Nowadays, there are too many vegetables that are directly planted seedlings, which can better control the quality of seedlings, improve the quality of vegetables, and also save the link of seedlings after sowing, saving a lot of time. Then it is convenient to buy seedlings, whether it is to buy a large number of seedlings or only a few, it is also very convenient to raise seedlings at home. But planting seedlings is not a very simple thing, different vegetables, different stubble seedling planting methods are not the same, some vegetable seedlings are not good to live, and even a large number of dead seedlings will occur, so that farmers have huge losses. 
To produce high-quality lettuce, most of them are transplanted after seedlings1. When to plant seedlings in spring is mainly related to local temperature conditionsWhether it is in the seedling tray, nutrient bowl or seedbed, it will involve the process of seedling replanting, root breaking and regrowth, and the root system leaves the original growth environment and regrows in the new soil environment. If the most suitable environmental conditions can be provided, the seedlings will regrow quickly after planting and there will be no dead seedlings. What kind of temperature is required for the root system to root varies according to the temperature requirements of vegetablesCold-tolerant or cold-loving vegetables such as Chinese cabbage and lettuce, the suitable temperature for root growth is 15 25, and more than 10 can also slowly sprout roots, and the suitable temperature range is relatively wideTemperature-loving nightshade vegetables are not strict with temperature, and seedlings can be planted when they are above 12For melon vegetables with strict temperature requirements, the suitable temperature for root growth is 20 25, and the minimum temperature is above 15 before seedlings can be planted, the survival rate is greatly reduced at lower temperatures. 
When to plant seedlings in spring, it must be different in different places, and the Central Plains region where we are located, except for the cold and cool areas in the high mountains, most of them are(1) Open field: As early as late April, you can plant eggplant fruits and vegetables, and start planting melon vegetables in early May. (2) Plastic arch shed: As early as mid-March, cabbage and nightshade are planted one after another, and melons are planted in early April. (3) Solar greenhouse: The sunken solar greenhouse has a very good thermal insulation effect, the minimum temperature in winter can be above 10, considering the stubble, usually planting spring stubble eggplant fruit vegetables in February, and planting autumn stubble melon vegetables at the end of February. 
Second, how to plant seedlings, how to manage the survival rate of seedlings after plantingIn addition to better survival of vegetable seedlings under suitable temperature conditions, there are also certain requirements for seedling planting technology and post-planting management. (1) Minimize seedling root damageNowadays, the seedling tray is mostly used to protect the roots and raise the seedlings, which has reduced the root damage as much as possible, on the one hand, it reduces the invasion of pathogens into the plants, and on the other hand, it is faster than the complete root system. All kinds of vegetables have their own seedling standards, one of the common points is that the root system has developed to a certain extent, and the intuitive performance is that the root system is enough to be coiled in the hole, and the root system can be completely taken out from the seedling tray. If the seedlings are not particularly arid and the substrate soil is not very loose, it does not affect the seedlings, and the seedlings can be watered thoroughly after planting. It should be noted that if you raise seedlings by yourself, carry out drought and cold resistance exercises before planting, so that they can adapt to the environmental conditions of low temperature, strong wind and sun exposure in the field than the seedling site. 
(2) The planted plots should be finely preparedThe root system needs a loose and breathable soil environment, the soil is too hard, there are too many big leaves, and the texture is too sticky, which will affect the growth of the root system, and the roots may be very slow, or the seedlings may be sunburned. In addition, there are many underground pests and germs in the soil, and if the seedlings are not controlled, the young stems, leaves, and roots will be eaten and the seedlings will die. Therefore, it is best to add insecticides and fungicides, such as phosphine, chlorothalonil, carbendazim, etc., to carry out soil disinfection. You can also plant seedlings while adding some pesticides to the soil near the root system, if the seedlings are still found to be harmful insects or cataplexy, standing withering, stem base rot occurs, you need to buy water-soluble agents, with drip irrigation applied to the root system, insecticide, sterilization, prevention and control of pests and diseases. 
(3) After planting, if the seedlings can be given a high temperature and high humidity environment, they will survive faster and betterAfter the seedlings are planted, the root absorption capacity is weak but the plant will still lose water through transpiration, in order to better balance this short process, if the shed is cultivated, the shed can be closed for a day or two after planting, the high humidity environment can reduce the loss of transpiration water, and the high temperature can promote the roots, if the temperature is not particularly high, do not need to open the air outlet, and the heart leaf growth is considered to be alive after a day or two. For open field planting, if possible, a simple small arch shed can be built to promote the survival of seedlings.