How to Grow Chinese Broccoli (Gai Lan)? The Latest Cultivation Techniques and Method Tutorial

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

Cultivation Conditions for Gai Lan

1. Temperature conditions: Gai lan likes 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. Below 20°C, growth is slow. The optimum temperature for leaf cluster 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 below 15°C growth is slow. Varieties with different maturity characteristics differ in their heat tolerance and temperature requirements for flower bud differentiation.

2. Sunlight requirements: Gai lan is a long-day crop, but existing varieties are not strict about day length. Its entire growth and development process requires good light, and it is not shade-tolerant.

3. Moisture conditions: Gai lan likes 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 that of other cabbage-family vegetables, but excessive soil moisture or standing water in the field will affect root growth.

4. Soil nutrients: Gai lan has a relatively wide adaptability to soil, with loam and sandy loam being preferable. Of the nitrogen, phosphorus and potassium it absorbs, potassium is taken up the most and phosphorus the least, with an N:P:K ratio of 5.2:1:5.4. Nutrient uptake is lower during the seedling stage, when growth is relatively slow, and greatest during the flower stalk formation stage. The absorption of nitrogen, phosphorus and potassium differs at each growth stage, so emphasis should be placed on applying organic fertilizer, along with appropriate topdressing.

Seedling Raising Techniques for Gai Lan

1. Sowing time: In the Beijing area, cultivation can basically supply the market year-round. Early-maturing varieties such as Liuye early gai lan are cultivated in the open field to ensure supply from June to October. For sowing from September to March of the following year, mid-maturing and mid-late varieties such as mid-flower and mid-late gai lan can be chosen 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: Gai lan can be direct-seeded or transplanted from seedlings; in the Beijing area, transplanting is mostly used, requiring 75-100 grams of seed per mu. The seedling plot should be sandy loam or loam with convenient drainage and irrigation, 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, they can reach 5 true leaves. Thinning is generally carried out after 2 true leaves appear. Select tender, strong seedlings with good growth, thick stems and relatively large leaf area; do not use small, old seedlings.

Cultivation Techniques for Gai Lan

1. Soil preparation and fertilization: For gai lan cultivation, choose loam that retains fertilizer and water, and prepare the soil 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 the soil, breaking up clods finely. Beds are generally made flat, but for summer cultivation small raised beds should be made.

2. Transplanting method: Open-field cultivation of gai lan should be carried out in the afternoon, while protected cultivation should preferably be done in the morning. After the transplanting date is set, water the seedling bed thoroughly on the afternoon of the day before transplanting so that seedlings can be dug up the next day. On the day of transplanting, dig up the seedlings and immediately transport them to the planting plot, then plant them at a certain row and plant spacing.

3. Planting density: For early-maturing varieties of gai lan, 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. Seedlings should not be planted 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.

4. Watering and fertilization: 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. When entering the flower stalk formation and harvest stages, increase the frequency of watering and keep the soil moist at all times. Base fertilizer and topdressing are equally important; topdressing should be applied with water. Generally, 3-4 days after seedling recovery, apply a small amount of nitrogen fertilizer or diluted chicken manure, and when buds appear and stalks bolt, apply an appropriate quick-acting fertilizer or human manure and urine. After the main stalk is harvested, to promote the growth of side stalks, apply heavy topdressing 2-3 times.

5. Cultivation and hilling: Gai lan 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 goes from thin to thick, being thinner at the base and larger at the top, forming a top-heavy plant, so hilling and fertilizing should be combined with cultivation, preferably applying 1000-2000 kg of organic fertilizer per mu.

6. Pest and disease control: Gai lan has relatively few diseases, with black rot being more commonly seen; 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, and spraying fungicides such as chlorothalonil as soon as diseased spots 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 harvesting: When the flower stalk of gai lan has grown level with or close to the top of the leaves (commonly known as qikou hua, "level-mouth flower"), it is at the suitable harvest stage, and the harvest height is 15-25 cm. To maintain better market quality, harvesting should preferably be done in the early morning, followed by sorting and packing.