Key Points for Protecting Winter Vegetables from Low Temperature, Limited Sunlight, and Snow

Introduction

Winter is a critical period for vegetable production, especially under extreme weather conditions such as prolonged low temperature and limited sunlight along with snow and freezing. Ensuring stable and high-quality production of winter vegetables becomes a key focus for agricultural work across various regions. To address these adverse climatic factors, this article systematically introduces key technologies and management measures for disaster prevention and reduction in winter vegetable production, helping farmers proactively prepare and respond.

Preventing and Responding to Prolonged Low Temperature and Limited Sunlight

1. Select Resistant Varieties and Cultivate Strong Seedlings

Under prolonged low temperature and limited sunlight, selecting cold-resistant, high-fruit-setting, and pest-resistant vegetable varieties is crucial. For northern facility-based cultivation, priority should be given to varieties of solanaceous and leguminous plants that are resistant to low temperatures and low light environments, along with using biological-based seedling cultivation methods. For southern open-field cultivation, choose cold-resistant and shade-tolerant leafy vegetables and root crops. After germination, manage water and fertilizer carefully to avoid leggy or weak seedlings, thus laying a foundation for smooth growth in the later stages.

2. Strengthen Insulation and Heat Retention to Improve Soil Temperature

Windbreak barriers can be set up outside facility vegetable greenhouses, and multiple layers of covering can be used inside to create an effective heat retention environment. Maintain a distance of at least 10 cm between the agricultural film and leaves to prevent cold damage caused by low temperatures. Materials such as rice husk ash, wood ash, fire soil ash, and straw can be used to cover the soil surface or between plants to raise the soil temperature and reduce low-temperature damage. For open-field vegetables, “anti-freeze water” should be applied on sunny days before extreme weather arrives, and small hoop houses or windbreak barriers can be used during low temperatures to mitigate the damage from sudden temperature drops.

3. Timely Artificial Supplementary Lighting to Increase Light

During periods of insufficient sunlight, artificial supplementary lighting should be used to promote normal photosynthesis in winter vegetables. Incandescent lamps can be installed at intervals inside the facility to provide around 4 hours of supplementary lighting each day. If conditions are limited, extending light exposure by uncovering early and covering late or cleaning the greenhouse film can help. Timely pruning, vine training, and proper ventilation can reduce plant shading and improve light efficiency.

4. Strengthen Production Management and Control Water and Nitrogen

Under low-temperature and weak-light conditions, vegetables have reduced transpiration, so irrigation and nitrogen fertilization should be controlled. If vegetables appear wilted, drip irrigation under the film or light watering can be carried out on sunny days, along with the application of multi-element compound fertilizers. Foliar spraying of cold-inducing agents such as brassinolide can also be applied to enhance plant resistance, preventing disease outbreaks or excessive growth due to over-fertilization with nitrogen.

5. Timely Ventilation to Reduce Humidity and Control Pests

In northern facility cultivation, ventilation should be done at noon on sunny days to reduce humidity inside the greenhouse and prevent the breeding of pests. Regularly remove diseased leaves, old leaves, and yellowing leaves to improve ventilation and light conditions. For southern open-field vegetables in low temperature and limited sunlight with high humidity, diseases such as gray mold, damping-off, and sclerotinia are more likely to occur. Timely application of low-toxicity, low-residue broad-spectrum fungicides can prevent disease spread.

Preventing and Responding to Snow and Freezing Weather

1. Monitor Weather Changes and Enhance Insulation and Heating

Closely monitor weather forecasts and timely maintain and reinforce vegetable production facilities. For old greenhouses or those with deformed frames, support posts can be set up in advance, and damaged greenhouse films should be repaired. Before temperature drops, thermal blankets should be covered on the outside of greenhouses, and lighting and heating equipment should be used to increase light and temperature. For open-field vegetables, plastic films and shade nets can be used as frost protection materials. However, after snow and freezing weather ends, coverings should be gradually removed when the weather improves and the temperature stabilizes.

2. Improve Plant Resistance and Control Diseases

Before snow and freezing arrive, foliar spraying of potassium dihydrogen phosphate, calcium nitrate, and glucose mixtures can be applied to enhance the cold resistance of vegetable plants. The “earth piling around roots” method can also be used, by mounding farm manure around the roots to provide heat and nutrients. During extreme weather, smoke or fine powder agents can be used to control diseases. After the disaster, promptly remove dead or diseased plants and spray broad-spectrum fungicides to prevent secondary diseases.

3. Timely Clearing of Ditches and Snow, Drainage

During heavy snow, it is necessary to clear accumulated snow from the top of the greenhouse and its surroundings in a timely manner to prevent collapse. If the snow is too thick and cannot be cleared promptly, the greenhouse film can be broken to protect the structure. After the weather improves, quickly clear drainage ditches and unclog surrounding and bed ditches to reduce water accumulation in vegetable fields, preventing excess moisture from affecting vegetable growth.

4. Gradual Uncovering of Insulation Sheets to Prevent Frost Damage

After snowfall or extreme low temperatures, when the weather turns sunny, the insulation sheets should be gradually uncovered, allowing winter vegetables to adapt to increased sunlight. If leaves appear wilted, the insulation sheets should be covered back, and once the leaves recover, they can be gradually uncovered. If necessary, water or seaweed acid solutions can be sprayed on wilted leaves to speed up plant recovery. On sunny days, small ventilation should be carried out at noon to remove mist and improve light and ventilation conditions inside the greenhouse.

5. Rush Harvesting and Replanting to Minimize Losses

Before the disaster arrives, harvest mature vegetables in time to reduce losses. After the disaster, promptly harvest any vegetables that still have market value. For fields that have been severely frozen, plowing should be carried out as soon as possible, and after the temperature rises, fast-growing vegetables such as Chinese cabbage, lettuce, mustard, spinach, or chrysanthemum greens can be replanted to ensure market supply and planting income.

Conclusion

The risks posed by low temperature, limited sunlight, and snow and freezing weather to winter vegetable production cannot be ignored. Through measures such as selecting cold-resistant and disease-resistant varieties, strengthening insulation and heat retention, timely supplementary lighting and ventilation, and scientifically applying fertilizers and pesticides, the impact of these disasters can be significantly reduced, ensuring stable production, high quality, and increased yields for winter vegetables. In the face of extreme weather, early warning monitoring and timely control should be strengthened, and remedial measures should be implemented after the disaster to lay a solid foundation for vegetable production in the coming year.