What causes lettuce to turn red? Lettuce growing conditions

Lettuce is one of the most common vegetables in our daily life. It is also eaten very frequently. It is both convenient and healthy for people. Today we will take a deeper look at lettuce, its specific growing conditions, planting methods, growth environment, etc., and learn about another aspect of lettuce.

Contents of this article

1. Why does lettuce turn red?

2. Lettuce growing conditions

3. Lettuce planting method

Why does lettuce turn red?

If you find that the root of the lettuce or the edge of the leaves have turned red, it means that the iron in the lettuce has been oxidized, which means it is not fresh. Chlorophyll is easily degraded, and after degradation, lutein, carotene, carotenoids, etc. become relatively more. Lettuce will "turn" red after being left for a long time.

Lettuce Growing Conditions

Lettuce likes cool climates, and the optimum growth temperature is 15-20℃. It is most suitable for an environment with a large temperature difference between day and night and a low temperature at night. The optimum temperature for head formation is 10-16℃. If the temperature exceeds 25℃, the heart leaves will rot and grow poorly due to the high temperature inside the head. The germination temperature of seeds is 15-20℃. If it is higher than 25℃, the seed coat will be blocked from absorbing water and the germination will be poor. Lettuce needs to be treated at low temperature when sowing in summer. After soaking the seeds, put them in the refrigerator to germinate. Sow them after the buds turn white. Apply a new lipid film to mix the seeds before sowing. Loose-leaf lettuce is more heat-resistant, but it also grows poorly in high temperature seasons. Lettuce likes slightly acidic soil (pH6-6.3 is best), and sandy loam or clay loam with strong water retention and good drainage is preferred. Lettuce needs more nitrogen fertilizer, so organic fertilizer should be applied as base fertilizer before planting, and no organic fertilizer should be applied during the growth process. Water cannot be lacking during the growth period, especially during the head-forming period of head lettuce, which requires sufficient water. If there is a lack of water early, not only will the head be small, but the leaves will taste bitter and have poor quality. However, there should not be too much water, otherwise the head will fall apart, affecting the appearance quality, and easily leading to the occurrence of soft rot and sclerotinia. Only with proper water and fertilizer management and timely spraying of Zhuangjingling during the growth stage can high-yield and high-quality lettuce be obtained.

Lettuce Planting Method

1. Sowing: Usually seedlings are raised first. Lettuce seeds are too small and too light, so they need to be mixed with fine sand. Place them in a container and stir evenly. Then sprinkle them on the soil and cover them with 0.5 to 1 cm of soil, a thin layer. They will germinate in about 3 to 5 days at 15 to 20 degrees. When the temperature is higher than 25 degrees, they are difficult to germinate. When planting in summer, they need to be germinated. Soak the seeds for 1 night, then wrap them with wet gauze and put them in the refrigerator (about 5 degrees). When more than half of the seeds are white, they can be sown.

2. Seedling stage: Keep the soil moist, not dry, and keep the soil permeable. Thin out when there are 2 to 3 true leaves, with a spacing of 5 to 8 cm.

3. Transplanting: Transplant the seedlings when they grow 5-6 true leaves. Water thoroughly before transplanting, and move them to a large pot with the soil on the roots. The spacing between loose-leaf lettuce plants is 15 cm, and the fruiting plant is 30 cm. Water thoroughly, and place them in a cool place in summer to slow down the growth. After about a week, the roots have established themselves, and they can be exposed to normal sunlight.

4. Fertilization: Fertilize once a week after transplanting (nitrogen fertilizer is the best, decomposed organic fertilizer is the best), and apply organic fertilizer or compound fertilizer mainly composed of nitrogen, phosphorus and potassium once in 2 weeks and 4 weeks after transplanting. Stop fertilizing 2 weeks before harvesting.

5. Watering: Water in the morning and evening when the temperature is high. It is better to water in small amounts frequently, but avoid waterlogging. It is suitable to control water in the early stage of growth and keep it moist.