Winter Solstice Farming

During Winter Solstice, the ground across Northeast China is deeply frozen and “数九寒天” formally begins. Temperatures fall to −25 to −35°C, the frozen-soil layer continues to thicken, reaching more than 2 meters in northern Heilongjiang, snow lies deep, and all outdoor agricultural activity stops completely.
The coldest phase of “数九寒天” begins. Winter Solstice marks the starting point of the traditional “数九寒天” count: “冬至数九”, with each nine-day period counted as one “nine,” and winter ending after nine such periods, or eighty-one days. The saying “一九二九不出手，三九四九冰上走” describes the progression of the season. Winter Solstice falls within the first and second “nines”; although this is not yet the coldest point of the year—the most severe cold comes during the third and fourth “nines,” around Lesser Cold and Greater Cold—the chill is already intense and outdoor farming has stopped completely.
The traditional “猫冬” period continues throughout Northeast China. Farmers use the indoor winter months for grain-storage management, regularly checking temperature and humidity, preventing moisture, insects, and rodents, and selling flexibly according to market trends. Around Winter Solstice, grain sales enter a relatively active period and prices are comparatively high. Farmers also purchase agricultural inputs during the off-season, continue servicing machinery, and formulate the following year’s planting structure and cultivar choices according to market conditions, policy direction, and soil status. Winter Solstice is also a traditional festive day during the Northeast “猫冬” season, when families make and eat dumplings, reflected in the saying “冬至不端饺子碗，冻掉耳朵没人管.”
Winter management in pastoral areas. In eastern Inner Mongolia, livestock management enters its most difficult stage of the winter. Extremely low temperatures place heavy demands on animal energy reserves, and “数九寒天” is the hardest period of the year for livestock. Shelter temperature must therefore be protected by reinforcing sheds, increasing bedding depth, and blocking drafts; indoor temperatures should remain above 5°C, with newborn lambs and weak animals requiring additional warmth. Supplementary feeding must be precisely managed, with daily rations carefully calculated and the proportion of high-energy feed increased. High-energy feeds such as maize and sorghum should account for more than 60% of the ration so that animals have sufficient energy to withstand the severe cold. Weak livestock, pregnant females, and young animals require additional feed and higher nutritional support. Farmers must also remain alert to “白灾”, since heavy snow and blizzards are among the most common extreme-weather threats around Winter Solstice; emergency feed should be stored in advance so that animals remain adequately supplied if roads are blocked. The quality of winter livestock management directly affects survival rates and pastoral income in the following year.
Greenhouse vegetables continue supplying the market. Cucumbers, tomatoes, leafy vegetables, and other greenhouse crops continue to be harvested to meet winter demand. Winter Solstice is the period with the shortest daylight of the year, making greenhouse management especially difficult. Light management requires maximizing the available natural illumination by opening insulation covers at appropriate times and using artificial supplementary lighting when necessary. Night temperatures are also at their lowest, so additional thermal curtains or covers and temporary heating equipment may be required. Humidity must be controlled through timely ventilation to prevent diseases such as gray mold, while low-temperature, high-humidity conditions call for stronger monitoring and disease management overall.

During Winter Solstice, Northwest China enters a key winter-management stage. Winter wheat remains in deep overwintering, winter orchard management continues, and basic farmland improvement is fully complete.
Winter wheat remains in deep overwintering. Growth stops completely and plants remain in deep dormancy. During “数九寒天”, thick snow covers the fields like a protective “quilt,” insulating the crop against severe cold. Winter irrigation is fully complete and the pre-freeze watering has thoroughly recharged the soil. Farmers should inspect wheat fields regularly throughout the “数九” period, checking snow cover and signs of freezing injury; where damage is found, remedial measures such as adding protective cover or firming the snow-covered field should be taken promptly.
Winter orchard management continues. Winter pruning remains underway from leaf fall to bud break, and Winter Solstice is considered a key pruning period, reflected in the regional rhythm expressed as “冬至前后，果树修剪忙.” Orchard sanitation also continues through the removal of dead branches, fallen leaves, diseased fruit, infected branches, and weeds to reduce overwintering pests and pathogens. Trunk whitewashing continues on the lower 1–1.5 meters of the trunk to provide protection against freezing and pests. Young trees and late-autumn shoots require additional cold protection through straw wrapping, plastic-film covering, or soil mounding in preparation for the severe low temperatures of “数九寒天.”
Basic farmland improvement is fully complete. Autumn fertilization, land leveling, irrigation-facility maintenance, and shelterbelt establishment are all finished by Winter Solstice. Once the ground becomes deeply frozen after Winter Solstice, farmland construction and improvement cease entirely.

