I. Core Strategy 1: Multi-Layer Insulation & Emergency Heating

1. Multi-Layer Coverage for Heat Retention

• External Insulation: Cover the greenhouse exterior with thermal blankets (preferably with a water-resistant coating) or straw mats, and add a layer of polyethylene film on top. This prevents insulation materials from absorbing moisture (which drastically reduces their thermal performance) and enhances wind resistance. For gutter-connected greenhouses, focus on sealing gaps between spans with weatherstripping.
• Internal Insulation: Set up low-tunnel greenhouses (small arch shelters) above the seedling beds, using 0.08-0.1mm thick EVA film with anti-fog and anti-drip functions. This creates a "microclimate zone" that raises local temperature by 3-5℃, ideal for tender seedlings like tomatoes and peppers.
• Perimeter Reinforcement: Stack 2-3 layers of straw curtains or thermal insulation boards around the greenhouse, at the base of the rear wall, and along the lower edges of the side walls. Install buffer films at ventilation openings and doorways to block cold air infiltration—this simple measure can reduce indoor temperature loss by 15%-20%.

2. Emergency Heating Equipment Preparation

II. Core Strategy 2: Light Enhancement to Boost Cold Resistance

1. Maximize Natural Light Utilization

• Clean the greenhouse film 2-3 times a week (especially before snowfall) to remove fog, dust, and algae—this can improve light transmittance by 10%-15%. Replace aging films (used for over 12 months) with high-transparency PO films (light transmittance ≥90%).
• Prune old, diseased, and overlapping leaves promptly to reduce light competition between plants. For vine crops like cucumbers, use vertical trellises to optimize light exposure for lower leaves.
• Hang aluminum foil reflective screens on the rear wall of the greenhouse, angled at 45° to redirect scattered light to the northern area of the greenhouse—this increases light intensity in shaded zones by 30%.

2. Scientific Supplementary Lighting

• Light Source Selection: LED grow lights (660nm red light + 450nm blue light) are preferred for energy efficiency; high-pressure sodium lamps are suitable for large-area supplementary lighting (1000W per 100㎡).
• Lighting Parameters: Maintain a light intensity of 300-500 μmol/m²/s for leafy vegetables and 500-800 μmol/m²/s for fruiting vegetables; light for 4-6 hours daily (9:00-11:00 and 14:00-16:00 for optimal efficiency).

III. Core Strategy 3: Nutrient Regulation to Strengthen Plant Vitality

1. Base Fertilizer & Topdressing Optimization

• Apply 3000-5000 kg/ha of fully decomposed organic fertilizer (such as composted cow manure) as base fertilizer, combined with 150 kg/ha of phosphorus pentoxide (P₂O₅) and 200 kg/ha of potassium oxide (K₂O) to promote root development and cell wall thickening.
• 10-15 days before the expected cold wave, apply functional fertilizers (humic acid, seaweed extract, or chitin) at 50-80 kg/ha via drip irrigation to activate root activity and enhance stress resistance.

2. Foliar Nutrition for Rapid Stress Resistance

• Mix amino acid solution (180 g/L) + humic acid (50 g/L) + potassium dihydrogen phosphate (0.3%) and spray once every 7-10 days. This enhances the activity of anti-freeze proteins in leaf cells.
• For fruiting vegetables (e.g., tomatoes), add 0.1% brassinolide to the spray to promote nutrient translocation and flower bud protection.

IV. Critical Response: Post-Frost Management to Minimize Losses

1. Slow Temperature Rise After Sudden Clear Weather

• In the morning, retract only 1/3 of the thermal blankets or straw curtains; gradually increase the area by 1/3 each day.
• If using shade nets, deploy them at noon (11:00-14:00) to reduce light intensity. Normal curtain management can resume after 2-3 days when the soil temperature rises to 12℃ or above.

2. Cold Damage Recovery Measures

1. Initial Treatment (1-3 Days After Damage): Avoid flood irrigation. Spray chelated amino acid magnesium-calcium solution (180 g/L amino acids, 20 g/L Ca, 10 g/L Mg) diluted 600x, 300-450 L/ha. Repeat after 5 days to repair leaf cell tissue.
2. Mid-Term Recovery (4-7 Days After Damage): Implement integrated water-fertilizer-pesticide treatment via drip irrigation: 150 mL/ha azoxystrobin SC + 500 mL/ha thiazole zinc SC + 500 mL/ha amino acid solution. This prevents fungal/bacterial diseases and boosts root vitality.
3. Later Regulation (1-2 Weeks After Damage): Maintain night temperature 2-3℃ higher than usual; spray 25% glucose solution (800-1000x) or 180 g/L amino acid solution (1000-1500x) to restore metabolic balance. Combine with 100 kg/ha potassium dihydrogen phosphate via irrigation to enhance stress resistance.

V. Key Takeaways for Frost Protection