Detailed Guide to Chinese Kale Cultivation: Management Points from Sowing to Harvest

Chinese kale is one of China's specialty vegetables, also known as white-flowered Chinese kale, green-leaf cabbage, kale, gai cai, etc. It is an annual herbaceous plant of the Brassicaceae family and Brassica genus. The flower stalks are tender, crisp, refreshingly sweet, and delicious. It is grown for its plump and tender flower stalks and young leaves, and has a very long history of cultivation in our country. Let us take a look at the cultivation techniques for Chinese kale below!

Growing Conditions for Chinese Kale

1. Temperature conditions: Chinese kale prefers a mild climate and has strong heat tolerance; its ability to withstand high temperatures is the strongest among cabbage-family vegetables. The optimum temperature for seed germination and seedling growth is 25-30°C, with growth slowing below 20°C. The optimum temperature for leaf rosette growth and flower stalk formation is 15-25°C, and it prefers a relatively large day-night temperature difference. High temperatures above 30°C are unfavorable for flower stalk development, and growth slows below 15°C. Varieties with different maturity periods differ in heat tolerance and temperature requirements for flower bud differentiation.

2. Sunlight requirements: Chinese kale is a long-day crop, but existing varieties are not strict about day length. Good light is needed throughout its entire growth and development process, and it is not shade-tolerant.

3. Moisture conditions: Chinese kale prefers a moist soil environment, with 80-90% of maximum soil water-holding capacity being suitable. It is not drought-tolerant, and its waterlogging tolerance is slightly stronger than other cabbage-family vegetables, but excessive soil moisture or water accumulation in the field will affect root growth.

4. Soil nutrition: Chinese kale has a wide adaptability to soil, with loam and sandy loam being preferable. Of the nitrogen, phosphorus, and potassium it absorbs, potassium is the most and phosphorus the least, with an N:P:K ratio of 5.2:1:5.4. Nutrient uptake is low during the seedling stage when growth is slow, and highest during the flower stalk formation stage. Since absorption of nitrogen, phosphorus, and potassium varies at each growth stage, emphasis should be placed on applying organic fertilizer, with appropriate supplementary fertilization.

Seedling-Raising Techniques for Chinese kale

1. Sowing time: Cultivation in the Beijing area can basically supply the market year-round. Early-maturing varieties such as Liuye Early Chinese Kale are grown in open fields to ensure supply from June to October. For sowing from September to March of the following year, mid-maturing and mid-late-maturing varieties such as Zhonghua and Zhongchi Kale can be selected for protected cultivation to ensure supply from November to May of the following year. Note that July to September is Beijing's hot, rainy season, so it is advisable to choose cool locations for planting.

2. Sowing method: Chinese kale can be direct-seeded or transplanted from seedlings; in the Beijing area, seedling transplanting is mostly used, requiring 75-100 grams of seed per mu. The seedling bed should be sandy loam or loam with convenient irrigation and drainage, and preferably land whose previous crop was not a Brassicaceae vegetable. When preparing the soil, apply plenty of decomposed organic fertilizer, and sow by broadcasting.

3. Seedling management: Keep the seedling bed moist at all times, apply quick-acting fertilizer 2-3 times during the seedling stage, use an appropriate sowing rate, and pay attention to thinning to avoid seedlings being too dense and growing leggy into thin, weak seedlings. At a seedling age of 25-35 days, 5 true leaves can be reached. Thinning is generally carried out after 2 true leaves appear. Select tender, strong seedlings with good growth, thick stems, and larger leaf area; small old seedlings should not be used.

Cultivation Techniques for Chinese Kale

1. Land preparation and fertilization: For Chinese kale cultivation, choose loam that retains fertilizer and water, and prepare the land finely. Apply 3000-4000 kg of decomposed pig manure or compost and 25 kg of superphosphate per mu as base fertilizer, turn them into the soil and mix evenly, then plow and level, breaking up soil clods. Generally make flat beds, but for summer cultivation, make small raised beds.

2. Transplanting method: Open-field cultivation of Chinese kale should be carried out in the afternoon, while protected cultivation is best done in the morning. After the transplanting date is determined, water the seedling bed thoroughly on the afternoon of the day before transplanting to facilitate digging up the seedlings the next day. On the day of transplanting, dig up the seedlings and transport them to the planting plot promptly, then plant them at a certain row and plant spacing.

3. Planting density: For early-maturing varieties of Chinese kale, the row and plant spacing is 25 cm × 20 cm; for mid-maturing varieties, 30 cm × 22 cm; and for late-maturing varieties, 30 cm × 30 cm. Do not plant too deep; the soil surface of the seedling block should be level with or about 1 cm lower than the bed surface. After planting, water immediately to restore growth vigor.

4. Watering and fertilizing: According to the temperature and humidity at the time, water promptly to help seedlings recover. After recovery, appropriately control watering during the leaf rosette growth stage. Once entering the flower stalk formation and harvest stages, increase the frequency of watering and keep the soil moist at all times. Base fertilizer and supplementary fertilizer are equally important; supplementary fertilizer should be applied with irrigation. Generally, 3-4 days after seedling recovery, apply a small amount of nitrogen fertilizer or dilute chicken manure, and at the bud-emergence and stalk-bolting stage, apply an appropriate quick-acting fertilizer or human manure and urine. After harvesting the main stalk, to promote the growth of side stalks, apply heavy supplementary fertilizer 2-3 times.

5. Cultivation and hilling: Chinese kale grows relatively slowly in the early stage, and weeds easily grow between plants and rows, so timely cultivation and weeding are needed. As the plant grows, the stem changes from thin to thick, being narrower at the base and larger at the top, forming a top-heavy shape. Combine cultivation with hilling and fertilizing; preferably apply 1000-2000 kg of organic fertilizer per mu.

6. Pest and disease control: Chinese kale has relatively few diseases, with black rot being common. This is a bacterial disease that easily occurs under high temperature and high humidity. Control methods include selecting disease-resistant varieties, avoiding continuous cropping with Brassicaceae vegetables, promptly removing diseased seedlings when found, and spraying fungicides such as chlorothalonil as soon as lesions are first found. In addition, in greenhouse cultivation, when the temperature is low and humidity is high, downy mildew easily occurs on leaves, stems, and flower stalks.

7. Timely harvest: When the flower stalk of Chinese kale grows level with or close to the height of the leaf tips (commonly known as "qikou hua"), it is the suitable harvest period, with a harvest height of 15-25 cm. To maintain better commercial quality, it is best to harvest in the early morning, then sort and package.