How to water greenhouse vegetables in winter and spring? Master the scientific method

In winter and spring, the air temperature is low and the water temperature is also low. After each watering, the soil temperature drops greatly, which not only prevents the greenhouse vegetables from growing normally for several days, but also causes increased humidity inside the greenhouse after watering, inducing the occurrence of various moisture-loving diseases such as gray mold, downy mildew and leaf mold, thus directly affecting vegetable yield, quality and profitability. So, how should you water to achieve the best results? Specifically, the following points should be done:

I. Look first

1. Look at growth vigor. Look at the plant's growth vigor. Usually when plants lack water, the leaves wilt, growth vigor weakens, and blossom-end rot of the fruit occurs more often. At this time, water should be supplemented promptly.

2. Look at soil moisture. Look at the soil moisture. If you water when the greenhouse soil is not dry, it is not only unfavorable for raising the soil temperature, but also easily leads to poorer soil aeration, causing root oxygen deficiency, root rot, and the appearance of yellow leaves.

3. Look at the weather. Before watering, be sure to watch the weather forecast. Not only should you choose a sunny day for watering, but you should also ensure there are 2-3 sunny days after watering, so as to avoid encountering overcast and rainy weather after watering, which would increase humidity inside the greenhouse, lower the soil temperature and cause frequent diseases. In deep winter this needs even more attention. In the first two days after a sudden clearing following consecutive overcast days, watering is also not suitable. The greenhouse temperature and soil temperature should be raised first, so that the plants basically return to normal before watering.

4. Look at the soil temperature. The suitable average daily soil temperature for vegetable growth is about 22°C, while in deep winter, the soil temperature inside the greenhouse is mostly 15°C-20°C. If too much water is applied or the timing of watering is wrong, the soil temperature will drop rapidly, causing root injury and endangering the growth of the aboveground part of the plant. Therefore, when watering at low temperatures, it is best to do so in the morning after the straw mat covering is rolled up.

II. Then pay attention

1. Pay attention to covering with plastic film. Covering with plastic film can not only reduce water evaporation from the ground, maintain soil moisture, lower air humidity and reduce disease occurrence, but also raise the soil temperature and speed up vegetable growth.

2. Pay attention to moderate watering. For watering greenhouse vegetables in winter and spring, generally follow the principle of not watering unless there is a shortage and preferring dry over wet, keeping the soil water content in the crop root zone at about 60%, preventing excessive and too frequent watering, and absolutely avoiding flood irrigation. Overwatering easily lowers the air temperature and soil temperature inside the greenhouse, which is unfavorable for crop growth. In winter and spring, greenhouse vegetables should be watered frequently with a small amount, or watered plant by plant with a watering can. This can basically meet the crop's growth needs and also prevent the greenhouse temperature from dropping markedly and the humidity from increasing markedly, thereby suppressing the massive occurrence of diseases and insect pests.

3. Pay attention to timely watering. When vegetables wilt and tendrils cannot extend and hold up normally, it indicates a water shortage, and watering should be done promptly. Watering should preferably be done around noon on a sunny day, and after watering, ventilate appropriately to dissipate moisture, preventing excessive humidity inside the greenhouse from causing the occurrence and spread of diseases and insect pests. In particular, tomato gray mold and cucumber downy mildew are extremely prone to occur under high temperature and high humidity conditions.

4. Pay attention to regulating water temperature. When the water temperature differs from the greenhouse temperature by more than 5°C, it easily causes root damage. Using deeper well water with a higher water temperature, or pre-storing irrigation water inside the greenhouse, is better.

5. Pay attention to concealed irrigation under the film. For greenhouse vegetables such as cucurbits, solanaceous fruits and beans, plastic film mulching cultivation should be adopted during cultivation. When irrigating, concealed irrigation under the film should be used. The plastic film can be used to heat the water temperature and soil temperature, and also suppress excessive evaporation of water, prevent excessive humidity inside the greenhouse, and avoid the occurrence and spread of diseases and insect pests.