Minor Cold Farming

During Lesser Cold, Northeast China remains deeply frozen and the severe cold of “三九” arrives in full force. Temperatures fall to −25 to −35°C, with some areas dropping below −40°C. The frozen-soil layer reaches its maximum thickness, exceeding 2 meters in northern Heilongjiang, and snow cover becomes deep. The saying “小寒大寒，冻成冰团” captures this period as one of the coldest of the year.
The severe cold of “三九” brings deep freezing. The harshest phase of “三九” usually occurs during Lesser Cold, as reflected in the saying “一九二九不出手，三九四九冰上走.” Lesser Cold often coincides with the height of this severe cold. Outdoor agricultural activity stops completely, the ground is deeply frozen, and rivers are fully icebound.
Agricultural activity shifts entirely indoors. Farmers continue managing stored grain, regularly checking temperature and humidity, preventing moisture, insects, and rodents, and preparing sales as the Spring Festival approaches, when grain marketing enters a favorable period. Off-season purchasing of seeds, fertilizers, pesticides, agricultural film, and other inputs continues, as does winter servicing of farm machinery. Farmers also determine the next year’s crop structure and cultivar choices according to market conditions, policy direction, and climate trends. Lesser Cold is the coldest period in Northeast China and the time when “猫冬” is at its most complete.
The most difficult period of winter management in pastoral areas. In eastern Inner Mongolia, livestock management enters its hardest stage of the year. The severe cold of “三九” imposes the greatest physical stress on animals and corresponds to the highest mortality risk. Shelter temperatures must therefore be protected by reinforcing sheds, increasing bedding depth, and blocking drafts, with indoor temperatures kept above 5°C. Newborn lambs and weak animals require special warming measures through group separation, additional bedding, and, when necessary, heat lamps.
Supplementary feeding must be carefully calculated, with the proportion of high-energy feeds increased. Maize, sorghum, and other energy-rich feeds should account for more than 60% of the ration, while protein sources such as soybean meal and cottonseed meal should also be increased so that livestock receive enough energy and protein to withstand severe cold. Weak livestock, pregnant females, and young animals need additional feed and higher nutritional support. Blizzards are among the most common extreme-weather threats during Lesser Cold, so farmers must guard against “白灾” by closely monitoring forecasts and storing emergency feed in advance. The quality of winter livestock management directly affects overwintering survival and pastoral income in the following year.
The most difficult period for greenhouse-vegetable management. During Lesser Cold, greenhouse vegetables enter their most demanding management period because the severe cold of “三九” creates the hardest conditions of the year. Insulation must be strengthened through second-layer curtains or thermal covers at night, reinforcement of greenhouse frames against wind and snow, and strict prevention of cold-air intrusion. Night temperatures should remain above 12°C because lower temperatures inhibit crop growth.
During extreme cold, temporary heating equipment such as hot-air furnaces or electric heaters may be needed to keep greenhouse night temperatures above 8–10°C, while heat-loving crops such as tomatoes and cucumbers should remain above 12°C. Because daylight remains very short, growers need to maximize natural light by opening thermal covers promptly, cleaning greenhouse films to improve light transmission, and using artificial supplementary lighting when necessary. Humidity should be reduced through short periods of ventilation around midday when outside temperatures are relatively higher, helping prevent gray mold and other diseases. Low-temperature, high-humidity conditions also favor gray mold and downy mildew, requiring close monitoring and timely control.

