Climate and Soil
Lettuce requires cool environment. The average mean temperature for growth and better taste is 13-16'C. High temperature promotes seed stalk and causes bitter taste of leaves. It performs well in sandy loam and silt loam soils.
Punjab Lettuce-I (1991) : Its leaves are light green, shining and crispy. It is a non-heading type and bears loose leaves. It takes 45 days from sowing to first harvest of fully developed leaves and yield of green leaves is 35 q/acre. Harvesting of green leaves is possible from November to March.
Sowing Time and Seed Rate : Sow the seed on 15-20 cm.raised nursery beds from mid September to mid November. Transplant 4-6 weeks old seedlings and irrigate at a weekly interval. To raise seedlings for an acre, sow 400 g seed in 2 marla nursery beds.
Spacing : Keep the spacing between seedlings 30 cm. and rows 45 cm.
Manures and Fertilizers
Apply 15 tonnes of FYM,25 kg N (55kg Urea) and 12 kg P2O5(75 kg of Single Superphosphate) per acre. Apply whole of superphosphate and 18 kg urea before transplanting and remaining 37 kg urea after six weeks.
Irrigation : First irrigation should be given immediately after transplanting. Subsequent irrigation should be given at an interval of 5-6 days on light soils but 8 to 10 days on heavy soils.
Harvest fully developed and tender leaves once a week regularly.Stop taking cuttings by the end of March or beginning of April when the plants attain milky stage. Bolting starts in the first week of April.Harvest seed crop in the middle of May. Seed yield per acre is 50 kg.
Lettuce is strictly self pollinated crop and require about 10 meter isolation to avoid mechanical mixture. Seed stalks should be harvested when seed is fully mature on the plants otherwise germination is affected.