Key points for managing greenhouse vegetables in low-temperature winter: insulation, humidity control and disease prevention

Managing greenhouse vegetables in low-temperature winter refers to a series of regulation measures taken around the conditions of temperature, humidity, light, water and fertilizer inside the greenhouse during the season when the outside air temperature drops noticeably and sunshine hours shorten. During this period, the temperature difference inside and outside the greenhouse is large, vegetables grow slowly, and improper management can easily lead to problems such as freezing injury, stiff seedlings and the spread of diseases, which directly affects the success or failure of winter cultivation.

Insulation is the core of management during the low-temperature period. In production, heat loss is often reduced by thickening the greenhouse film, adding a second curtain or small arch shed, and covering insulation quilts or straw curtains at night, while wind protection is also done well at the door and ventilation openings. When the weather is clear, ventilation can be carried out for a short time at noon when the temperature is relatively high, which can both supplement carbon dioxide and discharge moisture, avoiding keeping the greenhouse sealed for a long time just to preserve heat.

In terms of water and fertilizer, it is better to control than to promote. At low temperatures, the root absorption capacity is weak, so watering should be done in the morning on clear, warm days, in small amounts and multiple times, preferably by drip irrigation under film, to prevent flooding irrigation from causing a sudden drop in soil temperature; topdressing can be combined with decomposed organic fertilizer or water-soluble fertilizer, and it is important not to apply nitrogen fertilizer alone. Normally, the greenhouse film should also be wiped frequently to maintain light transmission, and during consecutive cloudy days, supplementary lighting can be appropriately used when conditions permit to maintain basic photosynthesis.

A low-temperature and high-humidity environment easily induces diseases such as gray mold and downy mildew. Prevention and control should focus on reducing humidity and ventilating, and when necessary, smoke agents, dusts and other methods should be chosen for pesticide application to minimize humidity inside the greenhouse. Pruning, leaf removal, harvesting and other farming operations should preferably be arranged on sunny days, and moisture should be dispersed promptly after operations to reduce the risk of wound infection.

Doing a good job of greenhouse management during the low-temperature winter period can not only reduce losses caused by cold waves and consecutive cloudy days, but also help stabilize yield and quality and ensure the supply of vegetables in winter and spring. All regions should also flexibly adjust measures according to local climate and planted varieties, by observing the weather, the seedlings and the greenhouse conditions.