When is the best time to plant onions?

Onion , a biennial herb of the genus Allium in the Liliaceae family, originated in Central Asia or West Asia. In China, onions are widely grown in various regions. Due to their strong adaptability and easy storage and transportation, onions have become one of the important vegetables to balance market supply and fill the off-season. Let’s learn together when is the best time to plant onions?

When is the best time to plant onions?

Onions prefer warm and dry climatic conditions but are sensitive to high temperatures. Therefore, autumn is the ideal season for sowing onions. As the temperature gradually drops in September, the weather becomes cooler, which provides a suitable environment for the growth of onions. Dry autumn weather with little rainfall also helps the onion bulbs develop into a spherical shape. It is generally recommended to sow in mid-to-early September to ensure that the onions can survive the winter smoothly and avoid affecting their quality due to sowing too late. The best sowing time in the Huanghuai River Basin is early to mid-September. In the southern region, it is recommended to sow in late September to early October and transplant in mid-to-late November. Sowing too early may cause the seedlings to be too large, which will easily lead to sprouting after winter; while sowing too late may cause the seedlings to be weak, lack cold resistance, and have poor bulb development, affecting yield.

Onion cultivation technology

1. Seedling preparation

When sowing onions, you should choose well-drained and fertile soil as the seedbed, and the sowing amount per mu is about 0.2 kg. After sowing, cover with a thin layer of soil or wood ash, spread rice straw or wheat straw on it, and then water to keep the soil moist. After about 8 to 10 days, the seedlings will break through the soil and the covering can be removed. During the seedling stage, attention should be paid to properly control water and fertilizer to avoid the seedlings being too large and causing premature bolting, and thinning should be carried out in a timely manner to remove seedlings that are too dense or growing poorly.

2. Planting

Onion planting should be completed before winter arrives. In the southern regions, planting is usually carried out from November to early December. When planting, the seedlings should be graded according to their size to ensure that seedlings of the same grade are planted together. For larger plants, you can control the fertilizer and water appropriately; for smaller plants, you need to apply appropriate fertilizer and water. The number of plants planted per mu is about 17,000 to 20,000, the row spacing is maintained at 20 to 26 cm, the plant spacing is 13 to 17 cm, and the planting depth is about 3 cm.

3. Field management

During the wintering of onion seedlings, the demand for fertilizer is relatively low due to the small growth volume. When the temperature rises in spring, the plants begin to grow rapidly and a heavier fertilizer application is needed. From late March to early May, onions enter a period of vigorous growth and should be fertilized 1 to 2 times, with 200 kg of human and animal manure or 5 to 10 kg of urea and 5 to 8 kg of potassium sulfate applied per mu. When the bulbs are close to maturity, the supply of water and fertilizer should be stopped. In drought conditions, water promptly. Since onions have shallow roots, weeding should not be done too deeply to avoid damaging the roots.

4. Harvest

Onion harvest is usually scheduled from late May to early June. The early or late harvest time directly affects the yield and storage performance of onions. When the onion leaves gradually turn yellow from bottom to top, the pseudostem becomes soft and begins to fall over, the bulb stops expanding and the skin becomes tough, it indicates that the bulb is mature and should be harvested in time.

The above is an introduction to the sowing time of onions. Onions are generally best planted in autumn, but of course it also needs to be considered in combination with local environmental and climatic conditions.