A Detailed Guide to Lettuce Planting Techniques and Management Methods

1. Climate Conditions

Lettuce prefers a cool climate. The minimum temperature for seed germination is 4°C, and germination takes a long time. The optimum temperature for germination is 15-20°C, with germination in 3-4 days, while temperatures above 30°C hinder germination. Therefore, when sowing in summer, low-temperature treatment is necessary to promote enzyme activity within the seeds and the conversion of other substances. The optimum temperature for stem and leaf growth of head lettuce is 11-18°C, and the optimum temperature during the heading stage is 17-18°C. Seedlings can tolerate low temperatures of -5°C. Above 21°C, heads are difficult to form, or the excessive internal temperature of the head causes the heart leaves to necrose and rot. When temperatures exceed 30°C, growth is poor. The temperature adaptation range of non-heading lettuce is broader than that of head lettuce. Regarding sensitivity to daylength response, early-maturing varieties are the most sensitive, mid-maturing varieties are next, and late-maturing varieties respond sluggishly.

2. Soil Conditions

Lettuce is suited to slightly acidic soil. When planted in soil rich in organic matter, it has strong water and fertilizer retention and high yields. If planted in dry, water-deficient soil, the root system develops incompletely, growth is not substantial, the vegetable tastes slightly bitter, and the quality is poor.

3. Moisture Conditions

Lettuce has different water requirements at different growth stages. During the seedling stage, it must not be too dry or too wet; if too dry, the seedlings tend to age, and if too wet, the seedlings tend to grow leggy. During the rosette stage, water should be controlled appropriately. During the heading stage, water must be sufficient; a shortage of water results in small leaves and a bitter taste. In the late heading stage, water should not be excessive, to avoid head cracking, which can lead to disease.