First, nursery:
1. Sowing time: Depending on the specific requirements of the product, sowing can be done throughout the year. The best yield is achieved through autumn sowing when the average temperature is between 16.5°C and 17°C. This is typically around late October. Climate conditions vary across different regions in the country, so the planting time should be adjusted accordingly. The goal is to ensure that seedlings are strong enough before winter. It's important to pass the spring safely, and the standard for pre-winter seedlings is to have two leaves and one heart. Spring sowing usually takes place around the Qingming Festival.
2. Seedbed preparation: The seedbed should be located on flat, fertile land with easy access to water and good drainage. Before plowing, the field should be lightly tilled. Apply 50 kg of compound fertilizer, 2.5 kg of Mushi Nan Dan, and 0.5 kg of carbendazim powder to kill soil pests and pathogens (very important). Create long beds of 20-25 meters, 1 meter wide, with 30 cm furrows and ridges. Compact the ridges and level them using a rake repeatedly to ensure evenness without any uneven areas.
3. Sowing: Before planting, remove the top soil from the bed, then fill it with water (a large amount is needed). After the water has been absorbed, mix the seeds with sand and evenly sprinkle them twice into the bed. Finally, cover the soil with a thickness of 1.5-2 cm. The soil coverage should be even. Use about 1.3 kg of seeds per 3-5 mu of green onions. The next morning, use a shovel to gently loosen the surface to prevent uneven covering.
Second, seedling management:
After 7 days of autumn sowing, the seedlings are ready for transplanting in spring after 8-12 days. Control watering before the cotyledons straighten to avoid soil compaction. During rainy periods, lightly cultivate the soil. When the first watering is given, wait until the cotyledons are straight. Weeding is essential, but herbicides should not be used. Once the seedlings reach about 2 cm, apply fungicides regularly every 5 days (mainly for root rot, virus, and gray mold diseases). Once the seedlings grow over 5 cm, apply urea according to the soil condition to promote growth.
Before winter, focus on cultivating strong seedlings. The standard is a plant height of 8-10 cm, with two leaves and one heart, green and strong leaves, and a base diameter not exceeding 0.3 cm. During this period, water 1-3 times based on soil moisture, and pour frozen water before freezing. Mix the soil with woody ash or fine-circle fertilizer, and ensure the leaf sheath thickness is not obvious.
After the autumn seedlings emerge in spring, the roots, hearts, and leaves of the onion sprouts begin to grow. Remove the sputum to clear out debris to prevent the seedlings from getting too moist, warm, and start growing early. In the first ten days of March, avoid premature action to prevent low temperatures from affecting early growth. Combine watering with applying 10 kg of urea per acre. From late March to early April, when the plants reach about 30 cm, thin them 1-2 times, keeping the density at 3-5 cm. By late April to early May, when the plants reach about 50 cm, they enter a rapid growth phase. Proper fertilizer and water management is crucial, with at least two to three applications of urea, ammonium nitrate, etc., each 10-15 kg, combined with spraying and micro-fertilizer application 2-3 times. Timely use of drugs to prevent fungal diseases, paying special attention to controlling onion flies and leaf miners. Stop watering 15 days before transplanting to ensure stable growth.
Third, transplanting and planting:
1. Choose a terrain with good drainage and fertile soil. The best direction is north-south. Apply manure as base fertilizer, 5000 kg, 100 kg of fertilizer, 10 kg of urea, 15 kg of potash, or 30 kg of diammonium phosphate, or 50 kg of compound fertilizer. Plow the soil dry to eliminate disease sources, weeds, and improve fertility. Then create furrows 80 cm apart, with a depth and width of about 25 cm.
2. The suitable planting period is usually mid-June to early July. Water the roots deeply before lifting, shake off the soil, and lay the seedlings flat for two days to remove weak seedlings and diseases. Sort by size, height, and thickness into three categories. Transplant the healthy seedlings while keeping them fresh. The spacing should be 3-4 cm.
3. Planting methods:
Dry planting method: After digging the furrows, arrange the onion seedlings along the sides of the furrow wall at a certain distance, flatten the leaves against the wall, and cover with soil. Ensure the soil is deep enough without covering the heart. Alternatively, use a shovel to plant at intervals and step on the soil. After planting, water it immediately. Avoid removing it if possible.
Hydroponics: Place the selected seedlings on the back ridge, evenly spaced, and first water the ditch. After the water seeps in, place one person every 8-10 meters. When cutting, use peeled branches to make a plug, with a "V" shape on top. Hold the seedlings with your left hand and the stick with your right, insert the plug into the wet soil at the bottom of the ditch, ensuring the onion is straight. Different grades of seedlings should be planted in separate plots to avoid mixing and uneven growth for easier management.
Fourth, post-plant management:
After transplanting, the hot season begins, with high temperatures and rain. Generally, no watering is needed; excessive rain may cause root rot and seedling death, so timely drainage is essential. In case of high temperatures and drought, watering is necessary to cool and promote growth. As the light blue long stretch continues, earth, fertilizer, and soil cultivation should be carried out simultaneously. The first time should start from Liqiu, applying 5,000 kg of fertilizer and 10-15 kg of urea. The second topdressing is during summer, with 15-20 kg of urea and 50 kg of cake fertilizer. The third topdressing is during Bailu, when the scallions enter the expansion period. At this stage, proper fertilizer and water management is critical. Apply 1000 kg of manure and urine, 15 kg of urea, 50 kg of phosphate fertilizer, 5-10 kg of potassium fertilizer, and finally water. The fourth topdressing is during the autumnal period, applying 10-15 kg of urea to the soil and watering. Spray compound micro-fertilizer before and after Bailu, generally once every 5-7 days, even up to 2-3 times, which significantly improves yield.
Fifth, harvesting and storage:
Before and after the beginning of winter, onions need to be harvested in considerable quantities. Bundle them at about 15 kg per bundle, place them in a well-ventilated area, tie 5-6 lines, and keep the space between the lines at 50 cm. If there is high temperature, dry them and avoid bundling. They are afraid of heat during storage, but not cold, and should be protected from rain.
Sixth, main pests and diseases:
1. Leaf miner: Mainly harms the leaves, with larvae entering the mesophyll, leaving white lines due to chlorosis.
2. Onion fly: Mainly harms the leaves, sucking them to form white spots, and in severe cases, the entire leaves turn grayish white due to chlorosis.
3. Rot: Mainly affects the underground parts of the onion, causing stem rot and withered leaves, leading to lack of seedlings.
4. Green onion purple spot disease: Affects the green leaves, starting from small white spots expanding to 3-5 cm, fusiform or jujube-like, with the largest lesion reaching 6-7 cm, slightly concave and dark purple, hence the name.
5. Green onion downy mildew: Diseased plants become twisted and dwarfed, with yellow-white oval lesions like water immersion, and drooping, dry leaves.
6. Scallion rust: Commonly known as red peony, it is a devastating disease in green onion production areas. Lesions appear on the surface of tubular leaves and stems, initially round, elliptical, or spindle-shaped, standing upright along the veins, turning from dark yellow to orange-brown, bulging, scattered, and varying in size. Infected plants turn yellow, dry, and fall, reducing production.
The above planting experience is for reference only, and each region should manage it in conjunction with local planting experience and climatic conditions.
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