Detailed Explanation of Key Lettuce Cultivation and Management Techniques

Lettuce is one of the vegetables commonly eaten in daily life. Its appearance is somewhat similar to celtuce, though it is a miniature version. Lettuce tastes very refreshing; whether served cold, stir-fried, or cooked in a hot pot, it has its own distinctive flavor. Below, let us take a look at the introduction to lettuce cultivation and management techniques.

1. Sowing time for lettuce

Lettuce prefers a cool climate, so sowing is generally carried out in spring and autumn. In spring, sowing usually begins from February to April, and harvest can be done from May to June. For autumn sowing, sowing can begin at the end of August, and harvest can be done from September to October. Because different varieties of lettuce have different characteristics, when choosing the sowing time, first read the instructions for the lettuce seeds you have bought, and then sow according to the sowing times above. Spring and summer are suitable for sowing loose-leaf lettuce (such as butterhead lettuce and colored-leaf lettuce), which is more heat-tolerant. Autumn and winter are suitable for sowing head lettuce (also called iceberg lettuce), which is not heat-tolerant.

2. Fertilizing and land preparation

Before land preparation, clear away the remaining branches, leaves, roots, and plastic film from the previous crop. Apply 5000-6000 kg of decomposed organic fertilizer per mu, 50 kg of three-element compound fertilizer, and 50 kg of quicklime, spread them evenly, deep-plow 20 cm, harrow finely and level, and make beds. For cultivating head lettuce, ridges need to be formed and covered with plastic film.

3. Transplanting

Before lifting seedlings for transplanting, water the seedlings first to moisten the seedbed so that soil blocks are carried when the seedlings are lifted. When lifting seedlings, carry as much soil as possible and damage the roots as little as possible. For transplanting, determine the plant and row spacing according to variety requirements. The transplanting depth should be such that the soil block around the roots is buried level. Firmly fill the transplanting holes with soil around them so that the seedling root blocks are in close contact with the soil. Water immediately after transplanting. After the ground surface is slightly dry, shallow hoe once in time to help preserve soil moisture and raise soil temperature.

When transplanting, pay attention to the weather conditions. Do not plant on overcast days, when cold air is arriving, or on rainy or snowy days. Wait until the weather improves before planting. In winter, plant on sunny mornings; in summer, plant in the afternoon or near sunset to prevent high summer temperatures from scalding the seedling leaves.

4. Management after transplanting

After transplanting and before the seedlings recover, the air humidity and temperature in the greenhouse can be slightly higher, with daytime temperatures of 20℃-25℃ and nighttime temperatures of 10℃-15℃. After the seedlings recover, the temperature can be lowered appropriately, with daytime temperatures of 18℃-22℃ and nighttime temperatures of 10℃-15℃. During the harvest period, in order to delay the supply time, control the daytime temperature at 15℃ and the nighttime temperature at 5℃-10℃.

For loose-leaf lettuce, about 10-15 days after transplanting and seedling recovery, apply topdressing together with watering, applying 10 kg of urea per mu. After topdressing and watering, weed and loosen the soil in time to prevent soil compaction and maintain soil aeration. Afterwards, depending on growth conditions and weather conditions, carry out topdressing and watering at the appropriate time, keep the soil alternately dry and moist, strengthen ventilation, and control air humidity to avoid disease occurrence.

For head lettuce, topdressing and watering after seedling recovery are the same as for loose-leaf lettuce. When the heart leaves begin to fold inward, topdress with three-element compound fertilizer, applying 15-20 kg per mu, together with watering. Afterwards, carry out topdressing and watering according to growth conditions, mainly using three-element compound fertilizer and appropriately combined with water-soluble fertilizer. After each watering, be sure to weed and loosen the soil to maintain soil aeration. Stop watering 5 days before harvest to avoid disease occurrence.

5. Pest and disease control

In greenhouse cultivation of lettuce, the main diseases that occur are lettuce downy mildew, lettuce brown rot, and lettuce soft rot.