Onion planting and cultivation technology

Onion is a very common seasoning vegetable with strong temperature adaptability. At temperatures between 3 and 5°C, seeds and bulbs can germinate slowly, while at 12°C the germination rate will accelerate. The suitable temperature range for onion seedling growth is 12-20℃, the suitable temperature for leaf growth is 18-20℃, and the suitable temperature for bulb growth is 20-26℃. In addition, the healthy seedlings can withstand low temperatures of -6 to -7 degrees Celsius. Let’s learn about the planting and cultivation techniques of onions.

1. Cultivated land and fertilization

Ten days before sowing, till the land and evenly apply fully decomposed, crushed and sifted farmyard manure, with the amount of fertilizer applied not exceeding 2,000 kg per mu. Then till the soil twice to a depth of about 20 cm or more to thoroughly mix the fertilizer with the soil. Then use a harrow to level the bed surface in preparation for sowing.

There are two types of ridge specifications: one is a small high ridge with a ridge width of 1.6 meters, a ridge ditch width of 0.2 meters, a ridge ditch depth of 0.1 meters, and 8 rows transplanted per ridge, which is suitable for clay soil or relatively flat fields. The other type is flat bed, with a width of 2 meters, a ridge width of 0.27 meters and a height of 0.2 meters. There are 10 rows planted in each bed, and it is suitable for sandy soil.

2. Transplanting and density

The transplanting period is divided into: the suitable transplanting period for fields covered with film is November 15th to 20th (around the beginning of winter); the suitable transplanting period for fields not covered with film is October 20th (around the beginning of frost). The density should be adjusted accordingly according to soil fertility, fertilizer level and management level. The general planting row spacing is 20 cm, the plant spacing is 16~17 cm, and the density per mu is about 20,000 plants. To prevent bolting, select seedlings of moderate size with a leaf sheath diameter of 6 to 7 mm and a single plant fresh weight of 4 to 6 grams. Eliminate large, weak and inferior seedlings. Before transplanting, large and small seedlings should be planted separately and managed in grades to achieve balanced increase in yield.

4. Field management

Watering: Onions enter the seedling growth period about 20 days after planting. Since the temperature is relatively low during planting, it is not advisable to water in large quantities. Excessive watering will lower the ground temperature and slow down the growth of seedlings. At the same time, the new roots of the newly planted seedlings have not yet sprouted and cannot be short of water. Therefore, at this stage, onions should be watered in small amounts and multiple times.

After wintering, the plants turn green again and enter the stem and leaf growth period. During this stage, you need to water the plants to promote growth, but also control watering to prevent excessive growth. The method of controlling watering is called "squatting seedlings". Squatting seedlings should be controlled according to the weather, soil properties and growth conditions after planting. Under normal conditions, the squatting period is about 15 days. When the outer leaves of the onion seedlings turn dark green, the wax content increases, the leaf flesh becomes thicker, and the heart leaves become darker in color, stop squatting and start watering. After that, water every 8 to 9 days to keep the soil moist to promote plant growth and prevent excessive growth. Stop watering 7 to 8 days before harvest.

Fertilization: Onion fertilizer requirements are 13-15 kg of nitrogen, 8-10 kg of phosphorus, and 10-12 kg of potassium per acre. Pay attention to the application of phosphorus and potassium fertilizers, and avoid excessive nitrogen fertilizer, so as not to cause excessive growth of the aboveground part, bolting or delayed bulb enlargement.

Before and after the spring-sown onion seedlings emerge from the soil, keep the soil moist, water frequently, and cultivate frequently. The peak leaf growth period and bulb expansion period are the times when onions require the most fertilizer and water, so fertilizer and watering should be applied in a timely manner. Apply 10-15 kg of diammonium phosphate, 15-20 kg of diammonium phosphate, and 3-5 kg ​​of potassium sulfate per 667 square meters.

Loosening the soil: Loosening the soil is beneficial to the development of onion roots and the expansion of bulbs. Generally, the soil should be loosened 3 to 4 times during the seedling stage, combined with each watering; the soil should be loosened 2 to 3 times during the stem and leaf growth period, and intertillage should be stopped after the plants are covered with ridges. The depth of intertillage should be about 3 cm, it should be shallow near the plants and deep away from the plants.

Stalk removal: For onions that shoot early, cut off the lower part of the flower bud before the flower ball is formed, or separate it from the tip of the stalk and tear it into two pieces from top to bottom to prevent flowering from consuming nutrients, promote the growth of side buds, and form a fuller bulb. Practice has shown that for plants that sprout early, a certain yield can still be obtained after taking measures to remove the sprouts.

The above is an introduction to the key points of onion cultivation technology. When planting onions, you should pay more attention to the details mentioned above. Of course, you also need to adjust the planting plan based on the actual situation.