What are the measures to protect greenhouse vegetables from freezing?

1. Strengthen covering. Build small arch tunnels inside the greenhouse, using thin bamboo poles as arches, cover them with plastic film at night, cover the film with straw mats, and cover the ground inside the greenhouse with plastic mulch, which can raise temperature and retain moisture. Use plastic film as a skirt around the bottom inside the greenhouse, which can noticeably reduce cold air intrusion at the bottom. At the same time, be sure to plug gaps in the greenhouse to minimize heat loss through them. On the north side of the greenhouse, pile crop straw into a windbreak to block wind and protect against cold.

2. Temporary heating. When the daytime temperature inside the greenhouse is below 15°C and the nighttime temperature is below 5°C, chilling injury or freezing injury may occur. Temporary heating measures should be taken at night to supplement heat artificially, such as placing several coal ball stoves inside the greenhouse to raise the temperature inside. However, be careful to prevent carbon dioxide poisoning; when adding coal balls and taking out the coal stoves, ventilate first, then enter.

3. Strengthen fertilizer and water management. Before and during a cold wave, stop applying nitrogen fertilizer to vegetables to prevent the plants from becoming too soft, their cold resistance from declining, and fertilizer damage from killing the seedlings. You can spray a 0.3%-0.5% potassium dihydrogen phosphate solution and a 400-500 times diluted plant antifreeze solution, and water the greenhouse with dilute manure water so that the soil does not easily freeze, achieving the goal of protecting seedlings and preventing cold damage.

Feng Guanglai, Vegetable Station, Agriculture and Animal Husbandry Bureau of Chengde County