During Lesser Cold, Northwest China remains in a critical winter-management stage. Winter wheat is in deep overwintering, while winter orchard management continues through the severe cold of “三九.”
Winter wheat remains in deep overwintering. During the severe cold of “三九”, wheat fields are covered by snow, as described in “小寒大寒，冻成冰团”, and this snow layer provides insulation against freezing. Winter irrigation is fully complete and the pre-freeze watering has thoroughly recharged the soil. Farmers should inspect fields regularly during this severe-cold period, checking both snow coverage and signs of freezing injury. Where snow cover is insufficient, snow may be redistributed manually or straw applied as insulation.
Winter orchard management continues. Despite the severe cold of “三九”, winter orchard work continues. Winter pruning proceeds through Lesser Cold and Greater Cold, with growers working in the orchards even under harsh conditions; “三九严寒修剪忙” aptly describes this winter rhythm in Northwest China. Orchard sanitation and trunk whitewashing also continue. The severe cold of “三九” is a critical period for fruit-tree frost protection, especially for young trees and late-autumn shoots, which require straw wrapping, plastic-film covering, or soil mounding to prevent freezing injury or death.
Basic farmland improvement is fully complete. All farmland improvement work was finished before Winter Solstice. By Lesser Cold, the land is deeply frozen and construction or improvement work in the fields has stopped completely.

During Lesser Cold, winter wheat remains in deep overwintering across North China and agricultural field activity stops completely under the severe cold of “三九.”
Winter wheat remains in deep overwintering. Wheat fields are covered by snow during “三九”, providing insulation and protection against freezing. Winter irrigation is fully complete and pre-freeze watering has thoroughly recharged the soil. This is the most critical phase of winter-wheat overwintering: fields with adequate snow cover can pass through the severe cold more safely, while fields without snow face a much greater risk of freezing injury. Farmers therefore need to inspect wheat fields regularly throughout “三九” for signs of damage.
Agricultural activity stops completely during “三九.” There is no outdoor field work across North China during Lesser Cold and farmers fully enter the winter slack season. Indoor work nevertheless continues through grain-storage management, with grain sales entering a busy period as the Spring Festival approaches, continued off-season purchasing of agricultural inputs, winter servicing of farm machinery, and preparation of the next year’s planting plans.
Lesser Cold is also part of the seasonal food culture following the dumpling traditions of Winter Solstice and leading into Lesser Cold and Greater Cold. The saying “小寒大寒，冻成冰团” expresses the depth of the cold, while folk custom includes eating warming foods such as mutton and chicken soup.
Winter orchard management continues. Apple, pear, and other orchards continue winter pruning despite the severe cold, laying the groundwork for the following year’s harvest, while orchard sanitation and trunk whitewashing also continue.
Vegetable management. Greenhouse vegetables continue supplying the market, but “三九” is the most difficult management period of the year. Temperatures should be maintained at 25–28°C during the day and 12–15°C at night, with additional insulation covers, strict protection against cold-air intrusion, and temporary heating equipment prepared when necessary.

During Lesser Cold, the middle and lower Yangtze remains in a critical winter-management phase. Rapeseed and winter wheat are in deep overwintering, and both drainage management and cold protection become equally important during the severe cold of “三九.”
Rapeseed remains in deep overwintering. Growth stops completely and plants enter deep dormancy. The three-level drainage system of main ditches, cross-field ditches, and perimeter ditches must remain open and functional so that excess water drains efficiently after rainfall. Although precipitation declines during “三九”, cold and damp conditions remain the greatest threat to overwintering rapeseed, so drainage management cannot be relaxed.
Cold protection also becomes critical. During years of extreme low temperatures, straw or plastic-film covering may be used to conserve heat, with particular attention given to cold upland areas and low-lying fields. Weak stands that did not receive pre-winter topdressing around Winter Solstice should be supplemented during Lesser Cold, using mainly organic or compound fertilizer to promote root development and improve cold tolerance. The quality of overwintering management directly affects survival and yield the following year.
Winter wheat remains in deep overwintering. During the severe cold of “三九”, drainage management continues, while cold protection and management of weak stands proceed in parallel.
Drainage and cold protection are equally important. Across the Yangtze basin, cold and damp conditions during “三九” can cause freezing injury and waterlogging injury at the same time, creating greater damage to crops. Farmers therefore need both to maintain effective drainage and to use insulating covers where necessary.
Winter-vegetable management. Winter vegetables remain either in active growth or harvest and require continued water and nutrient management, pest and disease control, and protection through insulating covers before frost.

