As severe winter approaches, the risks of prolonged low temperatures, insufficient sunlight, and freezing rain or snow increase in some regions. To proactively mitigate the adverse effects of extreme weather on vegetable production, the Department of Crop Management of the Ministry of Agriculture and Rural Affairs, in collaboration with the National Agricultural Technology Extension Service Center, the Vegetable Expert Guidance Group of the Ministry of Agriculture and Rural Affairs, and the National Industrial Technology System for Bulk Vegetables, has formulated the following technical guidance for disaster prevention and mitigation in winter vegetable production.

I. Coping with Prolonged Low Temperature and Insufficient Sunlight

(1) Select Resilient Varieties and Cultivate Strong Seedlings

Northern greenhouse vegetable production areas: Choose cold-tolerant, low-light-resistant, disease-resistant varieties of solanaceous fruits (e.g., tomatoes, eggplants) and legumes (e.g., beans, cucumbers). Use bio-substrate seedling cultivation and moderate water control to avoid leggy or weak seedlings before transplanting.

Southern open-field vegetable production areas: Opt for cold-tolerant leafy, root, and fruit vegetables. After seedling emergence, control water and fertilizer to prevent weak growth.

(2) Enhance Insulation and Increase Soil Temperature

Greenhouse vegetables:

Install windbreaks outside greenhouses and use multi-layer insulation inside.

Maintain a distance of at least 10 cm between plastic film and plants to prevent cold damage from direct contact.

Spread rice husk ash, wood ash, or wheat bran between rows, or cover beds with straw to raise soil temperature. Heating equipment can be used if available.

Open-field vegetables:

Apply anti-freezing water via drip or sub-mulch irrigation 2 days before extreme cold to stabilize soil temperature.

Use small arches or windbreaks to protect seedlings and mature crops.

(3) Supplemental Lighting to Improve Sunlight Exposure

Install 1000W incandescent lamps (spaced 10 meters apart) for 4 hours daily in greenhouses.

If artificial lighting is unavailable, maximize natural light by early uncovering and late covering insulation materials.

Improve light penetration by pruning, trellising, reducing condensation on film, and hanging reflective film on north walls.

(4) Optimize Management: Control Water and Nitrogen

Reduce irrigation and nitrogen-based fertilization under low-temperature, low-light conditions.

If plants show signs of drought, apply drip irrigation or small amounts of sub-mulch water on sunny days, supplemented with compound fertilizers (avoid excessive nitrogen).

Foliar spray brassinolide (cold-resistance inducer), 0.3% compound fertilizer, or 0.2% calcium chloride to enhance stress tolerance.

(5) Ventilate to Reduce Humidity and Prevent Diseases

Northern greenhouses: Ventilate at midday to lower humidity; remove diseased/old leaves to improve airflow.

Southern open fields: High humidity with low light may trigger gray mold, damping-off, or sclerotinia. Apply low-toxicity, broad-spectrum fungicides to curb outbreaks.

II. Coping with Freezing Rain and Snow

(1) Monitor Weather and Reinforce Insulation

Strengthen greenhouse structures, support weak frames, and repair damaged films.

Before extreme cold, cover greenhouses with thermal blankets, add internal curtains, and seal gaps. Use heating devices if necessary.

For open-field crops, cover with plastic film, non-woven fabric, or shade nets. Do not remove covers immediately after snowmelt to avoid sudden temperature drops.

(2) Boost Plant Resistance and Disease Control

Pre-disaster foliar spray: 0.3% potassium dihydrogen phosphate + 0.3% calcium nitrate + 1% glucose, or 0.5% calcium chloride + 1% glucose (or brassinolide/sugar solutions).

Apply farmyard manure around roots and mound soil to insulate and nourish plants.

During disasters, use smoke or powder-based fungicides for low-temperature diseases. Post-disaster, remove frozen/diseased plants and spray carbendazim or chlorothalonil.

(3) Clear Snow and Drain Water

Remove snow from greenhouse roofs during snowfall to prevent collapse. In emergencies, cut films to save structures.

Post-disaster, unclog drainage ditches, clear snow, and lower groundwater levels. Dig deeper trenches in waterlogged fields.

(4) Gradual Light Exposure to Avoid Frost Damage

After sunny days return, gradually remove covers to prevent sudden wilting. Re-cover if wilting occurs and repeat until plants adapt.

Spray wilted plants with water or 1% alginate solution. Ventilate lightly at midday to reduce fog.

Remove snow from open-field plants to prevent ice formation.

(5) Harvest and Resow to Minimize Losses

Pre-disaster: Harvest mature vegetables promptly.

Post-disaster: Salvage marketable produce; replant fast-growing crops (e.g., bok choy, spinach, lettuce) in damaged fields after temperatures rise.

This guidance aims to stabilize winter vegetable production and ensure food supply resilience under extreme weather conditions.