Onions are an edible bulb. They are members of the allium family along with chives, garlic, leeks, shallots and ornamental alliums. Onion bulbs are round or oblong and are composed of concentric layers. They can either have a pungent smell or be quite sweet, depending on the variety.
Some onions are sensitive to day length, while other can grow regardless of the day length (how much daylight there is when onions stop forming).
Short Day Onions (10 to 12 hours) - Red Burgundy
Long Day Onions (14 to 16 hours) - Walla Walla
Day Neutral - Candy
To grow bulb onions in a container, make sure to use a container that is at least 8 to 10 inches deep.
Although it is believed that onions originated in Asia, it is likely they have been growing wildly on every continent for 5000 years or more. It is likely that onions were one of the earliest cultivated crops because they were less perishable than other foods at the time.
Onions were not just a source of food, however. In Egypt, onions were worshipped - they symbolized eternity because of the circle within a circle anatomy. They were also used frequently as medicine. In Ancient Greece, the athletes in the Olympic Games would consume pounds of onions, drink onion juice and rub onions all over their bodies.
Onions that mature in cool weather tend to be sweeter, while those maturing in hot weather are stronger flavored.
If you want to store onions over the winter, you can cure them by hanging them in a well-aired place. Mesh bags or strings can be used to group and hang onions and they should hang for about 3 to 4 weeks.