Key Points for Protecting Winter Vegetables from Low Temperatures, Low Light, Rain, and Snow

Introduction

Winter is a critical period for vegetable production due to severe challenges, especially under continuous low temperature and low light and freezing rain and snow conditions. Ensuring stable and high-quality production of winter vegetables has become a key focus of agricultural work across regions. To cope with these adverse weather conditions, this article systematically introduces key technologies and management measures for disaster prevention and mitigation in winter vegetable farming, helping farmers proactively prepare for and respond to extreme weather.

Coping with Continuous Low Temperature and Low Light Weather

1. Select Stress-Resistant Varieties and Cultivate Strong Seedlings

Under continuous low temperature and low light conditions, selecting cold-tolerant, high fruit-setting, and disease-resistant vegetable varieties is crucial. For protected cultivation in northern regions, varieties tolerant of low temperatures and low light, such as solanaceous and cucurbit crops, should be prioritized, and biological substrate seedling methods should be used. In southern open-field cultivation, cold-resistant leafy and root vegetables preferring low light are suitable. After emergence, moderate control of water and fertilizer should be applied to avoid leggy or weak seedlings, laying a solid foundation for subsequent growth.

2. Strengthen Heat Preservation and Increase Soil Temperature

For greenhouse vegetables, windbreak barriers can be set up outside, and multi-layer coverings can be used inside to create an effective heat preservation environment. Maintain a 10 cm gap between the agricultural film and leaves to prevent frost damage due to low temperatures. Materials like rice husk ash, plant ash, and straw can be applied on the bed surface to increase soil temperature and reduce cold damage. For open-field vegetables, irrigation with antifreeze water on sunny days before extreme weather and setting up small tunnels or windbreaks during low temperatures can reduce losses caused by sudden temperature drops.

3. Artificial Light Supplementation When Necessary

During periods of insufficient sunlight, artificial light supplementation can promote normal photosynthesis of winter vegetables. Incandescent lamps can be installed at intervals in greenhouses, providing about 4 hours of additional light daily. If resources are limited, increasing light duration by early opening and late closing of coverings and cleaning the film can also help. Timely pruning, vine tying, and proper ventilation can further enhance light efficiency.

4. Strengthen Management and Control Water and Nitrogen

Under low temperature and weak light conditions, vegetable transpiration is reduced. Therefore, irrigation and nitrogen fertilizer application should be moderately controlled. If wilting occurs, drip irrigation under the film or small-scale watering should be conducted on sunny days, combined with multi-element compound fertilizer application. Foliar sprays of brassinosteroids and other cold-resistance inducers can enhance stress tolerance and prevent excessive nitrogen fertilizer from causing diseases or overgrowth.

5. Timely Ventilation to Reduce Humidity and Prevent Pests

In northern greenhouse cultivation, ventilation should be conducted at noon on sunny days to reduce indoor humidity and prevent pest outbreaks. Diseased, old, and yellow leaves should be regularly removed to improve ventilation and light conditions. In southern open-field cultivation, where low temperature and low light combined with high humidity may induce gray mold, damping-off, and sclerotinia, timely spraying of low-toxicity, low-residue broad-spectrum fungicides is necessary to prevent disease spread.

Coping with Rain, Snow, and Freezing Weather

1. Monitor Weather Changes and Enhance Heat Preservation

Closely monitor weather forecasts and promptly maintain and reinforce vegetable production facilities. For old or deformed greenhouses, support columns should be installed in advance, and damaged film should be repaired. Before temperature drops, thermal insulation blankets can be placed outside the greenhouse, and light supplementation and heating devices can be used to enhance light and temperature. Open-field vegetables can be covered with plastic film or shade nets for cold protection. However, after rain, snow, and freezing weather ends, coverings should be gradually removed when the weather improves, and temperatures stabilize.

2. Enhance Plant Resistance and Prevent Diseases

Before the arrival of rain, snow, and freezing, foliar sprays of potassium dihydrogen phosphate, calcium nitrate, and glucose mixtures can be applied to enhance the cold resistance of vegetable plants. Root protection can also be done by piling organic fertilizers around the root zone to provide heat and nutrients. During extreme weather, fumigants or powders can be used to prevent diseases. After the disaster, dead and diseased plants should be promptly removed, and broad-spectrum fungicides should be sprayed to prevent secondary infections.

3. Clear Drainage Channels and Remove Snow in Time

During heavy snow, timely removal of accumulated snow from greenhouse roofs and surroundings is necessary to prevent structural collapse. If snow accumulation is too heavy to clear immediately, breaking the film to save the structure may be necessary. After the weather improves, drainage ditches should be promptly cleaned, and surrounding and furrow channels should be unblocked to reduce waterlogging and prevent excessive moisture from affecting vegetable growth.

4. Gradually Remove Insulation and Avoid Frost Damage

After snowfall or extreme low temperatures, insulation should be gradually removed when sunny weather returns to allow winter vegetables to adapt to increased light. If leaf wilting occurs, the insulation should be replaced, and once the leaves recover, it should be gradually removed again. If necessary, spraying water or seaweed extract on wilted leaves can accelerate recovery. Small ventilation at noon on sunny days can help dissipate fog and improve light and air conditions inside greenhouses.

5. Timely Harvest and Replant to Reduce Losses

Before the disaster strikes, mature vegetables should be harvested to reduce potential losses. After the disaster, vegetables with commercial value should be harvested promptly. Severely frost-damaged fields should be replowed as soon as possible. Once temperatures rise, quick-growing vegetables such as bok choy, lettuce, mustard greens, spinach, or garland chrysanthemum can be replanted to ensure market supply and planting income.

Conclusion

The climatic risks of low temperature and low light and rain, snow, and freezing in winter vegetable production cannot be ignored. Through the selection of cold-resistant and disease-resistant varieties, strengthening heat preservation, timely light supplementation, ventilation, and scientific fertilizer and pesticide use, the impact of adverse weather can be significantly reduced, ensuring stable, high-quality, and increased winter vegetable production. During extreme weather, early warning and timely prevention should be strengthened, and post-disaster remedial measures should be taken to lay a solid foundation for vegetable production in the coming year.