If there is frost, will Caicai freeze to death?

Lettuce won't freeze to death when it is frosted.

Lettuce likes cold environment, neither cold nor heat. The suitable growth temperature is 15℃ to 20℃, and the growth period is 90 days to 100 days. Seeds can tolerate low temperature and germinate at 4℃. The optimum germination temperature is 18 ~ 22℃, and almost no germination occurs above 30℃. During the plant growth period, it likes cool climate, and it is most suitable to grow at 15 ~ 20℃, with high yield and excellent quality; When the temperature continues to be higher than 25℃, the growth is poor, the leaves are coarse and old, and the leaves are slightly bitter. However, the cold tolerance is also quite strong, and even the short-term sub-zero temperature of 0℃ will not cause great obstacles to growth.

Cultivation techniques of lettuce

Lettuce likes cold environment, neither cold nor heat. The suitable growth temperature is 15℃ to 20℃, and the growth period is 90 days to 100 days. Seeds can tolerate low temperature and germinate at 4℃. The optimum germination temperature is 18 ~ 22℃, and almost no germination occurs above 30℃.

During the plant growth period, it likes cold climate, and it is most suitable to grow at 15 ~ 20℃, with high yield and excellent quality; When the temperature continues to be higher than 25℃, the growth is poor, the leaves are coarse and old, and the leaves are slightly bitter. However, the cold tolerance is also quite strong, and even the short-term sub-zero temperature of 0℃ will not cause great obstacles to growth.

Lettuce has developed root system, waxy leaves and strong drought tolerance, but it has high yield and good quality when cultivated in fertile and humid soil.

The suitable pH value of soil is 5.8 to 6.6.

Selecting and sowing improved varieties

Appropriate varieties should be selected according to needs, such as glass lettuce, head lettuce, mosaic lettuce and Hu Da 659.

Prepare seedbed

Lettuce seedlings should be planted in sandy loam with good water and fertilizer conservation ability. Soil preparation for seedbed: 10 square meter seedbed is made of decomposed organic fertilizer 10 kg, 0.3 kg of ammonium sulfate, 0.5 kg of calcium superphosphate and 0.2 kg of potassium sulfate, which are fully and evenly mixed, leveled and raked, filled with water, and sowed after seepage.

Sowing and seedling raising

In order to make the sowing uniform, a small amount of fine sand can be mixed into the seeds when sowing, and 0.3-0.5 cm thick moist soil should be covered after sowing, and plastic film should be covered to keep moisture. The sowing amount per mu is 30-50g. When the seedlings begin to be unearthed, the plastic film at the border should be uncovered in time to prevent the seedlings from growing in vain. The temperature of seedbed should be controlled at 65438 08℃ ~ 20℃ during the day and 65438 02℃ ~ 65438 04℃ at night. Pay attention to ventilation, and keep out the sun when the strong light shines. When the seedlings grow to 2-3 real leaves, divide the seedlings according to the row spacing of 6-8 cm. When the seedlings grow to 4-5 true leaves, they can be planted. Generally, there is no shortage of water and no watering at seedling stage. To prevent seedling diseases, 1 to 600 times of 75% chlorothalonil solution can be sprayed twice.

Scientific fertilization

Lettuce needs clay loam with rich organic matter and strong water and fertilizer retention ability. Lettuce is slightly acidic, and the suitable soil pH is 5 to 7. Every 1000 kg of lettuce should absorb 2.5 kg of nitrogen, 0.2 kg of phosphorus/kloc-0 and 4.5 kg of potassium. Among them, lettuce needs more potassium. Nitrogen, phosphorus and potassium fertilizer need to be used together during the growth period. The field where lettuce is planted should be intensively cultivated. Before planting, sufficient base fertilizer should be applied, and 3000 ~ 3500 kg of decomposed farmyard manure should be applied per mu. After application, it should be ploughed deeply, watered with sole water and dried as a border.

Careful planting

Irrigate the seedbed one day before planting to make the seedlings moist, and borrow as much soil as possible the next day to reduce root damage. When planting, first ditch the border with a depth of 4-6 cm, and plant 3 rows with a depth of 70 cm. After ditching, apply 25 kilograms of ternary compound fertilizer per mu, and then irrigate. After water seepage, put the seedlings at a spacing of 24 cm, cultivate the soil to seal the ditch, level the border, cover it with plastic film, and lead the seedlings out of the film.

Post-planting management

Lettuce likes humidity, and it needs sufficient water supply throughout the growing period. After planting for 5 ~ 7 days, irrigate with slow seedling water 1 time. After watering the seedlings slowly, turn over the uncovered plots twice and loosen the soil to weed. After watering for 3 ~ 4 times, apply nitrogen and phosphorus fertilizer in stages, and apply15 ~ 20kg per mu. Stop watering before harvesting to facilitate storage and transportation.