Onions are commonly grown from seeds. Farmers should purchase seeds from reputable stores to ensure good plant development and high yields.
After purchase, onion seeds can be sown directly into the soil. However, to promote uniform germination and shorten the sprouting time, it’s recommended to pre-treat the seeds by soaking them in warm water (2 parts boiling, 3 parts cold) for 8–12 hours. After soaking, incubate the seeds until they begin to sprout before sowing.
Broadcast the onion seeds evenly on prepared soil or planting containers (avoid overcrowding, which wastes seeds). For optimal growth, use store-bought soil or mix your own using chicken manure, worm castings, rice husk, coconut coir, and organic compost. You can also add lime and let the soil sit for 7–10 days to eliminate harmful pathogens. The ideal soil pH for onion growth is 6.0 to 6.8. Plants can still grow in pH levels from 7.5 to 7.8, but root systems may die if the pH drops below 6.
Keep the soil consistently moist to support germination by watering once or twice a day. During growth, thin out weak, stunted, or pest-damaged plants. When seedlings reach 3–5 cm tall, remove any underperforming or diseased plants and those already forming bulbs.
After 40–50 days of seedling growth, when the plant has developed 4–5 leaves, it's ready for transplanting. The soil should be loose and well-prepared with decomposed manure mixed into furrows and topped with a thin soil layer. Space the plants 15 cm apart, with rows 20–25 cm apart. Water twice a day (morning and late afternoon) after transplanting.
Ten days after transplanting, apply a base dressing using organic fertilizers like cow manure, goat manure, or worm castings. Continue fertilizing every 15–20 days. Combine each fertilizing session with weeding and light soil cultivation. Note: Onions are not drought-tolerant, so regular watering is essential to maintain soil moisture.
Sau khi gieo ươm khoảng 40 – 50 ngày, cây ra 4 – 5 lá mới nhổ trồng. Đất trồng cần được làm tơi xốp, cho phân chuồng ủ hoại vào rạch và trộn đều với đất, phủ lên trên lớp đất mỏng. Trồng mỗi cây trồng cách nhau 15cm, hàng cách hàng 20 – 25cm. Sau khi cần xong cần tưới nước ngày 2 lần vào sáng sớm và chiều mát cho hành tây.
Sau khi trồng hành tây được 10 ngày thì tiến hành bón lót bằng phân hưu cơ, phân bò, phân dê, phân trùn quế… Sau đó cứ khoảng 15 – 20 ngày bón đợt tiếp theo cho cây. Mỗi lần bón phân kết hợp với việc vun xới và làm cỏ. Hành tây là loại cây chịu hạn kém nên thường xuyên phải tưới nước giữ ẩm cho cây.
