How to Grow Lettuce: The Latest Planting Techniques and Methods Tutorial

Lettuce is the common name for leaf lettuce, also known as goose lettuce, mai tsai, wo tsai, etc. It is an annual or biennial herbaceous crop of the genus Lactuca in the Asteraceae family, native to the Mediterranean coast of Europe, domesticated from wild species. It has a long history of introduction into China, and is cultivated more extensively in the southeastern coastal areas, especially in the suburbs of major cities and the Guangdong and Guangxi regions. It has extremely high cultivation value. Let us take a look at lettuce planting techniques below!

Growth Habits of Lettuce

Lettuce prefers a cool environment; it is neither cold-tolerant nor heat-tolerant. The suitable growing temperature is 15-20°C, and the growth period is 90-100 days. The seeds are relatively tolerant of low temperatures and can germinate at 4°C; the optimal germination temperature is 18-22°C, and they hardly germinate above 30°C. During the growing period, it prefers a cool climate, growing best at 15-20°C with high yield and excellent quality. Growth is poorer when the temperature remains above 25°C, but it is also quite cold-tolerant, and 0°C or even short periods of sub-zero low temperatures do not greatly hinder its growth. The root system is well developed, the leaf surface has a waxy coating, and its drought tolerance is quite strong. However, when cultivated in fertile, moist soil, the yield is high and the quality is good. The suitable soil pH is 5.8-6.6.

Variety Selection for Lettuce

1. Crisphead lettuce: The main characteristic of crisphead lettuce is that the terminal leaves form a head. The leaves are entire, serrated, or deeply lobed; the leaf surface is smooth or wrinkled; and the terminal leaves form a round or nearly round head. The main varieties include Dahua 659, Qianwei 75, Salinas, Beishan No. 3, Mamik, Bilu, and others.

2. Curly-leaf lettuce: The main characteristic of curly-leaf lettuce is that it does not form a head. The basal leaves are long ovate, with relatively long petioles; the leaf margins are wavy with notches or deep lobes; and the leaf surface is wrinkled. The clustered leaf rosette resembles a large flower. The main varieties include “Red Sail” purple-leaf lettuce, red flower-leaf lettuce, Lubo, Dongshan lettuce, and others.

3. Upright lettuce: The main characteristic of upright lettuce is that the leaves are narrow and long, growing upright. The leaves are entire or serrated, thick, with relatively coarse texture and poorer flavor. There are fewer variants, its distribution area is not wide, and it is rarely cultivated in China.

Seedling Raising Techniques for Lettuce

1. Select good seeds for sowing: Choose suitable varieties according to need, such as Glass Lettuce, Emperor, Caesar, crisphead lettuce, spotted-leaf lettuce, Dahu 659, and others.

2. Prepare the seedbed: For raising lettuce seedlings, it is advisable to choose fertile sandy loam with good water and fertilizer retention. Seedbed soil preparation: For a 10 sq m seedbed, use 10 kg of decomposed organic fertilizer, 0.3 kg of ammonium sulfate, 0.5 kg of superphosphate, and 0.2 kg of potassium sulfate. Mix thoroughly, spread evenly, and rake fine. Water sufficiently to saturate the bottom, and sow after the water has seeped in.

3. Sowing and seedling raising: To ensure even broadcasting, a small amount of fine sandy soil can be mixed into the seeds when sowing. After sowing, cover with 0.3-0.5 cm of moist soil and cover with plastic film to retain moisture. The sowing rate is 30-50 grams per mu. When the seedlings begin to emerge, promptly uncover the plastic film on the bed surface to prevent leggy growth. The seedbed temperature should preferably be controlled at 18°C-20°C during the day and 12°C-14°C at night. Pay attention to ventilation, and provide shade in case of strong sunlight. When the seedlings grow to 2-3 true leaves, transplant them at a spacing of 6-8 cm between plants and rows. When they grow to 4-5 true leaves, they can be planted out. During the seedling stage, generally do not water unless there is a lack of water.

Planting Management of Lettuce

1. Scientific fertilization: Lettuce requires clay loam rich in organic matter with strong water and fertilizer retention. Lettuce prefers slightly acidic soil, with an optimal soil pH of 5-7. For every 1000 kg of lettuce produced, it needs to absorb 2.5 kg of nitrogen, 1.2 kg of phosphorus, and 4.5 kg of potassium, with crisphead lettuce requiring more potassium. During the growing period, nitrogen, phosphorus, and potassium fertilizers need to be used in combination. The plot for planting lettuce should be deeply plowed and carefully prepared. Before planting, apply sufficient base fertilizer, 3000-3500 kg of decomposed farmyard manure per mu. After application, plow deeply, water sufficiently to saturate the bottom, and make beds after the soil dries.

2. Careful planting: The day before planting, irrigate the seedbed to moisten the seedling blocks. The next day, lift the seedlings with as much soil as possible to reduce root damage. When planting, first open furrows on the bed surface, 4-6 cm deep, and plant 3 rows on a 70 cm bed. After opening the furrows, apply 25 kg per mu of NPK compound fertilizer and then irrigate. After the water seeps in, place the seedlings at a spacing of 24 cm, cover with soil, and close the furrows. Rake the bed surface flat, cover with plastic film, and guide the seedlings out through the film.

3. Post-planting management: Lettuce prefers moisture and requires a sufficient water supply throughout the growing period. Water once 5-7 days after planting to help the seedlings recover. After watering for seedling recovery, carry out 2 rounds of intertillage, loosening, and weeding on plots not covered with plastic film. Thereafter, water 3-4 times, and apply nitrogen and phosphorus fertilizers in stages along with watering, at 15-20 kg per mu. Stop watering before harvest to facilitate storage and transport.

4. Pest and disease control: The main diseases of lettuce include downy mildew, soft rot, viral disease, and sclerotinia, among which sclerotinia and soft rot are more harmful. Measures can include crop rotation, appropriately reducing planting density, not watering excessively, frequently shallow hoeing and raking, keeping the soil surface dry, promptly removing diseased plants, clearing withered leaves and burning them in a centralized manner. After disease onset, agricultural streptomycin and amobam can be sprayed. In hot and humid seasons, spraying chlorothalonil once every 5-7 days serves as a preventive measure. The main pests include aphids, thrips, and cutworms, which can be controlled with omethoate, fenvalerate, and similar agents.

5. Scientific harvesting: Non-heading lettuce can be harvested at the appropriate time according to market prices. For crisphead lettuce, it is best to harvest after the head is firm. Harvesting too early will affect yield, while harvesting too late will cause the inner stem of the head to elongate, the head to become loose, and quality to decline.