A Detailed Guide to Year-Round Cultivation and Management Techniques for Leaf Lettuce (Youmai Cai)

In recent years a new face has appeared on the vegetable market——youmai cai: it looks similar to celtuce, with slender, flat-spreading leaves and a thin, short stem. Youmai cai belongs to a variety of leaf lettuce——long-leaf lettuce, and is similar to the familiar lettuce (shengcai), so it is also called niuli lettuce. The nutritional value of youmai cai is higher than that of lettuce, and far superior to that of celtuce; compared with celtuce, its protein content is 40% higher, carotene 1.4 times higher, calcium 2 times higher, iron 33% higher, and selenium 1.8 times higher. Youmai cai has few insect pests, and basically no pesticides are applied during field production, making it a green vegetable with little pollution.

Youmai cai varieties have strong adaptability, a crisp and fragrant taste, good quality, and a high market price, and are deeply loved by farmers and consumers. The year-round cultivation techniques for youmai cai are summarized below:

I. Variety Characteristics

Youmai cai belongs to the Asteraceae family and is a pointed-leaf type leaf lettuce whose product is the tender shoots and tender leaves. The leaves are long lanceolate, light green in color, with vigorous growth. It has strong disease resistance and adaptability, a crisp and tender texture, and an extremely fresh, tender and fragrant taste. A single plant can reach 0.3 kg, and 667 sq m can yield 3000—5000 kg. It is known as “phoenix tail”.

II. Cultivation Seasons

Youmai cai is heat-tolerant, cold-tolerant and highly adaptable. It can be sown in spring and harvested in summer, sown in summer and harvested in autumn, planted in early autumn and harvested before New Year's Day, and grown in winter greenhouses, etc. For general greenhouse production, it is advisable to grow strong seedlings before the cold winter arrives, that is, the seedling stage should avoid the cold winter season of January. For spring planting, seedlings can be raised in greenhouses in early January; for summer planting, sowing can be done in early April; for autumn planting, sowing can be done in late August.

III. Year-Round Cultivation Techniques 1. Early spring sowing: from January to March, sow and raise seedlings in a medium greenhouse. Build 2 beds in a standard greenhouse, open 1 ditch in the middle, deep-plow and build the beds, water thoroughly to the bottom, broadcast the seeds in the beds, cover with seed soil just enough to cover the seeds, and lay plastic film flat over them (2 layers of film and 1 layer of mulch film). Generally, seedlings emerge in 10-15 days; in cloudy, rainy and low-temperature periods, emergence takes longer. After the seedlings are uniform, remove the mulch film, ventilate and exchange air; during the day, prevent high temperatures from damaging the seedlings, and at night, prevent freezing damage. 2. Summer sowing: from April to June, raise seedlings in the open field. Choose high ground, 2 m including ditches, deep-plow and apply decomposed farmyard manure, build and level the beds. Soak the seeds for 3 hours, and sow after the seeds are air-dried. Water the seedling bed thoroughly to the bottom, broadcast the seeds on the bed surface, cover well with seed soil, and water thoroughly. In case of high temperature and drought, cover the beds with shade netting, and remove the netting in the morning and evening after the seedlings are uniform. The fertilizer and water in the seedling bed should be moderate, and it should not be too dry. 3. Autumn sowing: from July to September, youmai cai seedlings must be soaked and pregerminated. The method is to wrap the seeds in gauze, soak them in water for 3-4 hours, then take them out and place them in the refrigerator compartment for 10-15 hours; sow when 75% have sprouted. For autumn sowing and seedling raising, it is best to use a small arch shed or greenhouse. After emergence, pay attention to soil moisture; it should not be too dry or too wet, and weeds should be pulled out in time to ensure smooth drainage. 

IV. Seedling Raising Techniques

For summer and autumn cultivation of youmai cai, pregermination and sowing are essential, otherwise it is difficult to ensure successful seedling raising. This is because the suitable germination temperature for youmai cai seeds is 15—20°C; above 25°C or below 8°C, they will not germinate. A simple and easy germination method is: first soak the seeds in clean water for 4—6 h, then scoop them out and drain them, put them into silk stockings, and choose one of the following 3 methods for pregermination.

1. River sand pregermination method: spread moist river sand 20—30 cm thick in a cool place, then scatter the soaked seeds on the surface of the river sand, then spread 1—2 cm thick moist river sand, and cover with fresh vegetable leaves.

2. Thermos flask and ice cube pregermination method: hang the soaked seeds inside the flask, add clean water and ice cubes to the flask, and reach 15—20; rinse once every other day and persist in changing the water and adding ice cubes.

3. Refrigerator low-temperature pregermination method: wrap the soaked seeds in gauze, put them in a refrigerator at 15—20°C, and persist in rinsing once every day. The above pregermination takes about 2—4 days, and sowing can be done when 60%-70% have sprouted. In suitable seasons, direct sowing and seedling raising can be used; in winter and spring, heat-preserving seedling raising can be done in arch sheds; in summer and autumn, shade netting is best used for shading and cooling during seedling raising and production.

V. Reasonable Close Planting

Depending on the season, seedling age varies greatly: 20—30 days in summer and autumn, and 50—70 days in winter and spring. Generally, transplanting can be done once there are 4—6 true leaves. The plant and row spacing requirement is 15 cm x 20 cm.

VI. Field Management

Youmai cai is generally cultivated in flat beds. Before transplanting, apply sufficient base fertilizer: for every 667 sq m, apply 5000 kg of high-quality farmyard manure, 40 kg of diammonium, 20 kg of urea, 20 kg of potassium sulfate or 200—300 kg of plant ash. When transplanting, water well with the transplanting water; after 1 week, water thoroughly with the seedling recovery water; after seedling recovery, apply a seedling-promoting fertilizer together with watering (15 kg of urea); in the later stage, heavily apply a plant-promoting fertilizer (30 kg of urea). After transplanting and seedling recovery, cultivate in time and hoe deeply to help the seedlings settle and promote root development. Throughout the entire growth and development period, keep the field moist and the soil loose.

VII. Pest and Disease Control

For downy mildew, use 75% chlorothalonil wettable powder, or 50 g of 58% metalaxyl—mancozeb mixed with 20 kg of water, or 50 g of 70% ethylicin-mancozeb mixed with 15 kg of water, used alternately for better preventive effect: for gray mold and sclerotinia, use 50 g of 50% procymidone powder mixed with 40-50 kg of water for spraying; when the disease is severe, the dosage may be increased as appropriate. The spraying time should preferably be chosen at 3 p.m. on a sunny day or after rain turns clear when the leaf surface has no dew.

VIII. Harvesting

Youmai cai can be eaten at either large or small seedling stages, and the harvesting standard is relatively flexible; it can be harvested from 14—16 leaves. It can be harvested according to market demand. Harvesting too early results in lower yield, while harvesting too late allows the central stalk to bolt, affecting quality. Harvesting is best done in the early morning.