The flower of walnut seedling is wind-pollinated. The distance of pollen dissemination is related to wind speed and terrain, etc. Within a certain distance, the amount of pollen dispersal increases with the increase of wind speed, but decreases with the increase of distance. According to research reports, the best pollination distance should be within 100 meters from the pollination tree. Beyond 300 meters, almost no pollination can occur, at this time artificial pollination is needed. The life span of pollen under natural conditions is only about 5 days. According to measurements, the viability of freshly dispersed pollen is as high as 90%, and it drops to 70% after one day. Under indoor conditions, all pollen loses activity after 6 days, even under refrigerated conditions in the refrigerator, 12 days after collection, the viability also drops below 20%. During the day, the best time for pollinating female flowers is between 9-10 am. The effect is greatly related to weather conditions and flowering conditions. Years of experience have proven that those with short female flower periods and neat blooming have higher fruit setting rates; otherwise, they are low. According to surveys, those with female flower periods of 5-7 days have high fruit setting rates of 80-90%, those of 8-11 days have fruit setting rates below 70%, and those of 12 days have only a 36.9% fruit setting rate. If the flowers encounter low temperature and rainy weather during the flowering period, it will significantly affect normal pollination and fertilization activities, reducing the fruit setting rate. New walnut orchards need to be equipped with pollinating varieties, with a ratio of 3:1 or 4:1 to the main cultivated variety, or they can be planted in alternate rows or alternate plants. Generally, pits can be dug in a range of 50-80 cm, depending on the soil quality. When digging the pit, place the upper surface on the left and the lower surface on the right, mix topsoil with fertilizer, such as fermented chicken manure, and avoid using chemical fertilizers (which easily burn roots). Pits are generally dug about 1-2 months in advance, which helps land ripening. At this point, fill the bottom with topsoil mixed with fertilizer and flip the subsoil to the top. Planting depth should follow the original soil trace of the original seedling, too shallow is not drought-resistant, and too deep affects seedling growth. Based on many years of cultivation experience at our base, remember the walnut planting method: three burials, two treads, and one lift of the seedling. These details are very beneficial for the growth momentum of walnut trees. Smoke method: In cases where the lowest humidity does not fall below minus 2 degrees, smoke can be used in the orchard. Smoking reduces the radiative dissipation of soil heat. At the same time, smoke particles absorb moisture, causing water vapor to condense into liquid and release heat, raising the air temperature. A common smoking method involves stacking easily flammable dry grass, shavings, corn stalks, etc., with damp leaves, grass roots, sawdust, etc., layer by layer, covering the outside with a layer of soil, and inserting wooden sticks in the middle to facilitate ignition and smoke production. The smoke piles should be distributed around and inside the orchard, with more dense smoke piles upwind to quickly cover the entire orchard with smoke. The size of the smoke pile is generally no more than 1 meter high. On nights when frost is forecasted locally, fire can be lit and smoke produced when the temperature drops to 5 degrees. Artificial rainfall, spraying water, or foliar fertilization: When frost comes, use artificial rainfall equipment or spray equipment to spray water on the tree body. When water cools and solidifies, it releases latent heat and increases humidity, reducing frost damage. Foliar fertilization can increase cell concentration, with better results. Strengthen comprehensive cultivation management techniques: Enhancing tree vigor can improve frost resistance. If frost has already caused damage, active measures should be taken to strengthen management to restore yield and tree vigor. Artificial pollination should be performed on late-opening flowers to increase fruit setting rates and ensure a certain yield for the year. After tender branches and leaves are frozen, new branches and leaves will still grow, promoting their healthy growth to restore tree vigor. To buy high-quality walnut seedlings, cherry seedlings, fruit tree seedlings, come to Xinyuan Seedling Base for fruit tree planting http://www.xytymm.cn/.