Green onions have been cultivated for centuries in various forms and are produced around the world. China is a significant producer and the United States ranks in the global top ten. Domestically, California leads production, with a handful of other states including Arizona, Georgia, Texas, and the Pacific Northwest contributing to annual supply. Imports from Mexico continue to rise to meet demand, especially during the U.S. off season.
Green onions are often referred to as bunched or spring onions, salad onions, or scallions. Each refers to a densely planted, mild flavored, immature bulb onion of the common Allium cepa species.
Many of today’s cultivars are hybrids of Allium cepa and Allium fistulosum (a Japanese bunching onion), which can produce either bulb or nonbulb plants. Day-length (short-day or long-day varieties dependent on hours of sunlight) influence growth characteristics, such as bulb development and size.
Varieties vary greatly, but White Lisbon is widely grown; Crystal Wax, Ebenezer, Eclipse, Hishiko, Ishikura, Kincho, Sweet Spanish, Tokyo Long, White Globe, and White Portugal are among the many other varieties available for growers depending on region and market specifications.
Green onions should be planted in mild climates with well-drained loamy soil and require regular irrigation during development. Due to shallow roots, plants are unable to compete with weeds, which will put young plants at risk. Plants are also vulnerable to wind and hail damage, as well as cold temperatures.
Once onions reach from a quarter- to half an inch in diameter and tops reach 6 to 8 inches in height, harvest begins by hand. Green onions are gathered and banded into bunches. Due to high perishability, bunches should be cooled immediately. Tops are generally trimmed to market specifications.
Pests & Disease
Insects of concern include armyworms, bulb mites, click beetles, cutworms, leafminers, leek moths, nematodes, onion maggots, and thrips.
The onion family is vulnerable to a number of diseases from leaf blight, fusarium basal rot, and purple blotch to black mold, slippery skin, and smudge.
Many of these maladies are not among the most common threats to bunched onions, though green onions are susceptible to common diseases such as bacterial soft rot, bulb rot, damping off, downy mildew, grey mold, onion yellow dwarf virus, rust, smut, Southern blight, twister, white tip, and wilt.
Storage & Packaging
Recommended storage temperature is 32°F with high humidity (95 to 100%) to maintain moisture, color, and overall quality. Green onions are sensitive to ethylene and should be separated from producers; additionally, they can emit their own odor, which can be harmful to the flavor of other fruits and vegetables such as apples, corn, grapes, mushrooms, and rhubarb.
References: North Carolina State Extension, Oregon State University, U.S. Food & Drug Administration/University of California, Davis Western Institute for Food Safety & Security.
GRADES & GOOD ARRIVAL
There are two grades for green (bunched) onions, U.S. No. 1 and U.S. No. 2. For U.S. No. 1, product should be fairly well-formed, firm, tender, clean, free from decay, and free from damage caused by seed stems, roots, foreign material, disease, insects, and injury.
Bulbs should be well trimmed and tops fresh, green, unbroken, and free of bruising. Bunches should have uniform clipped tops. Overall length should be from 8 to 24 inches and diameter from one-quarter to 1 full inch.
For U.S. No. 2 green onions, product should not be badly misshapen, fairly firm, tender, clean, free from decay and from serious damage.
Bulbs shall be fairly well trimmed, green, and free from serious damage. Length shall be not less than 8 inches and diameter not less than one-quarter inch or more than
Generally speaking, the percentage of defects shown on a timely government inspection certificate should not exceed the percentage of allowable defects, provided: (1) transportation conditions were normal; (2) the USDA or CFIA inspection was timely; and (3) the entire lot was inspected.
|U.S. Grade Standards||Days Since Shipment||% of Defects Allowed||Optimum Transit Temp. (°F)|
There are no good arrival guidelines for this commodity specific to Canada; U.S. guidelines apply to shipments unless otherwise agreed by contract.
References: DRC, PACA, USDA.
• Green onions shall be not more than 24 inches nor less than 8 inches in length
• Diameter shall not be less than .25 inches or more than 1 inch
• Green onions can be affected by various types of discoloration from yellowing to tan to light brown; score discoloration as damage when affecting an aggregate area of more than 20% of the leaves, or when materially affecting the appearance
• Decay may affect the tops as well as the bulbs and any amount is scorable against the 2% tolerance for decay.
Source: Tom Yawman, International Produce Training, www.ipt.us.com.