During Winter Solstice, winter wheat across North China remains in deep overwintering, “数九寒天” begins, and agricultural field activity stops completely.
Winter wheat remains in deep overwintering. Growth has stopped completely and plants remain in deep dormancy. As “数九寒天” begins, snow covers the wheat fields and provides vital insulation against freezing. The saying “冬天雪盖三层被，来年枕着馒头睡” expresses the importance of Winter Solstice snow cover as the best natural protection for winter wheat. Winter irrigation is fully complete and pre-freeze watering has thoroughly recharged the soil. Field activity ceases entirely.
“数九寒天” begins. The custom of “冬至数九” is deeply rooted across North China. The traditional rhyme reads: “一九二九不出手，三九四九冰上走，五九六九沿河看柳，七九河开，八九雁来，九九加一九，耕牛遍地走。” Winter Solstice falls within the first and second “nines,” when the cold is deepening but the most severe period still lies ahead during the third and fourth “nines,” around Lesser Cold and Greater Cold. Agricultural work stops completely and farmers enter the winter slack season, while indoor tasks continue through grain-storage management, agricultural-input purchasing, machinery maintenance, and preparation of the next year’s planting plans.
Winter Solstice is also one of the most important traditional festivals in North China. The saying “冬至大如年” reflects its significance, and families commonly eat dumplings to celebrate “一阳生,” the return of yang after the solstice.
Winter orchard management continues. Apple, pear, and other orchards continue with winter pruning, which enters a key period around Winter Solstice, together with orchard sanitation and trunk whitewashing.
Vegetable management. Greenhouse vegetables continue supplying the market, with cucumbers, tomatoes, leafy vegetables, and other crops under continuous harvest. Temperatures should be maintained at 25–28°C during the day and 12–15°C at night, with strong insulation and cold protection for the “数九寒天” period.

During Winter Solstice, the middle and lower Yangtze remains in a critical winter-management period. Rapeseed and winter wheat are in deep overwintering, while drainage and waterlogging prevention continue.
Rapeseed remains in deep overwintering. Growth largely stops and plants enter deep dormancy. The three-level drainage system of main ditches, cross-field ditches, and perimeter ditches must remain continuously functional so that water drains freely and fields dry quickly after rainfall. Although precipitation decreases during “数九寒天”, cold and damp conditions remain the greatest threat to overwintering rapeseed and can cause root rot and seedling death, so drainage management cannot be relaxed.
Weak stands receive pre-winter topdressing, based mainly on organic or compound fertilizer, to promote root development and improve cold resistance; around Winter Solstice is regarded as the best period for this application. In years of extreme cold, straw or plastic-film covering may be used for insulation, since temperatures continue falling after Winter Solstice and cold-protection preparations need to be fully in place.
Winter wheat remains in deep overwintering. Growth largely stops, while drainage and waterlogging prevention continue alongside topdressing of weak stands and cold-protection measures.
Drainage management continues. Even though rainfall decreases during “数九寒天”, the Yangtze basin can remain cold and damp enough for excessive soil moisture to develop. Keeping drainage channels clear therefore remains the primary winter-management task for both rapeseed and winter wheat.
Winter-vegetable management. Winter vegetables across the Yangtze basin remain in active growth management and require continued water and nutrient management, pest and disease control, and preparations for low temperatures.
Winter orchard management. Citrus and other orchards continue with postharvest management, orchard sanitation, winter pruning, and trunk whitewashing.

