Contributed by The Old Farmer’s Almanac Staff. Extracted from TSC’s web site on 3/25/17.
As the days grow longer, the time draws near to get the alliums going!
What is an allium?
Alliums are more familiarly known as onions and include garlic, leeks, and chives as well as numerous ornamental plants. In fact, the allium family has more than 1,000 plant varieties!
The most widely cultivated allium species is the common onion (Allium cepa; cepa in Latin means “onion”). These are the onions that we use to flavor cooked foods, that enhance fresh salads, and, tradition suggests, that keep colds at bay and relieve ailments. Gardeners have three onion options: yellow (aka brown) onions, white onions, and red (aka purple) onions—but there is no need to choose: Most gardeners can grow all three in one season.
Long- and Short-Day Onions
Onions are photoperiodic. This means that they are sensitive to daylight, or the length of day; the number of daylight hours affects their growth. Thus, they are referred to as long-day onions and short-day onions. Deciding which to grow depends on where you live: Imagine a line from the border between North and South Carolina to San Francisco (approximately 36° northern latitude). For best results, folks north of the line should plant long-day onions (‘Walla Walla’, a sweet onion; ‘Red Florence’; or ‘Yellow Globe’); folks south of the line should plant short-day onions (‘Crystal Wax White Bermuda’, ‘Red Burgundy’, or ‘Hybrid Yellow Granex’).
Confused by the long and short of it? Go neutral: Day-neutral (aka intermediate) onions will produce an excellent crop in any part of the country. Varieties include ‘Super Star’ (a mild white onion), ‘Candy’ (yellow), and ‘Red Stockton’ (red).
The varieties noted here are only a few of the possibilities. Consult your local supply store for alternatives and guidance in choosing.
Seeds or Sets?
Onions can be started from seed or bought as “sets” (tiny bulbs, ideally no more than 3/4 of an inch in diameter), bagged or loose by the pound. Seed onions keep better than sets, and seeds offer a greater choice. However, onion seeds need to be started indoors; they need temperatures above 50°F to germinate. Sets go right into the ground.
Aside from light, onions are pretty easy to please: They grow best in well-composted, slightly sweet (near-neutral pH) soil. Onions are sensitive to the crops that occupied the soil before them: They grow best if planted where lettuce or squash grew last season; they fare poorly if they follow a cole crop such as cabbage or broccoli.
Onions appreciate an early start, and cool temperatures encourage leaf growth. A light frost will do them no harm, and a late season snow is sometimes called an “onion snow”—also not a worry. Keep the soil moist and cool; mulch helps to do this while also discouraging weeds that steal precious nutrients from the soil of your shallow-growing bulbs.
Harvest by the Handful
Onions are ready to be lifted (pulled) from the ground when their foliage begins to dry out and fall over. When that happens, push the foliage to the ground and withhold water for about a week. Remove them from the soil and lay them in the sunlight to dry or in an airy, dry place protected from rain. This also toughens the skin, which improves storage.
Once cured, store them in a cool (40° to 60°F), dry, ventilated area inside a hanging mesh bag or box (no more than two deep) or as a braid. Do not store onions in a refrigerator; it is too damp. Sweet onions need slightly different care: They do not like to touch each other in storage, so slip them into an old nylon stocking, tying a knot between each onion. Then hang them in a cool, dry place.
• In the Middle Ages, it was believed that onion juice could cure baldness, snakebite, and rabies.
• Early American settlers believed that a meal of bread, milk, and onions helped to maintain good health.
• A raw onion rubbed on a bee sting or insect bite will relieve the pain and itching.