poorly drained. These plants appreciate light shade in the summer and are suitable for interplanting between rows of brassicas or underneath tripods of runner beans. Usually no soil treatment is needed where soil is regularly improved for vegetable. On poor soil apply a medium-fertility soil improver. The ideal pH range is 6-7. Most cultivars are suitable for container growing.

Seed to Harvest- 4-14 weeks depending cultivar.

Cultivation- Minimum germination temperature for lettuce is 41F (5C).and germination is inhibited in temperatures above 77F (25C)

Sowing under cover- For summer and autumn crops sow in cell pack trays from February to early July although once temperatures warm, it is generally more successful to sow directly outside. For a continuous supply sow in 2 week intervals. Harden off before planting outside.

Sowing outdoors- Sow directly in soil in 3ft(1M) row of each cultivar at 2 week intervals from April or when the ground is warm enough to September. Thin out plants when large enough to handle. Some cultivars particularly the Loose leaf should not be grown during the hottest summer months.
 

Spacing- 6-15in x 8-14in (15-38cm x 20-35cm) for rows and 8-14in (20 x35 cm) for block planting depending the cultivar.

Plant Care- Water until established and during dry periods to prevent lettuce from becoming bitter. Keep greenhouses and hoop houses well ventilated to prevent mildw and otrytis in overwintering crops.

Problems- Aphids, lettuce root aphids, cutworms, downy mildew, gray mold, and bolting (turning to seed) in hot weather.

Harvesting – Hearted lettuce should be cut as soon as they are hearted or the will quickly bolt. Looseleaf lettuce leaves should be picked from the outside of the plant as required. Seedling cutting crops should be harvested when plants are 2in (5cm) tall or about 4 weeks aftersowing. 2-3 subsequent cuts can be made.

Nutrients- Not all lettuce is created equal but most contain vitamin A,B1,B2,B3, B6, C,K, folate, potassium, chromium, phosphorus, molybderum, iron, manganese, calcium, dietary fiber, tryptophan, protein, and omega 3 fatty acid,