When to Plant and Harvest Onions? Plus High-Yield Cultivation and Management Techniques

Onion is one of the common vegetables, also known as bulb onion, round onion, Japanese bunching onion, onion head, Dutch onion, and is cultivated throughout China, especially in Fujian, Shandong, Gansu, Inner Mongolia, Xinjiang and other places. Onions are regarded by the elderly as a health vegetable; regular consumption can lower blood pressure, improve eyesight, prevent osteoporosis, and so on. In recent years, the popularity of onion cultivation has not diminished, so when are onions generally planted and harvested? How can high yields be achieved? What are the specific cultivation and management techniques?

I. When are onions generally planted and harvested?

Planting times vary by variety and region. Most varieties are sown in the open field for seedling raising in early September, and the suitable transplanting period is from mid-to-late October to early November.

Harvest usually takes place from late May to early June. When the onion leaves gradually turn yellow from bottom to top, the false stem softens and begins to topple; the bulb stops expanding, the outer skin becomes leathery, and it enters the dormancy stage, this marks that the bulb has matured and should be harvested promptly.

II. How to achieve high yields? Cultivation and management techniques included

1. Raise strong seedlings at the right time

The suitable sowing period for onions is around September 20. Sowing too early leads to a high bolting rate, while sowing too late makes the plants susceptible to frost damage. For direct seeding, prepare 300 grams of seed per mu; for seedling raising, prepare 50 grams of seed per 10 square meters.

First draw shallow furrows on the prepared seedbed surface, then evenly broadcast the seeds into the furrows. After sowing, cover with 1 cm of soil, firm it by treading, and water. On the fourth day after sowing, water a second time; on the eighth day, when sprouts appear on the bed surface, water a third time, ensuring three waterings for full emergence.

After full emergence, water lightly once every 7 to 10 days and weed once. Thin the seedlings appropriately, with a spacing of 3 to 4 cm. When mole crickets cause damage, add an appropriate amount of phorate to the water for control, and also pay attention to controlling gray mold. After the seedlings have grown for 30 days, apply a small amount of urea as a top dressing and spray potassium dihydrogen phosphate.

2. Choose a good transplanting time for onions

The suitable transplanting period for onions is early November. At transplanting, grade the seedlings first, planting the standard large seedlings first and the small seedlings afterward. The planting depth should be appropriate; too deep and the bulb easily forms a spindle shape with low yield; too shallow and the plants easily lodge. Burying the bulb about 1 cm is appropriate.

Onions should not be planted continuously on the same land. Apply 4000 kg of fully decomposed organic fertilizer, 50 kg of diammonium phosphate, and 30 kg of potassium sulfate per mu to the transplanting site. After fertilizing, level and harrow the land finely and make flat beds, with bed width depending on the width of the plastic film. Transplant at a row spacing of 20 cm × 15 cm, generally about 23,000 plants per mu. Water before covering with plastic film, then punch holes in the film, with holes 3 cm deep and 1.5 cm in diameter. At transplanting, insert the onion seedlings directly into the holes, press firmly by hand, and seal the hole openings tightly. If not covering with plastic film or if the field was not watered before covering, water promptly after transplanting and water again 4 to 5 days later to help the seedlings recover.

3. Scientific management

Water thoroughly once before the soil freezes; in late February of the following year, when the onion seedlings turn green again, water for greening; during the bulb expansion period, increase watering frequency, generally once every 6 to 8 days, keeping the ground alternating between dry and moist to facilitate bulb expansion; stop watering 10 days before harvest to aid storage.

III. Which onion varieties are good to grow in recent years?

There are many onion varieties, and by skin color they can be divided into three types: red-skinned, white-skinned, and yellow-skinned.

1. Red-skinned onions

Shanghai Red Skin, Jiangxi Red Skin and others are all good choices. They usually come to market in late May. This type sprouts early and tolerates transport and storage, so it is planted in many regions.

2. White-skinned onions

Xinjiang White Skin, Hami White Skin and others. However, they are not disease-tolerant and have low yields; they can be dehydrated and processed into other ingredients.

3. Yellow-skinned onions

Quanzhou Yellow No. 2, Jinqiu, Hongye Sanbao, Jinqiu No. 2 and others. Among them, the early-maturing variety Quanzhou Yellow No. 2 and the late-maturing variety Hongye Sanbao have good quality and tolerate transport and storage, but have low yields.

IV. What are the prospects for onion cultivation in 2019?

Do not plant blindly next year; take into comprehensive consideration the old onion stock in cold storage in Gansu and Shandong. The government and relevant agricultural departments should actively coordinate planting, shorten the overlap period between new and old onions as much as possible, and achieve reasonable and effective staggered marketing.