A Detailed Guide to Efficient Lettuce Cultivation Methods and Biological Characteristics

Lettuce is one of the common vegetables in our daily lives. It not only has practical value but also medicinal value, and can be used for clearing heat and reducing blood lipids, among other purposes. Because it contains a variety of vitamins, its health benefits are also quite good. Below, let us take a look at the introduction to lettuce's biological characteristics and efficient cultivation methods.

I. Biological characteristics of lettuce (cultivation conditions)

1. Climatic conditions

Lettuce prefers a cool climate. The minimum temperature for seed germination is 4°C, and germination takes a long time. The optimum temperature for germination is 15-20°C, with germination in 3-4 days; above 30°C, germination is impeded. Therefore, when sowing in summer, low-temperature treatment is necessary to promote enzyme activity within the seeds and the transformation of other substances. The optimum temperature for stem and leaf growth of head lettuce is 11-18°C, and the optimum temperature during the head-forming stage is 17-18°C. Seedlings can tolerate -5°C. At low temperatures above 21°C, heads are not easily formed, or because the temperature inside the head is too high, the heart leaves become necrotic and rot. When the temperature is above 30°C, growth is poor. The temperature adaptation range of non-heading lettuce is broader than that of head lettuce. In terms of sensitivity to photoperiod response, early-maturing varieties are the most sensitive, mid- and late-maturing varieties are next, and late-maturing varieties respond sluggishly.

2. Moisture conditions

Lettuce has different water requirements at different growth stages. During the seedling stage, it must not be dry or too wet; if too dry, the seedlings tend to age, and if too wet, the seedlings tend to grow leggy. During the rosette stage, water should be appropriately controlled. During the head-forming stage, water must be sufficient; a lack of water results in small leaves and a bitter taste. In the late head-forming stage, water should not be excessive, so as to avoid head splitting, which leads to disease.

3. Soil conditions

Lettuce is suited to slightly acidic soil. When planted in soil rich in organic matter, it has strong water- and fertilizer-retention capacity and high yield. If planted in dry, water-deficient soil, the root system develops incompletely, growth is not plump, the vegetable tastes slightly bitter, and quality is poor.

II. Introduction to efficient lettuce cultivation methods

1. Variety selection and seasonal arrangement

Lettuce prefers cool conditions. It grows best in winter and spring within the 15°C-25°C temperature range. Below 15°C it grows slowly, and above 30°C it grows poorly and is very prone to bolting and flowering. For hydroponic lettuce, loose-leaf lettuce varieties are suitable.

2. Nutrient solution preparation and selection of cultivation containers

For the nutrient solution formula, choose to add 600 grams of calcium nitrate, 600 grams of potassium nitrate, 350 grams of magnesium sulfate, and 150 grams of ammonium dihydrogen phosphate per ton of water; for micronutrient fertilizer, choose a general-purpose formula. In production cultivation, cultivation troughs or cultivation pools can be used; for home cultivation, pots, basins, boxes, and the like can be used, as long as they do not leak water.

3. Raising seedlings and transplanting

(1) Raising seedlings: Take a seedling tray and use vermiculite as the seedling substrate. Before sowing, soak the vermiculite thoroughly with water, evenly scatter the seeds on top of the vermiculite, then cover with a layer of vermiculite equivalent to one times the amount of seed, and water thoroughly. At a temperature of 20°C, seedlings can emerge in 5-7 days. After emergence, water with a nutrient solution having an EC value (electrical conductivity, the main indicator of water quality standards) of 1.6-1.8.

(2) Transplanting: Take a foam board and punch a hole every 20 cm with a hole diameter of 2.5 cm, and cover the mouth of the hydroponic container tightly. Place nutrient solution in the container with an EC value of 1.6-1.8. When the lettuce seedlings grow to 2 true leaves, carry out seedling separation and transplanting. First, wash the vermiculite off the seedling roots, wrap a strip of sponge around the stem base, and then insert the seedling into the hole in the foam board. Keeping the stem base area dry and breathable can greatly reduce the occurrence of diseases at the root-stem base.

4. Management and harvesting

The management process for hydroponic lettuce is very simple. After transplanting, to keep the nutrient solution level stable and consistent, add nutrient solution once every 2-3 days, with a water temperature of 20°C-22°C and a pH value of 6-6.5. When the seedlings have 3-4 true leaves, adjust the EC value to 1.8-2, continue adding nutrient solution as needed, and in about 20-25 days they can grow into marketable vegetables.

For home cultivation, the method of picking leaves can be used, harvesting and eating at any time to keep them fresh. In production, harvesting is generally done all at once. To intuitively show the characteristics of hydroponic vegetables, it is better to keep part of the pure white root system. In order to reduce the nitrate content in lettuce, one week before harvest, there is no need to supplement nutrients; only add clean water.