When is the latest time to grow lettuce?

The planting time of lettuce needs to be determined according to the local climatic conditions, variety characteristics, facility conditions and the arrangement of planting stubble throughout the year. Lettuce in the Yangtze River basin overwinters in the open field, mainly spring lettuce, which is generally sown from September to October in the first year, and when the seedlings are planted with 5-6 true leaves in 40-50 days, they can survive the winter safely and have sufficient time to grow leaves after turning green in the second spring, and a high yield can be obtained after harvest from April to May.

The planting environment of lettuce

1, lettuce is a semi-cold-tolerant vegetable, like cold, slightly resistant to frost, afraid of high temperature, poor growth in hot season.

2. Lettuce is a long-day crop with sufficient light, and it is sensitive to soil acidity and alkalinity, so it is suitable to be planted in slightly acidic soil.

3. The root system of lettuce is shallow, the absorption capacity is weak, and the demand for oxygen is high. Sand loam and loam are the best soil for planting lettuce.

Field management of lettuce planting

Spring lettuce overwintered with seedlings, grew slowly in the early stage, needed less fertilizer, and watered once after planting. If intercropping could not apply base fertilizer, it should be applied 1-2 times as manure per mu, 1000-1500 kg per mu, combined with ploughing and thinning soil to promote root growth. It is necessary to control fertilizer and water before winter, avoid overgrowth, enhance cold resistance and pass the winter safely. After the beginning of spring, the stems and leaves grow rapidly, and after entering the rosette stage, ploughing and loosening the soil in time, raising the soil temperature, combined with topdressing, 1000 kg of manure is applied per mu. After the closure of the plant, the stem hypertrophy accelerated, requiring more fertilizer, re-application of 2-3 times of topdressing, a total of 2000-3000 kg of human feces and urine or 30-40 kg of urea to ensure stem expansion. Fertilizer should not be applied too late, so as not to cause stem cracking.

1. Select improved varieties, accelerate sprouting at low temperature, and cultivate strong seedlings. Select high-yield varieties with strong heat tolerance, slow response to sunlight and not easy to bolting, such as extra heat-resistant two-white-skinned lettuce. Sowing and raising seedlings in late June, the seedbed is chosen in a place with high dry terrain and fertile soil. Soak seeds before sowing to promote sprouting to facilitate seedling emergence. The method is to soak the seeds in clean water for 24 hours, remove and wash them, wrap them with gauze and place them in the refrigerator. After-3 ℃ to-5 ℃ treatment for 24 hours, put the frozen seeds in a cool indoor place and let them melt gradually. After 3-5 days, 80% of the seeds can be sown. Soaked seeds can also be hoisted to the well 30 centimeters above the surface of the water to accelerate germination. Seeds are sown evenly with a small amount of fine sand after budding, sowing 2-3 grams per square meter. After sowing, the nutritious fine soil is covered shallowly, and the border surface is covered with a sunshade net to make up the bottom water. The small arch shed above the border is covered with sunshade net and agricultural film, shading and moisturizing to promote seedling emergence. After emergence, remove the surface sunshade net and sprinkle dry fine soil to stabilize the seedlings; the sunshade net on the scaffolding is covered after 8 am and 5 pm on a sunny day; the sunshade net and agricultural film are covered in time for cloudy days and heavy rain; the covering time is gradually reduced after 2 true leaves, and attention should be paid to the control of underground pests and snails at the seedling stage. Seedlings were transplanted at the age of 22-25 days.

2. Reasonable close planting, shading and moisturizing. Lettuce seedlings in mid-late July after 4-5 true leaves spread, choose evening or cloudy days with soil transplanting, generally row spacing of 33 cm, plant spacing of 30 cm. Pay attention to the graded transplanting of large and small seedlings, pour enough water after planting, and cover the sunshade net on the greenhouse to promote the slow seedling.

3. Apply enough base fertilizer and topdressing in time. Lettuce from planting to harvest for more than a month, if lack of fertilizer, the plant will grow poorly, prone to early bolting, yield and quality decline, so the base fertilizer should be sufficient. Generally, 2500-3000 kg of mature human and animal manure, 1000 kg of rotten chicken manure, and 25-30 kg of nitrogen, phosphorus and potassium compound fertilizer are applied per mu to plough and prepare the land to make beds. After waking up, lettuce should be applied 1-2 times of dilute manure fertilizer to promote seedling growth. When the fleshy stem began to expand after the rosette stage, combined with watering, 15-20 kg urea per mu was applied.

4. harvest at the right time. When the tip of the heart leaf of lettuce is the same as that of the highest leaf, it can be harvested and listed on the market. Generally, the yield per mu is 1800-2000 kg, and the income is about 3000 yuan.

Disease control of lettuce planting

Lettuce mainly has downy mildew, Sclerotinia sclerotiorum, virus disease, gray mildew, mainly to prevent, in order to meet the appropriate temperature for the growth of lettuce (no more than 24 degrees during the day, not less than 10 degrees at night), increase ventilation as far as possible, in the case of high humidity, timely ventilation and humidity can prevent the occurrence of diseases, once the disease occurs, timely use of medicine according to the disease to prevent the spread of the disease.

1. Downy mildew: Yikuangjing 200000x liquid spray, Anke 2500 times liquid spray.

2. Sclerotinia sclerotiorum: Sclerotinia sclerotiorum 1000 times liquid spray, Nongliling 1000 times liquid spray.

3. Virus disease: virus A500 times liquid spray, JK duke 1000 times liquid spray.

4. Botrytis cinerea: Shijiale 800 times liquid spray, Pythium 600 times 800 times liquid spray.