How to Grow American Flag Leeks? Detailed Guide to High-Efficiency Cultivation Techniques

From 2006 to 2007, Dafeng City, Jiangsu Province introduced American Flag leeks, and through two years of cultivation achieved great success, with an average yield of 9850 kg per 667 sq m and a benefit of 8213 yuan. The introduction of this variety greatly boosted the planting benefits of vegetable farmers in the introduction area of Dafeng City and became a new highlight for vegetable farmers in Dafeng City to get rich. Over the two years, through exploration of its cultivation characteristics and cultivation techniques, a relatively practical set of cultivation techniques was summarized. The key points of its supporting cultivation techniques are introduced as follows:

1 Cultivation environment conditions

The American Flag leek has strong adaptability and is not strict about soil requirements. It can be cultivated on sandy soil, loam and clay, but it is most suitable for cultivation on sandy loam rich in organic matter, fertile and loose, with a pH of about 7.7, slightly alkaline soil. The American Flag leek also has relatively broad requirements for climatic conditions and can tolerate a low temperature of -10°C and a high temperature of 38°C, but it grows well under cool and humid climatic conditions, with a suitable growth temperature of 12-25°C. However, the American Flag leek has poor drought tolerance and waterlogging tolerance, so the cultivation site should be selected as fields with high, dry terrain and convenient drainage and irrigation.

2 Seedling raising

2.1 Sowing

2.1.1 Determination of sowing period For open-field seedling raising, sowing can be carried out in batches from March to June. If small arched shed cold-frame seedling raising is used, the sowing period can be advanced to mid-to-late February, with a seedling age of 30-50 d. For autumn sowing, seedlings overwinter, and in the following summer they bolt and flower, and the flower stalks are harvested. In our locality, cultivation mainly harvests spring seedlings raised in small arched sheds.

2.1.2 Seedbed soil preparation Select a plot with fertile soil, good drainage and irrigation, and no previous cropping of onion and garlic crops, and deeply plow and freeze the ridges before winter to mature the soil. 15 d before sowing, deeply plow and harrow the seedling field evenly, apply 3000-4000 kg of decomposed farmyard manure per 667 sq m, mix it evenly with the soil, and make high beds 1.2-1.3 m wide, then sowing can begin.

2.1.3 Seed treatment Be sure to use new seeds of the current year. Before sowing, carefully select the seeds, remove broken seeds and shriveled seeds, and choose plump, disease-free seeds as seed. Sun the seeds for 8-10 h before sowing to help germination. After sunning, place the seeds in 55°C hot water for warm soaking and disinfection for 10 min, then remove them and wait to sow.

2.1.4 Sowing Generally, sow 2-3 kg per 667 sq m of seedbed. When sowing, water thoroughly to the bottom, and after the seedbed soil has sufficient moisture, evenly broadcast the seeds, then cover thinly with a layer of dry fine soil, just enough to cover the seeds. After emergence, add another layer of dry fine soil about 5 mm thick. If using a small arched shed cold frame for seedling raising, set up supports and cover with film promptly after sowing.

2.2 Seedling stage management

2.2.1 Management before emergence For spring sowing and autumn sowing seedling raising, cover with grass or shade netting after sowing for shading, and keep the soil moist regularly.

2.2.2 Management after emergence Seedlings can emerge 1 week after sowing, and full emergence can occur in about 8 days. After full emergence, keep the soil alternately dry and wet, and weed promptly. At the 3-4 leaf stage, when seedlings are 5-6 cm tall, thin the seedlings and spray the leaves once with 1% urea solution. When seedlings are about 12 cm tall, apply 5 kg of urea solution per 667 sq m. When seedlings reach 20 cm tall, transplant them to the field. 5-8 days before transplanting, control water to harden the seedlings, continuously increase the ventilation openings to harden the seedlings, until the shed is completely removed before transplanting.

3 Transplanting

When seedlings are more than 30 cm tall and the false stem is 1 cm thick, choose soil rich in organic matter and loose in texture for transplanting. Before transplanting, harrow finely and level, apply about 4000 kg of decomposed farmyard manure, 20 kg of urea, 50 kg of superphosphate, and 20 kg of potassium sulfate per mu, mix evenly with the soil and harrow finely. Make high beds or high ridges at a row spacing of 60-70 cm, open a ditch 15 cm wide and 10-12 cm deep on them, single row, with a plant spacing of 10-15 cm. After transplanting, water to settle the roots. For ridge cultivation, hill up soil 2-3 times during the growth period.

4 Field management

The temperature suitable for leek growth is 18-22°C during the day and 12-13°C at night. Because leeks are not tolerant of drought or waterlogging, attention should be paid in production to timely watering and drainage. After seedling recovery, water promptly to promote recovery. After rainfall, loosen the soil promptly to prevent crusting. In hot and humid seasons, pay attention to drought resistance and drainage. After autumn begins, water and topdress promptly, applying 10-15 kg of urea per mu combined with watering every 10-15 d. For ridge cultivation, before the rainy season arrives, level the ridges and open ditches to facilitate drainage. During the vigorous growth period, hill up soil once every 10-20 d combined with topdressing, for 2-3 consecutive times, to the extent that the branching point is not buried.

5 Pest and disease control

Common diseases of leeks include downy mildew and gray mold, etc. According to the time and environmental conditions, actively carry out prevention work. When disease occurs, downy mildew can be sprayed for control with 75% chlorothalonil wettable powder at 600 times dilution, and gray mold can be controlled with 50% carbendazim at 600 times dilution. Common pests of leeks include leafminer and onion thrips, which can be controlled with 2% abamectin emulsifiable concentrate at 2000 times dilution.

6 Harvesting and seed saving

Harvesting can begin when seedlings are 30-40 cm tall, and 3-4 harvests can be made in one year. The tools used during harvesting should be clean, hygienic and pollution-free. If seed collection is desired, the autumn sowing seedling raising method should be adopted, with seedlings overwintering, then transplanted to the field in March of the following year, with attention to watering and topdressing. They bolt around mid-May, so water less; during the flower head formation stage and after flowering, increase the amount of watering. Seeds mature in mid-to-late July and should be harvested promptly.