How to Protect Greenhouse Flowers from Freezing: A Detailed Guide to Winter Management Methods

In the depths of winter, when temperatures are low, greenhouse flowers often suffer cold damage. Here are some methods for preventing cold damage.

1. Add covers. At night, surround the greenhouse flowers with straw mats or corn stalks, which can raise the temperature by 1°C to 2°C. Adding a thin mat on top of the original straw mat can raise the greenhouse temperature by 2°C to 3°C. Covering the original straw mat with a layer of plastic film not only blocks the wind but also prevents rain and snow from soaking the straw mat, thereby reducing heat loss caused by water evaporation.

2. Smoke around the greenhouse. Before a cold wave arrives, light fires around the greenhouse to produce smoke. This prevents heat around the greenhouse from radiating into the upper air and reduces heat loss.

3. Clean the greenhouse film regularly. Promptly and thoroughly remove dust, dirt and accumulated snow from the greenhouse film to increase light exposure and raise the greenhouse temperature.

4. Cover with plastic mulch or small arched tunnels. For greenhouses using high-ridge cultivation, covering the high ridges with a layer of plastic mulch can generally raise the soil temperature by 2°C to 3°C; for flat-bed cultivation, small arched tunnels can be set up to raise the soil temperature.

5. Dig cold-proof trenches. Dig trenches on the south side outside the greenhouse and fill them with insulation materials such as horse manure, weeds and straw. This prevents soil heat from escaping outward and raises the soil temperature in the southern part of the greenhouse.

6. Double-layer film covering. Stretch another layer of film beneath the anti-drip film. Because there is air between the two layers of film, the temperature inside the greenhouse can be noticeably raised.

7. Use water storage tanks for insulation. Dig a water storage tank every few meters in the center of the greenhouse, lay plastic film on the bottom of the tank, then fill it with clean water, and cover the top of the tank with a layer of transparent film (to prevent water in the tank from evaporating and increasing the air humidity inside the greenhouse). Because water has a high specific heat, it can absorb heat at noon (when temperatures are high) and release heat at night.

8. Remove and replace straw mats at the right times. When temperature conditions permit, remove them as early as possible and cover them as late as possible to promote photosynthesis in the flowers. In deep winter, on sunny days, generally remove the straw mats in the morning when sunlight falls across the entire greenhouse surface; at this time the temperature inside the greenhouse is generally not lower than 18°C. On cloudy or overcast days, when light is weaker, the straw mats should also be removed at the right time to let scattered light enter. On one hand, this can raise the temperature; on the other hand, because scattered light contains more blue-violet light, it is beneficial to photosynthesis. Never leave the straw mats in place for long periods, which would make the greenhouse dark and cold and cause the temperature to drop sharply.

9. Apply more organic fertilizer. Add heat-generating materials such as horse manure and chopped grass inside the greenhouse to raise the soil temperature. The decomposition of organic fertilizer releases heat.

10. Hang reflective screens. Hang polyester aluminized film on the north side of the greenhouse to increase light inside the greenhouse and raise the greenhouse temperature by 2°C to 3°C.

11. Use stoves or heating to raise the temperature. In extremely cold weather, add a stove or turn on heating inside the greenhouse. However, when using a stove for heating, be careful to prevent gas poisoning in the flowers (install a chimney to channel the gas outside the greenhouse). Be careful not to burn firewood or grass inside the greenhouse to raise the temperature, because the smoke released when firewood and grass burn is extremely harmful to flowers.

12. Spray antifreeze solution. Before the temperature drops, spray the stems and leaves of the plants with a 400- to 700-fold dilution of antifreeze solution, which can provide cold resistance and freeze protection.

13. Broadcast plant ash on the ground. Plant ash is grayish-black and has a strong heat-absorbing capacity. After being spread evenly on the ground, it can generally raise the soil temperature by 1°C to 2°C.