Onions are grown from sets, plants, or seed. Sets are small onion bulbs that are planted in the spring to produce green onions – scallions – or bulbs later in the season. Onions can be grown from seed, but seed produces onions latest in the season, and the small weak onion plant is difficult to weed or cultivate early in the season.
When to Plant: They grow well in cool or warm weather. They should be planted early so that as much growth as possible occurs before hot dry weather. Plant sets in mid March or plant or sow seed in early April.
Space: Onions may be grown in rows as close as 15”, with individual plants spaced 2-4” in the row, depending on the size of the bulb. Plant sets 1-1.5” deep, and plant transplants about the same depth.
Care: They have a shallow, inefficient root system and need regular watering and fertilizing for best results. Weed control is essential since they compete poorly with weeds and other crops. Watering may be reduced near the harvest period, but regular timely watering is needed until the tops begin to fall over. Large vigorous plants are essential for large bulbs with high yields.
Harvest: Onions are ready for harvest when the tops begin to weaken and naturally fall over. This is a signal that the bulbs are as big as they will get. Pull or dig the onions and store in a warm, dry, shaded location for 2-4 weeks until the tops and necks are completely dry. After the tops are dry, cut them, trim the roots, and store in a cool dry location. An open mesh bag is best for storage. Mild flavored onions keep for only a month or so. Stronger flavored onions keep 3-4 months.
Shallots are smaller than onions and are grown by planting a division or clove.
Garlic is a strong Flavored onion relative that is also grown by planting a division or clove in late summer.
Chives are grown for the green foliage. They usually grow in clumps.
Leeks require a long cool season for best results. They are usually planted in early spring and dug in late September to mid-October.