How to Manage Chinese Cabbage During the Head-Forming Stage? Key Technical Points Explained

Chinese cabbage, biennial herbaceous plant, 40-60 cm tall, usually the whole plant is hairless, sometimes with a few bristles on the midrib of the lower leaf surface. Native to northern China, it is a leafy vegetable of the genus Brassica in the family Brassicaceae, usually referring to Chinese cabbage (napa cabbage); it also includes bok choy and the cultivated variety of cabbage that forms heads, namely head cabbage, i.e. "round cabbage" or "foreign cabbage." Introduced to the south, it is cultivated throughout both northern and southern regions. It was introduced to Japan, Europe and the United States in the 19th century. There are many varieties of Chinese cabbage; northern varieties include Shandong Jiaozhou cabbage, Beijing Qingbai, Qing Tianjin Maye cabbage, Northeast Da'ai cabbage, Yutian cabbage, and Shanxi Yangcheng Da Maobian, among others. Chinese cabbage is eaten for its tender leaf heads, rosette leaves or flower stalks. Its cultivation area and consumption volume rank first among all vegetables in China. Chinese Cabbage Types The Chinese cabbage subspecies can be divided into 4 horticultural varieties: the loose-leaf cabbage variety, the semi-heading cabbage variety, the flowering-heart cabbage variety, and the heading cabbage variety. The heading cabbage variety can be divided into 3 basic ecotypes according to the cultivation center region and ecology: the upright-cylindrical type, the oval type, and the flat-head type. From the three basic ecotypes, 5 secondary types are produced: flat-head upright-cylindrical type, flat-head oval type, cylindrical type, upright-cylindrical flowering-heart type, and flowering-heart oval type. In addition to classification by ecotype, Chinese cabbage varieties can also be divided into different types according to leaf head traits and growth period. According to the number and weight of head leaves, they can be divided into leaf-weight type, leaf-number type, and intermediate type. According to the heading form of the leaf head, they are divided into closed-heart, flowering-heart or turned-heart, upright-heart, and semi-closed-heart types. According to the head top type, they are divided into flat-head, round-head, and pointed-head types. According to the way the inner leaves of the head wrap together, they are divided into overlapping-wrap, folded-wrap, twisted-wrap, and combined-wrap types. According to the growth period, they are divided into extremely early-maturing, early-maturing, mid-maturing, and late-maturing types. Growth Habits of Chinese Cabbage The growth and development process of Chinese cabbage is divided into two stages: vegetative growth and reproductive growth. The vegetative growth stage can be further divided into the following periods: Germination period: From seed sprouting and germination to emergence and the appearance of true leaves is the germination period. Under suitable temperature and soil moisture conditions, it takes about 3-5 days. Seedling period: From the appearance of true leaves to the unfolding of 5-8 leaves, forming the first leaf ring. Early-maturing varieties produce 5 leaves during the seedling period, taking about 12-15 days. Late-maturing varieties produce 8 leaves during the seedling period, taking about 17-18 days. Rosette period: After the seedling period ends, two more leaf rings form the rosette. The young inner leaves produced at the center of the plant begin to wrap together, which is the characteristic marking the end of the rosette period. This period takes about 20-21 days for early-maturing varieties and about 27-28 days for late-maturing varieties. Head-forming period: From the inner leaves beginning to wrap together to the formation of the leaf head. Early-maturing varieties take about 25-30 days, and late-maturing varieties take about 50 days. Dormancy period: The leaf head is forced into dormancy because the climate turns cold. In regions with lower winter temperatures in Northeast China, after Chinese cabbage undergoes low-temperature vernalization, it can enter the reproductive growth stage under long-day conditions, and its process can be divided into three periods: the bolting period, the flowering period, and the pod-setting period. For Chinese cabbage to transition from vegetative growth to reproductive growth, it generally requires low-temperature vernalization conditions of 2-10 degrees Celsius for 10-30 days, with late-maturing varieties having stricter requirements than early-maturing varieties. Chinese cabbage prefers mild and cool climate conditions, with an optimum growth temperature in the range of 10-22 degrees Celsius. Growth is poor above 25 degrees Celsius, and it cannot adapt above 30 degrees Celsius. Growth is slow below 10 degrees Celsius, and growth stops below 5 degrees Celsius. It can tolerate light frost but not severe frost. During the growing period, Chinese