Detailed Explanation of the Key Techniques for Soilless Cultivation of Lettuce

First, choose a suitable variety, then germinate the seeds, and sow them once the seeds show white sprouts. The seeds can be sown directly into planting cups, 1-2 seeds per cup, covered with a layer of substrate after sowing, watered thoroughly with clear water, and left to emerge. When the seedlings have 6-7 true leaves, they can be transplanted; after transplanting, simply manage the nutrient solution and temperature well.

1. Varieties

The lettuce varieties used in soilless cultivation include Soft-tail lettuce, Italian lettuce, Emperor, Great Lakes 366, Great Lakes 118, Crispy, Martha, mini-type lettuce, and others.

2. Germination

Soak the seeds in clear water at about 20 degrees for 3 to 4 hours, rub and wash them, drain off the water, then place them on a clean, moist gauze and germinate them at 15 to 20 degrees. Generally after 2-3 days, the seeds will show white sprouts, and at this point they can be sown.

3. Sowing

Sow the seeds directly into planting cups filled with a fixing medium such as vermiculite, or into seedling trays filled with a seedling substrate, sowing 1-2 seeds per cup, then cover them with a layer of substrate. Then cover with a shade net, water thoroughly with clear water, keep them moist, and wait for emergence.

4. Transplanting

When the seedlings have 6-7 true leaves, this is the suitable period for transplanting. About 10 days before transplanting, water should be appropriately controlled according to the condition of the seedlings. When planting the seedlings, first stand the seedling upright in the center of the nutrient pot, then fill vermiculite around the seedling.

5. Nutrient Solution

The nutrient solution formula uses a lettuce-specific formula or a general leafy vegetable formula. A nutrient solution formula suitable for lettuce growth is (grams/ton): calcium nitrate 621, potassium nitrate 444, monopotassium phosphate 330, magnesium sulfate 500, ammonium nitrate 69. Or use the Japanese garden trial formula: calcium nitrate 945, potassium nitrate 809, potassium dihydrogen phosphate 153, magnesium sulfate 493. During the growth period, the concentration, pH, depth, and nutrient supplementation of the nutrient solution will change.

6. Temperature

Lettuce prefers a cool climate, with a suitable growth temperature of 15-20°C. It grows best in an environment with a large day-night temperature difference and low nighttime temperatures. The daytime temperature can be maintained at 18-20°C; above 25°C, ventilation should be provided, and the nighttime temperature should be maintained at 10-12°C.