During Lesser Cold, Southwest China remains in a critical winter-management stage. Rapeseed and winter wheat remain in deep overwintering, while winter-potato management continues through the key tuber-enlargement period.
Rapeseed remains in deep overwintering. Growth largely stops during “三九.” Drainage and waterlogging prevention continue, while cold protection becomes especially important in high-altitude areas where low temperatures represent the main threat to overwintering rapeseed. Weak stands may also receive pre-winter fertilizer.
Winter wheat remains in deep overwintering. During the severe cold of “三九”, drainage management continues while cold protection and management of weak stands proceed in parallel.
Winter potatoes remain in the critical tuber-enlargement stage. Underground tubers continue to develop and enlarge despite the severe cold. Inter-row cultivation and earthing up are carried out together with fertilization to encourage tuber enlargement and prevent tubers from becoming exposed at the soil surface and turning green. Thicker soil cover during “三九” can also help raise soil temperature and protect tubers against freezing.
A tuber-development fertilizer dominated by potassium is applied at a rate of 8–10 kg of potassium sulfate per *mu*. Late blight is less common under the severe cold of “三九”, but fields still require monitoring, with mancozeb or metalaxyl used where needed. Before low temperatures arrive, plastic-film or straw covering should be applied for insulation, since “三九” is the most critical period for protecting winter potatoes against cold.

#### (1) Mainland South China
Winter crops move from vigorous growth toward maturity. During Lesser Cold, temperatures in South China remain relatively mild despite the severe cold of “三九”, allowing winter crops to continue normal growth. Winter potatoes advance from tuber enlargement toward maturity and require stronger water and nutrient management, particularly tuber-development fertilizer dominated by potassium, continued late-blight control, and timely harvesting as early cultivars begin to mature.
Winter maize advances from grain filling toward maturity and requires adequate water because drought during grain filling can reduce thousand-grain weight. Maize borers, aphids, leaf-spot diseases, and other pests and diseases still require control, while early cultivars begin to be harvested. Winter vegetables reach peak harvest, with choy sum, Chinese kale, spinach, lettuce, and other leafy vegetables entering the market in large quantities. Winter crops form an important part of South China’s winter agriculture, and Lesser Cold is a critical stage for both yield formation and harvest.
Citrus harvesting continues. “砂糖橘”, “贡柑”, navel oranges, and “沃柑” remain under active harvest. With the Spring Festival approaching, citrus enters a busy marketing season, and farmers take advantage of clear weather to pick, grade, pack, and sell the fruit. Citrus harvesting and marketing are among the most important agricultural activities in South China during Lesser Cold.
Cold and frost protection becomes a priority. Although South China is warmer than the north, the severe cold of “三九” can still bring low temperatures and frost, threatening winter crops and tropical fruit trees. Protective measures include plastic-film or straw covering, which can raise surface temperatures by 2–3°C; pre-frost irrigation to increase soil heat capacity; smoke-frost protection in orchards to raise near-ground temperatures by 2–3°C; and application of anti-freeze agents to fruit trees to strengthen cold resistance.
#### (2) Taiwan
Rice: Rice harvesting is fully complete across Taiwan and fields remain in either the winter slack period or winter-cropping stage.
Vegetables: During Lesser Cold, winter vegetables across Taiwan reach peak harvest.
Fruit trees: Citrus harvesting continues, while banana harvesting approaches completion.
Tea: Winter management continues in tea gardens across central and southern areas such as Nantou and Chiayi, as well as northern producing regions such as Wenshan and Sanxia.
Fisheries: Fishing continues in waters around Taiwan during Lesser Cold. The northeast monsoon remains active and maritime operations require continued attention to safety.
Farmer’s proverbs and folk customs: Taiwanese folk tradition preserves the saying “小寒大寒，無風也寒”, describing how cold the Lesser Cold and Greater Cold period feels even without wind. Another saying, “小寒不寒，清明泥潭”, suggests that if Lesser Cold is not cold, the following Qingming period may be especially rainy. There is also the seasonal food custom “小寒吃羊肉，大寒吃萝卜”, with mutton traditionally eaten during Lesser Cold as a warming food against winter cold.