cabbage requires sufficient light conditions to facilitate photosynthesis, accumulate more substances, and promote head formation. Because Chinese cabbage has many leaves and a large leaf area, and the cuticle on the leaf surface is very thin, the amount of water transpiration is very large, so sufficient water supply must be ensured during the growing period. How to Manage Chinese Cabbage During the Head-Forming Stage? The head-forming stage of Chinese cabbage is the period when the outer leaves of autumn Chinese cabbage grow slowly, the leaf head grows rapidly, the daily increase is the largest, and nutrients accumulate in large amounts. The key management points in this period are scientific watering and fertilization, maintaining soil moisture, and ensuring robust growth of Chinese cabbage.    Applying Head-Forming Fertilizer During the growth and development of Chinese cabbage, after the outer leaves have grown to a certain number, it enters the late stage of outer leaf growth and begins to wrap and form heads. From the beginning of head formation to the firmness of the leaf head is the head-forming stage of autumn cabbage. Generally, early-maturing varieties take 25-30 days, and late-maturing varieties take about 40-50 days. The head-forming stage can also be divided into: First, the early head-forming stage, from curling to rib-pulling. This period requires 20°C-22°C during the day, 10°C-12°C at night, many sunny days, sufficient light, high soil moisture, and sufficient fertilizer, which is beneficial to the photosynthesis of outer leaves and root absorption. Second, the middle head-forming stage. The early and middle head-forming stages are the periods when inner leaves grow fastest, and 80%-90% of the weight of the leaf head is formed during these two periods. Third, the late head-forming stage. Chinese cabbage still continues to grow, and the leaf head weight still increases. Obtaining a tightly headed, white and tender leaf head is an important economic trait in autumn cabbage production. Therefore, special attention should be paid to improving the fertilizer and water management level during the head-forming stage to ensure normal growth of the leaf head and prevent the occurrence of loose heads, split heads, deformed heads, and even non-heading. It can be combined with spraying 500-fold diluted Life Element solution, spraying once at intervals of 10-15 days, for 2-3 consecutive sprays.   Fertilization should be controlled by applying one heavy fertilizer at the early head-forming stage, called "barrel-pulling fertilizer." Apply 10 kg-15 kg of ammonium sulfate or urea per mu, or combine with irrigation to apply about 1500 kg of thin manure water, or apply 50 kg-100 kg of cake fertilizer, but the cake fertilizer must be fermented and decomposed. At the same time, 7.5 kg-10 kg each of superphosphate and potassium sulfate should also be applied to promote leaf head growth. By the middle head-forming stage, apply one heart-pouring fertilizer combined with irrigation, applying 10 kg-15 kg of chemical fertilizer or 1000 kg-1500 kg of human manure and urine per mu to promote tight heading, and the topdressing method can adopt furrow application or digging pits for deep application.    Reasonable Watering Chinese cabbage grows vigorously during the head-forming stage and needs sufficient fertilizer and water supply. Generally, 2-3 irrigations are needed, and if drought weather occurs, the number of irrigations should be increased. Note that the first watering should be light irrigation to prevent sudden large watering from cracking the cabbage ribs; the second watering should follow closely to prevent surface soil from drying and cracking and causing root breakage. Irrigation should preferably adopt the furrow irrigation method, allowing water to seep in slowly, which can both ensure the water needed for Chinese cabbage growth and avoid excessive water promoting the occurrence of soft rot. Irrigation should ensure no water accumulates in the furrow, no water appears on the ridge (bed) surface, and the root system absorbs without water shortage. Stop irrigation 5-10 days before harvest to ensure improved storability of Chinese cabbage.   Tying the Cabbage Tying the cabbage can protect the leaf heads of autumn Chinese cabbage from frost damage, increase yield, reduce losses, and facilitate storage. Tying the cabbage is generally carried out 15 days before harvest, lifting the rosette leaves to wrap around the leaf head, and tying with crop straws such as sweet potato vines or millet stalks after soaking them wet. After tying, leaf photosynthesis is affected. Tying too early affects yield, and tying too late makes it susceptible to frost damage.    Timely Harvesting After the leaf heads of Chinese cabbage have grown, when the daily average temperature drops to 5°C, harvesting should begin, generally in early November, and harvesting is completed during the Minor Snow solar term.