What are the key points of lettuce cultivation techniques?

Lettuce is a vegetable that has risen in popularity in recent years. When people talk about lettuce, some will certainly think it is the tender leaves of celtuce, but this is not the case. Although lettuce looks like celtuce, it actually belongs to the broad category of romaine lettuce. As market demand for lettuce increases, the number of people growing lettuce is also gradually increasing.

Lettuce Cultivation Techniques

1. Variety Characteristics

Plant height 30-40cm, spread 20-30cm, leaves lanceolate, about 40cm long, 6-10cm wide, green, smooth leaf surface, cold-resistant, heat-tolerant, bolting-resistant, highly adaptable, can be cultivated year-round in open fields and protected cultivation, seeding rate per mu is 30-40g.

2. Timely Sowing

Lettuce is heat-tolerant, cold-tolerant and highly adaptable. It can be spring-planted and summer-harvested, summer-planted and autumn-harvested, early autumn-planted and harvested before New Year's Day, as well as winter greenhouse production, etc. Generally for greenhouse production, it is best to grow strong seedlings before the cold winter arrives, that is, the seedling stage should avoid the cold winter season of January. Spring planting can be raised as seedlings in late January, summer planting can be sown in early April, and autumn planting can be sown in late August.

3. Sowing and Seedling Raising

It is required to select seeds that are fresh in color and plump, and to do a good job of pre-sowing treatment. Turn and sun-dry the seeds, accelerate germination, and the seeding rate per mu is 0.1-0.12 kg.

After sowing, cover the seeds with fine soil, with the fine soil layer about 1 cm thick, and water to keep moist. 3-10 days after sowing, the seedlings emerge. When the seedlings grow to 2-3 true leaves, thinning should be carried out. Thinning should be done on sunny and warm days, and water should be applied promptly to protect the seedlings.

4. Land Preparation

The selection of seedling land requires loose soil, good air permeability, and sandy loam soil that can retain water and fertilizer. After the seedling land is loosened and sun-bleached white, prepare the land and make beds at 1.2-1.5 m including trenches, with a bed height of 25 cm, and the bed surface soil should be fine and uniform. The seedling land should be applied with sufficient base fertilizer, mainly decomposed organic fertilizer, and the base fertilizer should be fully mixed with the seedling land soil before sowing.

5. Transplanting and Field Planting

For the field where lettuce is grown, it is required to select sandy loam soil with convenient drainage and irrigation and a neutral or slightly acidic soil pH. After the field is applied with sufficient base fertilizer, plow and harrow to prepare the land. Make beds 1.5 m wide (including trenches). After making the beds, open horizontal rows for planting, with a spacing of 3×4 cun. When the seedlings grow to 4-5 true leaves, they can be transplanted and field-planted, with 3500-4000 plants per mu. After transplanting, water thoroughly to settle the roots.

6. Field Management

Lettuce is generally cultivated in flat beds. Before field planting, apply sufficient base fertilizer: per 667 sq m, apply 5000 kg of high-quality decomposed barnyard manure, 40 kg of diammonium phosphate, 20 kg of urea, 20 kg of potassium sulfate or 200-300 kg of plant ash. When field planting, water well with planting water; after 1 week, water thoroughly with seedling revival water; after seedling revival, along with watering, apply seedling-promoting fertilizer (per 667 sq m use 15 kg of urea); in the later stage, heavily apply plant-promoting fertilizer (per 667 sq m use 30 kg of urea). After field planting and seedling revival, timely carry out intertillage and deep hoeing to help control excessive growth and promote root development. Throughout the entire growth and development period, keep the field moist and the soil loose.

7. Timely Harvesting

The harvest of lettuce should be done at the right time. When it grows to 10-12 leaves, it is the most suitable harvest period; harvesting at this time gives the best quality.

Lettuce Growth Habits

Lettuce seeds do not have high requirements for germination conditions. Generally, they can germinate smoothly above 4℃. If the temperature is between 15-20℃, lettuce seeds can germinate in only 3-4 days. If the temperature exceeds 30℃, lettuce seeds will not germinate. The most suitable temperature for the lettuce seedling stage is 12-20℃. If the daytime temperature exceeds 24℃ and the nighttime temperature is also above 19℃, it is very easy to cause premature bolting of lettuce.

Water and Fertilizer Management for Lettuce

1. Water Management

After lettuce is transplanted, water promptly with planting water. Then according to actual weather conditions, water once with seedling revival water after about 3-5 days. In the early stage of lettuce growth, since the rows have not closed, the field soil is exposed, and water dissipates relatively quickly, so water should be supplemented promptly to prevent drought. In the peak growth period of lettuce, as the leaves increase and leaf area expands, field water evaporation increases. To ensure normal growth of lettuce, sufficient water must be provided. Generally, water once a day, and watering should be done in the morning or evening; if the weather is too dry, water once in the morning and once in the evening. Flood irrigation should not be used when watering, and there should be no standing water in the field.

2. Fertilizer Management

About 10 days after field planting, lettuce can be appropriately topdressed. Fertilization should be frequent, and the fertilizer concentration should not be too high. Decomposed manure water and urine water are best. On the basis of applying organic fertilizer, a small amount of nitrogen fertilizer can be topdressed with water, 2-3 times, applying 5-10 kg each time per mu. At the same time, about 10 days after field planting, foliar fertilizer can be sprayed once, using a mixed solution of 0.3% potassium dihydrogen phosphate and urea. During the entire growth period, foliar fertilizer can be sprayed 3-4 times, once every 7-10 days. About 5 days before harvest, it is best not to water or fertilize anymore, so that the plants are not too tender, reducing plant water content and improving quality.

Pest and Disease Control Methods for Lettuce

For lettuce downy mildew, use 75% chlorothalonil wettable powder, or 50g of 58% metalaxyl-mancozeb mixed with 20kg of water and 50g of 70% ethirimol-mancozeb mixed with 15kg of water alternately; the preventive effect is better. For lettuce gray mold, sclerotinia rot and brown spot, use 50g of 50% procymidone powder mixed with 40-50kg of water for spraying. When the disease is severe, the dosage may be increased as appropriate. The spraying time should preferably be chosen at 3 p.m. on a sunny day or when the leaves are free of dew after rain clears.

Whether lettuce is grown for one's own consumption or sold to a broader market, the quality of lettuce is very important. Therefore, the care of lettuce during the growing process is crucial. When growing lettuce, not only should the timing of planting be grasped well, but also water and fertilizer management and pest and disease control should be done well.