Do you need topdressing to grow lettuce? What fertilizer is the best?

Lettuce is an annual or biennial herb in Compositae, which is native to the Mediterranean region. It has a cold climate and is resistant to cold and heat. The optimum growth temperature is between 15-20 degrees, and the root system is developed, which makes the fertile slightly acidic soil loose. From the growth habit of lettuce, it can be seen that lettuce is not the current 10 temperature condition, but it is not impossible to grow lettuce now. After years of planting and continuous planting, there are many varieties of lettuce on the market now. However, some problems should be paid attention to when choosing lettuce varieties planted in summer. Lettuce varieties have good heat resistance first, and then need high quality, high yield, disease resistance and easy topdressing. At present, the varieties of lettuce with good planting effect in summer include summer green skirt, American raw lettuce and Italian lettuce. When choosing, growers should choose according to the situation of planting areas.

Lettuce seeds can germinate at low temperature. The optimum germination temperature is 18 ~ 22℃. It is precisely because of this characteristic that lettuce seeds are difficult to germinate when the temperature exceeds 30 degrees. Lettuce planted in summer must germinate at low temperature to ensure germination rate and save seedling time. Cui Ya's method is to soak the seeds in clear water for 3-4 hours, so that the seeds can be fully absorbed, then wrap them in moist and clean gauze, and put them in the refrigerator at about 10 degree to accelerate germination. Generally, the seeds of lettuce will be exposed for sowing in about 24-48 hours.

The sowing time of summer lettuce is usually from the beginning of June to the end of July. Before sowing, the land planted should be fertile. Generally, the corroded organic fertilizer is 2000 ~ 3000 kg per mu, and the phosphoric acid is about 15 kg. Generally, the sowing method is by hand. The germinated seeds are evenly spread into the ditch, covered with thin soil, and the soil is kept moist. Generally, it germinates in 3-4 days. In order to produce high-yield lettuce and get rid of malnutrition and daily management, Zhu Heng used rotten farmyard manure and later harvested ether. I thought lettuce should look good after spending a lot of fertilizer and money, but it didn't take long for lettuce and rape leaves to turn yellow. He asked many experts that potassium fertilizer was not enough, and finally lettuce was grown without potassium supplementation.

Nitrogen fertilizer is the most indispensable for the growth of leafy vegetables, and potassium fertilizer and nitrogen fertilizer play an equally important role in the high yield of lettuce. Applying potassium fertilizer on the basis of nitrogen fertilizer can obviously increase the yield. Moreover, the application of potassium fertilizer can reduce the consumption of organic matter and prolong the storage time. So, how to fertilize this lettuce and leafy vegetables reasonably? The following methods are very suitable for green planting, and can be used in small vegetable gardens, plastic greenhouses and plastic greenhouses.