How to Grow Napa Cabbage: The Latest Cultivation Techniques and Methods Tutorial
Napa cabbage, also known as heading cabbage or yellow-bud white, originated in our country. Our country is also rich in variety resources, with high per-unit yields, generally 3500-4000 kg per mu, and over 5000 kg for high yields. Its tender leaf heads, rosette leaves or flower stalks are used for consumption, and its cultivation area and consumption volume rank first among all vegetables in China.
Botanical Characteristics of Napa Cabbage
Napa cabbage has a well-developed root system, and the radicle can form a fleshy taproot. The main root is slender, reaching up to 0.7 m in length, with many lateral root branches, and each fine root tip bears a large number of root hairs. The stem of napa cabbage is divided into the young stem, the shortened stem and the flower stem. The young stem is the epicotyl portion at the cotyledon stage, which becomes part of the main root after the cotyledons fall off. The length of the young stem is an important indicator for judging whether seedlings at the cotyledon stage are vigorous or not.
The flowers of napa cabbage are borne in an indeterminate raceme. The length of the inflorescence varies with variety. The fruit is a silique, cylindrical, with two locules and a septum in the middle, and the seeds are attached on both sides.
Cultivation Conditions for Napa Cabbage
1. Temperature: Napa cabbage prefers a mild climate. Seeds can germinate at 8-10°C, and germinate rapidly and vigorously at 20-25°C. The suitable temperature during the growing period is 10-22°C (18-22°C during the outer leaf growth stage and 12-16°C during the heart leaf growth stage). When the temperature reaches above 25°C, growth is poor; above 30°C, it cannot adapt; below 10°C, growth is slow; and below 5°C, it suffers freeze damage.
2. Light: Napa cabbage needs sufficient sunlight, and insufficient light will seriously affect the yield.
3. Soil: Napa cabbage is relatively tolerant of fertilizer and requires relatively high soil moisture and air humidity. It is suitable for planting in fertile, loose soil with strong water and fertilizer retention and good drainage. Especially during the heading stage, providing sufficient water and nitrogen fertilizer plays an important role in increasing the yield.
Cultivation Techniques for Napa Cabbage
1. Cultivation season: Early-maturing varieties are generally sown in early to mid-August, and some are sown as early as late July. Mid-maturing varieties can be sown from late August to early September. Late-maturing varieties are best sown in late August.
2. Site selection and land preparation: Continuous cropping of napa cabbage tends to cause disease, so crop rotation should be carried out, especially grain-vegetable rotation and paddy-upland rotation. When cultivating on perennial vegetable plots, continuous cropping with cruciferous vegetables should be avoided, and plots previously planted with early beans, early peppers, early cucumbers or early tomatoes can be selected. The land for planting napa cabbage should be deeply plowed 20-27 cm and left to air for 10-15 days, then the soil should be broken up and leveled, and beds 1.3-1.7 m wide, or narrow beds or high beds 0.8 m wide, should be made. When making beds, deep field ditches, waist ditches and surrounding ditches of more than 27 cm should be opened so that all ditches are connected.
3. Apply heavy basal fertilizer, mainly organic fertilizer: In mid to late July, after the previous crop is harvested, deeply turn the soil and leave it to air. When preparing the land, broadcast 100-150 kg of lime per mu. In plots where clubroot occurs, an appropriate amount of lime must also be applied in the sowing furrows. Heavy application of basal fertilizer is required, with nitrogen, phosphorus and potassium well matched. In early July, mix 40 loads of pig manure, 40-50 loads of garbage, about 75 kg of rapeseed cake and 40-50 kg of calcium magnesium phosphate per mu, add 30-40 loads of human feces and urine, moisten with an appropriate amount of water, pile it up for fermentation, cover the outside with a layer of plastic film, and let it fully decompose. Apply it in furrows when making beds. At the same time, apply 10-15 kg of 45% compound fertilizer per mu.
4. Sowing: Napa cabbage is generally direct-seeded, but can also be raised as seedlings and transplanted. Direct seeding is mainly in drills, supplemented by spot seeding. When the previous crop plot is temporarily unavailable, seedling raising and transplanting can also be used so as not to affect the cultivation season. Regardless of the method used, the soil must be finely and evenly prepared. For direct seeding, about 200 g of seed is used per mu. For seedling raising and transplanting, about 5-6 li of seedbed is needed for each mu of field, mostly by broadcast sowing, with 75-100 g of seed. After direct sowing, apply 40-50 loads of decomposed human feces and urine per mu, and combine this with covering the ground. After that, water once each morning and evening to keep the soil moist, and seedlings can emerge in 3-4 days. The row and plant spacing of napa cabbage should be determined according to the variety. Generally, early-maturing varieties are 33-50×33 cm, with 2100-2300 plants per mu; late-maturing varieties are 67*50 cm, with fewer than 2000 plants per mu. For seedling raising and transplanting, it is best to choose a cloudy day or a clear evening. To improve the survival rate, it is best to transplant small seedlings with soil, and after planting, water with setting water.
5. Field management
① Thinning: When there are 2-3 true leaves, carry out the first thinning; when there are 5-6 leaves, carry out the second thinning; when there are 7-8 leaves, the seedlings can be fixed. Select different row and plant spacings according to different varieties, leaving 1 vigorous seedling per hole. Weeding can be combined with thinning.
