Autumn lettuce is planted in the hot season in summer and early autumn. The temperature is high and seed germination is difficult. Special management should be conducted to cultivate strong seedlings. The optimum temperature for seed germination is 15-18Â°C, and the maximum temperature is 28Â°C, and it needs to see light. Therefore, low-temperature germination is required before the autumn lettuce is sown. Methods are as follows: 1. Hanging well method: Seed is soaked with newly proposed well water (15Â°C or so) or cold water soaked for 5-6 hours, rinsed 2-3 times, remove mucous impurities, remove and leave to dry, and wrap it with a wet cloth bag. Hang 10-30cm above the surface of the well, keep the temperature at 15Â°C, wash with well water once or twice a day, and shoot 3-4 days. 2, cold method: the seeds soaked for 24h, rinsed clean, wrapped in gauze, on the refrigerator or freezer, in the 3-5 Â°C temperature refrigerated 24h, then placed in a cool ventilated place, the seeds germinate slowly. When the buds are white, spread out in a cool, airy place with scattered light, and pay attention to spray, moisturize, and prevent dryness. After 2-3 days, when the germ appears pale green, it can be sown. After germination and sprouting, they are neat and emergent and have strong resistance to stress. 3, sand mixing method: the seeds soaked after 1-2h mixed with wet sand, placed on the air defense or water tank side, keep cool and moist conditions, 3-4d to germination. 4, irrigation cover method: seedbed after baking over the white, the whole leveling fine, spread sowing seeds, which cover a thick layer of straw, and then use bamboo or bricks to suppress the straw. The seedbed soaked in water every day in the evening, and the seeds germinated in 2-3 days. 5, growth regulator germination method: in the 30-40 Â°C high temperature, can also be used 5mg / l of gibberellin ("920"), 5mg / l 6-benzylaminopurine soak about 8h, and then rinse with tap water , you can sow, the germination rate can be increased to about 80%. If 6-benzylaminopurine is mixed with gibberellin 5 mg/l, the effect is better. In the use of 6-benzyl amino purine and gibberellin should be noted that the concentration can not be higher than 7.5mg / l, otherwise it will reduce the germination rate, causing phytotoxicity. After sowing, we must use a shade shed (cloudy sky) or shade nets. We can also plant seeds under the guashes, or mix them with the unearthed cabbage.