The relative height of leek on the ground is less than 30 cm, and this kind of leek can be used as a product leek. If some leeks on the ground are only a dozen centimeters, and the upward trend is not very good, there is no commodity value. The mentioned temperature is actually a necessary condition for the growth and development of leeks. After the leek turns green, the temperature continues to rise. Generally, it takes about 35 days from turning green to harvesting. The lowest temperature is seven or eight degrees, and the continuous high temperature is about 20 degrees. At this time, leek has also grown into the market demand of product leek, and the first knife can be harvested.
Generally speaking, because of the long growth and development time, the leaves of the first-cut leek are wider and thicker than those of ordinary leeks, and they look stronger. The roots of the first leek are generally red or purple, and the later leeks are generally white because of their short growth and development time. General specification for planting the first leek in the open field. Chinese chive farmers generally do it according to plant height or days of growth and development. When the plant height is on time, when the leek plant is 35cm and the single leaf is 5~6, it can be harvested.
When the number of days is taken as the standard, the seeds can be gradually harvested from the germination period of leek plants to the growth and development of about 30-35 days. Sometimes it rains continuously in spring. In this case, even if cultivated in the open field in Tomb-Sweeping Day, Chinese chives will be very short, not reaching the relative height of 18cm. However, due to the pursuit of perfection and high price, some businessmen will cut and sell leeks that are not as strong as 15cm.