② Topdressing: After napa cabbage is planted and has survived, topdressing can begin. Apply 15% decomposed human feces and urine once every 3-4 days, at 4-5 loads per mu. Depending on the weather and soil moisture, dilute the human feces and urine with water before application. When napa cabbage enters the rosette stage, the concentration of topdressing should be increased, usually applying 30% decomposed human feces and urine once every 5-7 days, at 15-20 loads per mu, along with 75-100 kg of rapeseed cake or sesame cake. After heading begins, heavy topdressing and additional potassium fertilizer are necessary measures to increase yield. Apply 30-40 loads of 50% decomposed human feces per mu, and apply 100 kg of plant ash or 10-15 kg of potassium sulfate in furrows. Farmers call this fertilization "heart-filling fertilizer." After the plants close their rows, topdressing is generally no longer applied. If the basal fertilizer is insufficient, urea may be applied as appropriate between the rows.
③ Intertillage and hilling: To facilitate topdressing, loosen the soil and weed 2-3 times in the early stage. Especially after long rain turns to clear weather, timely intertillage and airing of the land should be carried out to promote root growth. In the middle of the rosette stage, combine furrow application of cake fertilizer with hilling to form ridges 10-13 cm high. The purpose of hilling is mainly to facilitate fertilization and watering and to reduce disease. After hilling, manure is poured into the ridge furrows and must not adhere to the leaves; water is poured into the furrows and must not soak the base of the plants. At the same time, keep the air circulating in the furrows to reduce the air humidity among the plants. In this way, the occurrence of soft rot can be reduced.
④ Irrigation: During the seedling stage, napa cabbage should be lightly and frequently watered to maintain moisture. During the rosette stage, irrigate intermittently, alternating dry and wet, and properly harden the seedlings. During heading, the water requirement is relatively high, and furrow irrigation can be used when the soil is dry. Irrigation should be carried out in the evening or at night after the ground temperature has dropped. Water should be let in slowly, and the bed must never be flooded. After the water infiltrates into the soil, the excess water should be drained promptly. Ensure that no water accumulates in the furrows, no water is visible on the bed surface, and the roots are not short of water. Generally speaking, from the end of the rosette stage to the middle of the heading stage, keeping the soil moist is one of the keys to achieving a high yield of napa cabbage.
⑤ Leaf tying and covering: The heading and heart formation of napa cabbage is an inevitable law of its growth and development, and leaf tying is not needed. However, if late-maturing varieties encounter severe cold, in order to promote good heading and delay harvest for supply, after Light Snow, lift the outer leaves, tie them with straw, and cover them with a layer of straw or agricultural film on top, which can protect the heart leaves from freeze damage and also has a softening effect. Early-maturing varieties do not need leaf tying or covering.
Pest and Disease Control of Napa Cabbage
The main pests and diseases of napa cabbage include: soft rot, tobacco cutworm, and others.
1. Soft rot
[Symptoms] Soft rot is also called rotten lump. It mostly begins during the heading stage. In the early stage of the disease, the outer leaves appear wilted and drooping under sunlight, but still recover in the morning and evening. As the disease develops, these diseased leaves no longer recover, exposing the leaf head. The lesions are water-soaked, and the diseased tissue turns brown, rots and becomes sticky and slippery, with a foul odor.
[Control methods] Adopt integrated control with prevention as the main principle. The specific practices are: ① Practice crop rotation. Where conditions permit, paddy-upland rotation is preferable. Do not apply disease-carrying organic fertilizer. Deep plow and sun-bleach the soil to control the source of pathogens. ② Practice high-bed cultivation, which is conducive to drainage and waterlogging prevention and can reduce the occurrence of disease. ③ Reasonable irrigation and fertilization: apply sufficient basal fertilizer and timely topdressing so that the seedlings grow vigorously and disease resistance is enhanced. ④ Promptly remove diseased plants: removing diseased plants can reduce the source of inoculum and prevent the spread of pathogens. Especially before irrigation, timely inspection and handling should be carried out. Sprinkle lime into the holes for sterilization. ⑤ Pay attention to pest control: avoid causing wounds to prevent pathogen invasion. ⑥ Select disease-resistant varieties: generally, green-stem varieties and first-generation hybrids have stronger disease resistance. ⑦ Chemical control: the following pesticides may be selected: agricultural streptomycin, one small packet added to 100 kg of water, or 70% Dexon at 600 times for root drenching; 20% Longkejun at 600 times or 47% Jiaruinong at 800 times may also be used, once every 7 days, sprayed 2-3 times in succession.
2. Tobacco cutworm
[Damage symptoms] Tobacco cutworm is also called mamma worm or lotus leaf worm. Newly hatched larvae gather on the undersides of leaves and feed, leaving only the upper epidermis and veins, so the damaged leaves look like a "screen window." After the larvae grow larger, they eat the leaves into notches, and in severe cases can eat the entire leaf, or even bite through young tender stems.
[Control methods] Tobacco cutworm has the characteristics of being omnivorous, outbreak-prone and highly reproductive, and older larvae have strong pesticide resistance. Therefore, control should focus on killing moths and destroying pupae, removing egg masses, and timely control of 1st and 2nd instar larvae.