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  MG Manual Reference
Ch. 10, pp. 108 - 110

[Selected Crops: intro | asparagus | beans | broccoli | brussels sprouts | cabbage | cauliflower | sweet corn | cucumbers | eggplant | lettuce | melons | onions | peppers | potatoes | squash | tomatoes | herbs | herb use ]


Light: Sunny. (Green onions tolerate partial shade).
Soil: Well-drained loam.
Fertility: Medium-rich.
pH: 5.5 to 7.0
Temp: Cool (45 to 60° F) during development. Medium-hot (60 to 75° F) during bulbing and curing.
Moisture: Moist, but not waterlogged.
Planting: Use sets, seeds, or transplants in the spring for bulbs and for green or bunching onions. Seeds may be started indoors 8 weeks before setting out; use sets in the fall for perennial or multiplier types of onions.
Spacing: 1 to 6 inches by 12 to 24 inches for standard spacing; 4 inches by 4 inches for wide row in rows up to 2 feet apart. Plant close, then thin using thinnings as green onions.
Hardiness: Hardy biennial -- bulb onions, green or bunching ongoing; Hardy perennials -- Egyptian onions or perennial tree and multiplier.
Fertilizer Needs: Heavy feeder. Apply 4 to 5 pounds 10-10-10 per 100 square feet before planting. Use starter solution for transplants. Sidedress 1 to 2 weeks after bulb enlargement begins using 3 tablespoons 33-0-0 per 10' row.

Onions are often grouped according to taste. The two main types of onions are strong flavored (American) and mild (often called European). Each has three distinct colors, yellow, white, and red. In general, the American onion produces bulbs of smaller size, denser texture, stronger flavor, and better keeping quality than European types. Globe varieties tend to keep longer in storage.
Onion varieties also have different requirements as to the number of hours of daylight required to make a bulb. If the seed catalog lists the onion as long day, it sets bulbs when it receives 15-16 hours of daylight and is used to produce onions in Northern summers. Short day varieties set bulbs with about 12 hours of daylight and are used in the deep South for winter production.
For green or bunching onions, use sets, seeds, or transplants in spring, or use Egyptian (Perennial Tree) and the Yellow Multiplier (Potato Onion) sets in the fall.
For bulb production, plant sets in early spring. Set one to two inches apart and one to two inches deep in the row. Thin to four inches apart and eat the thinned plants as green onions. Avoid sets more than an inch in diameter because they are likely to produce seed stalks. Too early planting and exposure to cold temperatures also causes seed stalk development. Some people have best bulb production using seedlings or transplants rather than sets. Egyptian Tree or Multiplier onions should be set in late October or early November. Plant four inches apart in rows one to feet apart. Distance between rows is determined by available space and cultivating equipment. Plant seed in October or November in warm areas of Arizona.
Bulbs compete poorly with weeds due to shallow root systems. Shallow cultivation is necessary, do not hill up soil on onions as this can encourage stem rot. Insure ample moisture especially after bulbs begin enlarging.
Onions should be harvested when about two-thirds of the tops have fallen over. Careful handling to avoid bruising helps control storage rots. Onions may be pulled and left in the field for several days to dry then cured in a well ventilated attic or porch for one to two weeks out of direct sun. Tops may be left on or cut off; but leave at least one inch of the top when storing. Thorough curing will increase storage life.
Diseases: Neck or stem rot, bulb rot.
Insects: Thrips, onion root maggots.
Cultural: Bulb rot from bruising, insufficient drying; split or double bulb from dry soil during bulb formation; very small bulb from too late planting or too dry soil.
Days to Maturity: 100 to 120 days for mature bulbs.
Harvest: Harvest green onions when tops are 6 inches tall. Harvest bulbs after 2/3 or more of the tops have fallen over. Do not wait more than 1 to 2 weeks after this occurs. Allow for thorough drying before storage.
Approximate yields: 10 to 15 pounds per 10-foot row.
Amount to Raise: 10 to 15 pounds per person.
Storage: Cool (32° F), dry (65 to 70% relative humidity) conditions for 6 to 7 months.
Preservation: Onions may be stored dry or pickled and canned. They freeze well if chopped and covered with water. For fresh storage, maintain good air circulation. One effective storage method is to place onion in discarded hosiery, tie a knot, and add another onion. When hose is filled, suspend from rafters in storage area.

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