How to Plant the Latest Lettuce Seeds? A Detailed Guide to Planting Methods
Lettuce is native to the Mediterranean coast of Europe and was domesticated from wild species. It has a long history of introduction into China, and is cultivated more extensively along the southeastern coast, especially in the suburbs of major cities and in the Guangdong and Guangxi regions. It has extremely high cultivation value. Common cultivated varieties include Glass Lettuce, Emperor, Caesar, crisphead lettuce, oakleaf lettuce, Dahu 659, and others. Now let us take a look at how to plant lettuce seeds!
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 optimum 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 subzero low temperatures do not greatly hinder growth. The root system is well developed, the leaf surface is waxy, and 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.
How to Plant Lettuce Seeds?
1. Sowing time: Generally, the sowing period for lettuce is from August to February of the following year. The suitable sowing time is from mid-October to mid-December. Sowing is also possible from early March to early July, but the growth period is short and the yield is low. In winter and early spring, cultivate in large or small plastic tunnels; in summer, cultivate under shade netting or a shaded shed. For every 60 sq m of seedling land, apply 1500 kg of decomposed farmyard manure and 20 kg of superphosphate, then plow and mix evenly and level. For seedling raising and transplanting, each mu of cultivation field requires 20-30 sq m of seedbed, with a seed rate of 25-30 grams.
2. Seed germination: When sowing lettuce in the high-temperature season, the seeds must be subjected to low-temperature germination. First soak them in well water for about 6 hours, rub and wash them, then take them out and wrap them in wet gauze. Place them at 15-18°C for germination, or hang them in a water well for germination, or place them in a refrigerator (with the temperature controlled at about 5°C), and after 24 hours place the seeds in a cool place and keep them warm for germination. You can also soak the seeds in a "920" solution at a concentration of 0.2 per thousand for 24 hours, which can smoothly break the dormancy of lettuce seeds, and germination will be complete in 2-3 days. When 80% of the seeds have shown white, sow them in time.
3. Seedling raising and transplanting: Before sowing, water the seedbed thoroughly. Mix the seeds evenly with an equal amount of moist fine sand and broadcast them, then cover with about 0.5 cm of soil. When 2-3 true leaves appear, thin the seedlings in time or divide the seedlings. In winter and spring, when raising seedlings in large plastic tunnels or in the open field, pay attention to keeping the seedbed warm, and at the same time control the amount of watering to prevent excessive humidity. When raising seedlings in the open field in summer, pay attention to covering with shade netting and water 2-3 times a day to keep the soil moist.
Lettuce Planting Management
1. Scientific fertilization: Lettuce requires clay loam rich in organic matter with strong water and fertilizer retention. Lettuce prefers slightly acidic soil, with a suitable 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, among which crisphead lettuce requires more potassium. During the growing period, nitrogen, phosphorus, and potassium fertilizers need to be used in combination. The plot where lettuce is to be planted should be deeply plowed and finely prepared. Before planting, apply sufficient base fertilizer, with 3000-3500 kg of decomposed farmyard manure per mu. After application, plow deeply, water thoroughly to establish the bottom moisture, and make beds after the soil surface dries.
2. Careful planting: The day before planting, irrigate the seedbed so that the seedling blocks are moist. On the second day, lift the seedlings with as much soil as possible to reduce root damage. When planting, first open furrows on the bed surface, with a furrow depth of 4-6 cm. On a 70 cm bed surface, plant 3 rows. After opening the furrows, apply 25 kg per mu of compound fertilizer with three elements, 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 level, cover with plastic film, and guide the seedlings out through the film.
3. Post-planting management: Lettuce likes moisture, and sufficient water supply is required throughout the entire growth period. Water once 5-7 days after planting to help the seedlings recover. After watering to help the seedlings recover, for plots not covered with plastic film, carry out 2 rounds of intertillage, loosening the soil, and weeding. After that, water 3-4 times, and in stages apply nitrogen and phosphorus fertilizers along with watering, at 15-20 kg per mu. Stop watering before harvest to facilitate storage and transport.
4. Disease and pest control: The main diseases of lettuce include downy mildew, soft rot, viral disease, and sclerotinia, among which sclerotinia and soft rot are more harmful. Crop rotation can be adopted, planting density appropriately reduced, and watering should not be excessive. Frequently hoe shallowly to keep the soil surface dry. Remove diseased plants promptly, clear away dead leaves, and burn them in a centralized manner. After the disease occurs, spray agricultural streptomycin and amobam. In hot and humid seasons, spray chlorothalonil once every 5-7 days for prevention. The main pests include aphids, thrips, and cutworms, which can be controlled with omethoate, fenvalerate, and the like.