Greenhouse lettuce planting method and time

Lettuce is a vegetable of the genus Lactuca in the Asteraceae family. It is widely grown and eaten around the world and comes in many varieties, including green leaf lettuce, romaine lettuce, butter lettuce, Boston lettuce, etc., each with its own unique flavor and texture. Let’s learn about the planting methods and time of greenhouse lettuce.

1. Variety selection

You can choose the "American Large Fast-Growing" variety. Other varieties can also be selected. The plant of this variety is in a semi-upright state, with emerald green leaves that are wrinkled and loose on the surface. The plant is about 25 cm tall, about 30 cm wide, and weighs about 300 grams per plant. It has good disease resistance and cold tolerance, is not prone to bolting, and has a wide adaptability.

2. Planting seeds

In early to mid-October, sowing is carried out when the temperature is between 10 and 20 degrees Celsius. The optimal germination temperature for lettuce seeds is 15~20℃. It is difficult to germinate when the temperature exceeds 25℃ or is lower than 8℃. Dig furrows on the flat bed surface with a depth of about 2 cm and a row spacing of 35 cm. Then sow seeds evenly along the furrows. The seed dosage is 60 g/667 square meters.

3. Management after sowing

Water immediately after sowing, and then water a second time about 10 days later depending on weather conditions. Winter irrigation should be carried out before frost in mid-November when the lettuce has 4 to 5 true leaves. Then cover the shed with a double layer of film, compact the soil around the film, and seal the exit of the greenhouse. There is no need for heating throughout the winter, just clear the snow on the roof regularly to protect the greenhouse film.

4. Spring Management

4.1 Tillage, thinning and irrigation

In late February of the following year, after the temperature rises, inter-cultivation should be carried out in time to weed and promote root growth. When the lettuce has grown to 5 to 6 true leaves, thin out the seedlings once, keeping the plant spacing at 30 to 35 cm. Subsequently, the seedlings are thinned out, which helps to form a good root system, make the leaves thick and green, and the plants strong, laying the foundation for later growth and high-quality output. After about 10 days of seedling stage, start watering and fertilizing to keep the soil moist. On the basis of applying organic fertilizer , apply a small amount of nitrogen fertilizer with water twice, 5 to 10 kg/667 square meters each time. Stop watering and fertilizing about 7 days before harvest.

4.2 Disease control

The main threats facing lettuce are downy mildew and cabbage loopers. Biological control methods for downy mildew include controlling the temperature in the greenhouse, timely ventilation and heat dissipation, inter-cultivation after watering, and avoiding heavy flooding in the late growth stage. For chemical control, you can use 500-800 times diluted 75% thiophanate-methyl wettable powder or 500-700 times diluted 65% mancozeb wettable powder for spraying at the early stage of the disease, once every 7-10 days, and spray 2-3 times in a row.

For biological control of cabbage loopers, weeds and field residues should be removed in a timely manner, and the soil should be deep-turned to effectively reduce the insect population density. When using pesticides for control, spraying should be carried out before the larvae reach the third stage, using 2.5% Kung Fu 20~30 ml/667 square meters for control.

The above is an introduction to the key points of greenhouse lettuce cultivation . The greenhouse model can ensure the supply of lettuce all year round, and high yields can be achieved if the method is mastered.