The latest planting time of lettuce

Lettuce is an annual or biennial herbaceous crop of the genus Asteraceae lettuce. It is native to the Euro-Mediterranean coast and domesticated from wild species. The ancient Greeks and Romans first ate it, and it has a long history of being introduced into China. There are more cultivation in the southeast coast, especially in the suburbs of big cities and in Guangdong and Guangzhou. Let's take a look at when lettuce is planted.

Growth habits of lettuce

Lettuce likes cold environment and is neither cold-resistant nor heat-resistant. The suitable temperature for growth is 15-20 ℃, and the growth period is 90-100 days. The seeds were tolerant to low temperature and could germinate at 4 ℃. The optimum temperature for germination was 18-22 ℃, and almost no germination was found when the temperature was higher than 30 ℃. During the growth period, I like the cool climate, and 15-20 ℃ is the most suitable for growth, with high yield and good quality. The growth is poor when the temperature is higher than 25 ℃, but the cold tolerance is also strong. 0 ℃ or even short-term sub-zero low temperature does not hinder the growth. The root system is developed, the leaves are waxy, and the drought tolerance is quite strong, but cultivated on fertile and humid soil, the yield is high, the quality is good, and the soil pH value is 5.8-6.6.

Sowing time of lettuce

Lettuce likes the cold climate, so the sowing time is usually in spring and autumn. Spring usually begins to sow from February to April, and can be harvested from May to June, while autumn sowing can start at the end of August and can be harvested from September to October. Because the characteristics of different varieties of lettuce are different, when choosing the sowing time, you should first know the description of the seeds of lettuce you buy. Then sow seeds in combination with the above sowing time. Spring and summer are suitable for sowing loose leaf lettuce (such as cream lettuce, colored leaf lettuce), more heat-resistant, autumn and winter are suitable for sowing heading lettuce (also known as western lettuce), not heat-resistant.

Sowing method of lettuce

1. Sowing: lettuce seeds are too small and light, need to be accompanied by fine sand, mix evenly in a container, and then sprinkle on the soil, covering 0.5 cm, a thin layer, 15-20 degrees, about 3-5 days, it is difficult to germinate when the temperature is higher than 25 degrees. When planting in summer, soak the seeds for 1 night, then wrap them in wet gauze, put them in the freezer (about 5 degrees), and sow more than half of the seeds when they are white.

2, seedling stage: lettuce seedling stage to keep the soil moist, can not dry, keep the soil permeable, 2-3 true leaves time seedlings, plant spacing 5-8 cm.

3. Transplanting: when the lettuce seedlings grow to 5 or 6 true leaves, the seedlings should be watered thoroughly before moving, and the soil on the roots should be moved to a large basin. The distance of loose leaf lettuce plant is 15 cm, and the result is 30 cm. Water thoroughly, put the seedlings in a cool place in summer, stand firm in a week or so, and shine in the normal sun.

4. Fertilization: lettuce seedlings were fertilized once a week after transplanting (nitrogen fertilizer was the best mature organic fertilizer), organic fertilizer or total nitrogen, phosphorus and potassium compound fertilizer was applied again 2 weeks and 4 weeks after transplanting, and fertilization was stopped 2 weeks before harvest.

5. Watering: lettuce is watered early or late at high temperature, a small amount of water is better, but avoid waterlogging, the early growth stage is suitable for water control and keep moist.