When is the latest planting time for celtuce?

The planting time for celtuce needs to be determined according to local climate conditions, variety characteristics, facility conditions, and the annual cropping schedule, so as to set a suitable planting time for celtuce. In the Yangtze River Basin, celtuce is overwintered in the open field, mainly as spring celtuce, generally sown in autumn of the first year from September to October, and transplanted after 40-50 days when the seedlings have 5-6 true leaves. It can overwinter safely in winter, and after greening up the following spring there is sufficient time for the leaf rosette to grow, so a high yield can be obtained when harvested from April to May.

Growing environment for celtuce

1. Celtuce is a semi-cold-tolerant vegetable. It prefers cool conditions, tolerates light frost, fears high temperatures, and grows poorly in hot seasons.

2. Celtuce is a long-day crop and needs sufficient light; it is sensitive to soil acidity and alkalinity and is suitable for growing in slightly acidic soil.

3. Celtuce has a shallow root system and weak absorption capacity, and has a relatively high demand for oxygen. Sandy loam and loam are best for growing celtuce.

Field management for celtuce cultivation

Spring lettuce overwinters as seedlings. Its early growth is slow and its fertilizer requirement is low. After planting, water once with diluted manure water. If base fertilizer cannot be applied because of intercropping or relay cropping, 1-2 additional applications of manure should be made during the year, at 1000-1500 kg per mu, combined with intertillage and soil loosening to promote root growth. Before winter, fertilizer and water should be controlled to avoid excessive vegetative growth, enhance cold tolerance, and ensure safe overwintering. After the beginning of spring, stems and leaves grow rapidly. After entering the rosette stage, cultivate and loosen the soil in time to raise soil temperature, and apply one topdressing, at 1000 kg per mu of 30% human manure and urine. After the plants close the rows, stem thickening accelerates and the fertilizer requirement becomes greater. Apply 2-3 heavy topdressings, totaling 2000-3000 kg of human manure and urine or 30-40 kg of urea, to ensure stem expansion. Fertilization must not be too late, so as to avoid stem cracking.

1. Select good seed, germinate at low temperature, and cultivate strong seedlings. Choose high-yielding varieties with strong heat tolerance, weak response to daylength, and resistance to bolting, such as the particularly heat-tolerant Erbaipi celtuce. Sow and raise seedlings in late June, and choose a seedbed in a high, dry, and fertile location. Soak the seeds before sowing to promote germination. The method is to soak the seeds in clean water for 24 hours, remove and wash them, wrap them in gauze, and place them in a refrigerator. After treatment at -3 deg C to -5 deg C for 24 hours, put the seeds that have formed ice blocks indoors in a cool place and let them gradually thaw. After 3-5 days, when 80% of the seeds have sprouted, they can be sown. The soaked seeds can also be hung in a well 30 cm above the water surface to promote germination. After the seeds sprout, mix in a small amount of fine sand and sow evenly, at 2-3 g per square meter. After sowing, cover lightly with fine nutrient soil, spread a shade net flat over the bed surface, and water thoroughly. Cover the small arch frame above the bed with a shade net and agricultural film to shade, retain moisture, and promote emergence. After emergence, remove the surface shade net and scatter dry fine soil to stabilize the seedlings; on the frame, cover with a shade net after 8 a.m. on sunny days and uncover it after 5 p.m.; do not cover on cloudy days, and promptly cover with a shade net and agricultural film during heavy rain; after 2 true leaves, gradually reduce the covering time. During the seedling stage, pay attention to controlling underground pests and snails. Transplant the seedlings at 22-25 days of age.

2. Reasonable close planting, shading, and moisture retention. In mid-to-late July, after the lettuce seedlings have 4-5 true leaves unfolded, choose the evening or a cloudy day to transplant with soil, generally with a row spacing of 33 cm and a plant spacing of 30 cm. Pay attention to grading and transplanting large and small seedlings separately. After transplanting, water thoroughly to establish the plants, and cover the greenhouse frame with a shade net to promote seedling recovery.

3. Apply sufficient base fertilizer and topdress in time. Lettuce takes a little more than one month from transplanting to harvest. If fertilizer is lacking, the plants will grow poorly and are prone to premature bolting, reducing yield and quality, so the base fertilizer must be sufficient. Generally apply 2500-3000 kg of decomposed human and livestock manure per mu, or 1000 kg of decomposed chicken manure, and 25-30 kg of 45% nitrogen-phosphorus-potassium compound fertilizer, then plow, level the land, and make beds. After the lettuce resumes growth and establishes, apply 1-2 light manure water applications as appropriate to promote seedling growth. After the rosette stage, when the fleshy stem begins to expand, apply 15-20 kg of urea per mu with irrigation.

4. Harvest at the right time. When the heart leaves of the lettuce are level with the tip of the highest leaf, it can be harvested for market. The general yield per mu is 1800-2000 kg, with an income of about 3000 yuan.

Disease control in celtuce cultivation

Celtuce mainly suffers from downy mildew, sclerotinia rot, viral disease, and gray mold. Prevention should be the main approach. Under the suitable temperatures for lettuce growth (not exceeding 24 degrees during the day and not lower than 10 degrees at night), increase ventilation as much as possible. When humidity is on the high side, timely ventilation to dissipate moisture can prevent disease occurrence. Once disease occurs, use medication promptly according to the condition to prevent it from spreading.

1. Downy mildew: spray with 2000-2500 times diluted Yikuaijing solution, or spray with 2500 times diluted Anke solution.

2. Sclerotinia rot: spray with 1000 times diluted Sukeling solution, or spray with 1000 times diluted Nongliling solution.

3. Viral disease: spray with 500 times diluted Bingdu A solution, or spray with 1000 times diluted Junkeduke solution.

4. Gray mold: spray with 800 times diluted Shijiale solution, or spray with 600-800 times diluted Fumeili solution.