During Winter Solstice, Southwest China remains in a critical winter-management stage. Rapeseed and winter wheat are in deep overwintering, while winter potatoes enter the tuber-formation stage.
Rapeseed remains in deep overwintering. Growth largely stops. Drainage and waterlogging prevention continue, weak stands receive pre-winter fertilizer, and high-altitude areas require insulating covers to protect crops during the low temperatures of “数九寒天.”
Winter wheat remains in deep overwintering. Drainage management continues, while topdressing of weak stands and cold-protection measures proceed in parallel.
Winter potatoes enter the tuber-formation stage. Underground tubers begin to develop and enlarge, making this a critical stage for determining yield. Inter-row cultivation and earthing up are combined with fertilization to promote tuber formation and enlargement while preventing tubers from becoming exposed at the soil surface and turning green. A tuber-development fertilizer dominated by potassium is applied at a rate of 8–10 kg of potassium sulfate per *mu*, since potassium demand is high during tuber formation. Late blight also requires attention; although temperatures are low during “数九寒天”, cold and damp conditions can still trigger the disease, and mancozeb or metalaxyl may be used for control. Before further temperature declines after Winter Solstice, plastic-film or straw covering should be applied for insulation. Management during tuber formation directly affects both yield and marketable proportion.

#### (1) Mainland South China
Winter crops enter vigorous growth. During Winter Solstice, winter potatoes move into the tuber-formation stage and require stronger water and nutrient management, particularly tuber-development fertilizer dominated by potassium, together with inter-row cultivation and earthing up to prevent exposed tubers from turning green and control of late blight. Winter maize enters the tasseling and silking stage, when water supply becomes critical because drought can cause poor pollination. Panicle-stage fertilizer is applied to support ear and grain development, while maize borers, aphids, and other pests require control. Winter vegetables enter peak harvest, with choy sum, Chinese kale, spinach, lettuce, and other leafy vegetables reaching the market in large quantities. Winter crops are an important component of South China’s winter agriculture, and the quality of field management directly affects yield and quality.
Citrus reaches peak harvest. Around Winter Solstice, “砂糖橘”, “贡柑”, navel oranges, and “沃柑” continue to be harvested, and the period around the solstice is regarded as one of the best for citrus quality and market demand. Farmers take advantage of clear weather to pick, grade, pack, and sell the fruit, while harvest timing and postharvest handling directly affect market prices and farm income.
Cold and frost protection. Although the “数九寒天” period in South China is far milder than in the north, occasional low-temperature frost still threatens winter crops and tropical fruit trees. Protective measures include plastic-film or straw covering, which can raise surface temperature by 2–3°C; irrigation before frost 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. All cold-protection work needs to be completed before low temperatures arrive.
#### (2) Taiwan
Rice: Rice harvesting is fully complete across Taiwan and fields enter either the winter slack period or the winter-cropping stage.
Vegetables: During Winter Solstice, winter vegetables across Taiwan enter peak harvest.
Fruit trees: Citrus reaches peak harvest, while banana harvesting approaches completion.
Tea: Tea gardens in central and southern areas such as Nantou and Chiayi enter winter management, as do northern tea-growing areas such as Wenshan and Sanxia.
Fisheries: Fishing continues in waters around Taiwan during Winter Solstice, while 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 “冬至大如年”, reflecting the status of Winter Solstice as one of the island’s most important traditional festivals, when families roll tangyuan and make ancestral offerings. “冬至圓仔呷落加一歲” expresses the belief that eating tangyuan at Winter Solstice symbolizes becoming one year older. Another saying, “冬至有雨雨水多，冬至无雨雨水少”, uses the weather on Winter Solstice to predict rainfall in the coming year. Winter Solstice is also an important season for “补冬”, when warming and nourishing foods such as mutton and sesame-oil chicken are traditionally eaten.