1. Drying method: Wash the scallion, dry it in a cool and ventilated place for a few days, and then store it in a cool place after its surface is dry. This can keep the freshness of green onions and keep them for a long time.

2. Refrigeration method: put the scallion into a fresh-keeping bag, remove the air, tie the bag tightly and put it in the refrigerator for preservation. This can keep the freshness of green onions for a period of time.

3. Freezing method: Chop or cut green onions, put them in fresh-keeping bags, remove air, tie the bags tightly, and store them in the freezer. This can be kept for a long time, but it needs to be thawed when necessary.

4. Pickling method: Chop or cut the green onions, add seasonings such as salt and sugar for pickling, and then store them in a sealed container. This can be preserved for a period of time, but be careful not to eat too much pickled food.

No matter which method is used to preserve green onions, they should be kept in a dry and cool environment to avoid direct sunlight and high temperature, so as not to affect the preservation effect of green onions. At the same time, we should pay attention to the hygiene and quality of food to avoid food deterioration and bacterial growth.