How to Grow Onion

Onion, one of the oldest vegetables used by mankind, is a culinary ingredient in almost every dish, raw or cooked. Revered by the ancient Egyptians for its spherical shape and concentric rings (as a symbol of eternal life), the onion is known for its wide range of medicinal properties. It is believed to have anti-inflammatory, antioxidant and anti-cancer properties, and even helps lower cholesterol levels. It is very rich in vitamin C, chromium and flavonoids, with a characteristic pungent smell, imparted by high sulfur content. Onion being one of the most sought-after vegetables is not very hard to cultivate, so you can also develop your own onion garden.

Soil Type
Onions can be grown in almost every soil type, viz. sand, loam or clay. But the important thing is that the soil should be firm and well-drained, i.e. moist, but not soggy. Good drainage is very important for preventing the flooding of the soil. Onions generally grow well in acidic soil having pH between 5.5 to 6.5. You should select a plot which gets sufficient sunlight, preferably for 6 hours a day. Adequate soil moisture is most important for growing onions.

Preparation
In preparing the land for onion cultivation, first it should be tilled properly. As composting helps improve soil, manure or organic compost can be added to it. Fertilizers can also be used, but the variety which are high in nitrogen are not suitable, as they are more likely to produce small bulbs with green, overgrown tops. Manure or organic compost should be added a few weeks before sowing the onion seeds. You can also moisten the soil with water, a day before sowing. To make the soil firm, tread on it gently.

Sowing
While growing onions, you can either opt for seeds or onion sets. An onion set is a small, partly grown dormant onion. Sets have certain advantages over seeds, like they can be grown quickly and also require less skill and labor. If you are planning to grow onions from seeds, then sow them about 2cm deep into the soil. Remember to keep a proper distance between seeds, usually a distance of about 1 inch would be sufficient. If you are going to sow in rows, the distance between rows should be about 30cm. This row distance is also applicable, if you are planting onion sets. However, the sets (unlike the seeds) should be planted 10 to 11cm apart.

Seeds would usually take two to three weeks to germinate. Once the seedlings reach a height of 5cm, they would require thinning. While thinning, place them around 3 to 4 inches apart, to avoid crowding. Providing the required amount of water is important in onion cultivation. Watering, once a week would be sufficient, till the tops begin to fall or become yellow, which indicates that the bulbs are about to reach maturity, and then watering can be stopped.

Onions can also be grown in soilless mixture. Soilless mixture does not contain soil, but various other ingredients like peat moss, composted pine bark, sand, perlite, vermiculite and small amounts of limestone, other minerals or fertilizers. To grow onions in such a mixture, seeds should be sown, approximately ¼ inch deep into the soil, and covered with the soilless mixture. They should germinate in about 2 weeks, after which they can be grown in peat pots or cell packs. When they reach a diameter of about ¼ inch, they can be planted in a vegetable garden.

Nowadays, many varieties of onions are available and they can be grown in different seasons, for example the maincrop onion seeds or sets can be sown from late February to early April, while salad or spring onions can be grown from March to July. Japanese variety of onion seeds or sets are generally planted in early September.

Harvesting
The maturity of the onion bulbs is indicated by the color and size of the tops. When the tops turn yellow or begin to fall, it indicates that the bulbs are approaching maturity. Usually, harvesting is done, when the top reaches a height of around 6 inches or a week after the tops turn yellow or start falling off. While harvesting, one should be careful not to damage the skin of the onions, as this would help certain organisms in attacking and decaying the flesh. So, lift the onions gently out of the ground and remove the soils from their surface. You can keep them above the ground for few days, which would help in drying out the tops. Once the tops dry out, remove them from the bulb. Generally, sunny days are ideal for harvesting onions.

Onion cultivated sites are often seen to be pervaded with undesirable weeds. These weeds can hamper the growth of onions, especially the young seedlings, as they grow very slowly. Many herbicides are available in the market, but excessive use of them can cause damage to the onion plants. Therefore, frequent removal and control of weeds is necessary to facilitate proper growth of onions.