Lettuce is a cultivar of the genus Lettuce in the family Asteraceae that feeds on young leaves. Native to the Mediterranean coast of Europe, it was domesticated from wild species. Lettuce has more dietary fiber and vitamin C than cabbage, which has the effect of eliminating excess fat, so it is also called weight loss lettuce; because its stems and leaves contain lettuce, it tastes slightly bitter, and has the effect of analgesia and hypnosis, lowering cholesterol, and assisting in the treatment of neurasthenia.
Lettuce comes in a variety of varieties, with different colors of green and purple, and if you mix different varieties, you will appreciate the magnificent colors of the garden. Lettuce is easy to grow and can be grown in pots almost all year round, making it an entry-level vegetable. Lettuce edible part of the water content of up to 94% ~ 96%, so raw food is crisp and refreshing, especially tender; the leaf meat is thicker, the texture is tender, the leaves are slightly bitter, the quality is good, and it is suitable for raw food or cooked food.
Varieties to be planted
Lettuce prefers a cool climate and is more hardy, so it is suitable for planting on south-facing, east-facing and west-facing balconies, and is generally planted in a soil manner in pots. However, lettuce leaves tend to become hard and bitter in the summer, so try to avoid summer planting. Lettuce is distinguished according to the color of the leaves, green lettuce and purple lettuce, and according to the growth state of the leaves, there are two kinds of loose leaves and knotted lettuce. The single plant of loose leaf lettuce weighs 250 ~ 500 grams, and the bulbous lettuce is longer than the growth period of loose leaf lettuce, the weight of each plant is large, generally 400 ~ 750 grams, and the late maturing varieties during the growth period can reach more than 1000 grams. Generally, family planting can choose loose leaf lettuce, common varieties of Rosa purple leaf lettuce, American large speed lettuce, Roman upright lettuce and so on. If you want to get a larger plant, you can transplant the seedlings in the nursery tray, and if you want to eat the young leaves, you need to sprinkle more seeds in the pot, and you can harvest while the seedlings are in between.
Planting season
Lettuce can be cultivated at all times except during the hottest season. Home balconies in North China can achieve annual production. Usually in April, May, September lettuce seedlings can be carried out in the open air, whether it is a balcony or a courtyard, from June to August to plant lettuce to take shade measures, from October to March of the following year need to be planted on the balcony.
Seedling methods and techniques
Lettuce seeds are small, and good conditions are required for germination and seedlings, so the planting method of seedling transplanting is more used. Seedlings can be bred when the average temperature is higher than 10 °C, and appropriate protective measures need to be used when it is below 10 °C. Summer seedlings should take measures such as shading and cooling. The pot soil strives to be fine and flat, and after the underwater seepage, sprinkle a thin layer of sieved fine soil in the pot, and then sprinkle the seeds.
Seed treatment: Wet the seeds with water in a Petri dish or gauze bag lined with filter paper, place them in a refrigerator freezer at 4 ~ 6 ° C for a day and night, and then sow seeds. In order to evenly sow seeds, the treated seeds can be mixed into a small amount of fine fluvo-aquic soil, mixed well and then sown, covering the soil by 0.5 cm.
Seedling stage management: the temperature at the seedling stage is controlled at 16 ~ 20 °C during the day and about 10 °C at night, and the seedling colonization is carried out when 2 ~ 3 true leaves are planted, and the film is covered on the pot. After slowing down the seedlings, proper water control is conducive to the root and seedling strength. The temperature varies greatly from season to season, generally from April to September, the seedling age is 25 to 30 days, and the seedling age is 30 to 40 days from October to March of the following year.
Planting
Grow lettuce can choose a small round pot with a capacity of 7 to 8 liters, and transplant 1 plant per pot, so that it can grow into a large lettuce, peel the outer leaves and harvest them layer by layer. You can also choose a larger rectangular pot, sprinkle more seeds, and harvest the seedlings while growing. The planting substrate is 2:1 grass charcoal nutrient soil and vermiculite, and then add 5% to 10% decomposition organic fertilizer is the best; 50% grass charcoal nutrient soil plus 25% garden soil plus 20% sandy soil plus 5% decomposition fine organic fertilizer can also be used.
Post-planting management
Watering: After slowing down the seedling water, it is necessary to grasp the number of watering depending on the soil moisture and growth. Generally, water once every 5 to 7 days. When the temperature is low in spring, the amount of water should be small, and the date of watering interval should be long; the water demand during the peak period should be more, and the soil should be kept moist; watering should ensure the plant's need for water, but also can not be excessive, and the humidity control should not be too large to prevent diseases.
Weeding in middle cultivation: After colonization of slow seedlings, the nutrient soil in the pine flower pot should be often loosened to enhance soil permeability and promote root development. During the growth period, the soil should be kept moist, pay attention to weeding and drought-resistant fertilizer, and pay attention to the prevention and control of aphids in high temperature and drought. In the late growth period, the water should not be too much, so as not to lead to the occurrence of soft rot and sclerotia, and the watering principle is to water frequently. To reduce its bitterness and make its texture more tender, it can be softened. That is, in the summer, when the leaves of the plant grow luxuriantly, the outer leaves are lifted, tied to the top and cultivated, and the yellow and white lettuce of the inner leaves can be harvested after 15 to 20 days.
Pest control
The main insect pests in lettuce are aphids and so on. When the amount of insects is small, manual capture can be used, and when there are more, biopesticides can be sprayed.
Harvest
When the lettuce is harvested, the entire plant can be cut off, or the outer leaves can be peeled and harvested layer by layer, so that the harvest time can be extended. Generally, about 100 days after sowing, the leaves have been fully grown, and the appearance of the plant has been fully harvested.