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Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

The Other Onions

This article was published originally on 5/9/2003

The common garden onion (Allium cepa) is one of many edible onions. These other edible onions often produce more than one bulb per growing season. Some are perennials in the garden. The common names used for these edible onions can be confusing. Almost any onion that is grown for its green tops can be called bunching onions, scallions, or shallots. In addition, almost any onion that produces clusters of small underground or aboveground bulbs can be called multiplier onions. And finally, any onion that over winters well can be called a winter onion. Below is a brief description of several edible onions (including more common names) that can be grown in Iowa gardens.

Welsh onions (Allium fistulosum) are also called green onions or Japanese onions. Because Welsh onions don t typically produce a bulb, they are primarily grown for their green tops. Sow seed in early spring for harvest in summer. A second sowing in mid summer can be harvested in fall or the following spring. Plants are hardy and one of the first to emerge in spring. Egyptian onions (Allium cepa proliferum) are also called tree onions, walking onions, or top-setting onions. These onions do not flower like other onions. Small clusters of reddish, marble-sized bulbs (bulbils) are produced at the tops of the leaves instead of flowers or seed. As these bulbils increase in size and weight the leaves bend to the ground and the bulbils take root. This allows the plant to walk around the garden. The tops, underground bulbs, and bulbils are all edible. However, many people prefer to eat only the green tops and immature bulbils because both the bulbs and mature bulbils can be very pungent. Egyptian onion is very cold hardy and the bulbs generally survive the winter. Plant bulbs in early spring or plant bulbils in fall for overwintering.

Shallots (Allium cepa aggregatum) are another edible onion that produce 1-inch-diameter bulbs. Because the bulbs are so small, shallots are grown primarily for the delicate flavor of the green tops. Shallot sets can be planted in spring and the green tops can be harvested any time after reaching 6 to 8 inches tall. Bulbs are not reliably hardy to many parts of Iowa. Dig up the bulbs when the foliage dies back and store indoors over the winter until replanting in spring.

Potato onions (Allium cepa aggregatum) are similar to shallots except they produce moderate-sized bulb clusters. Bulbs are planted in spring and often harvested in late summer or fall. After harvest, bulb clusters can be divided and eaten fresh, stored for winter use, or replanted the following spring. Bulbs left in the ground in fall should be mulched heavily over the winter because they are marginally cold hardy.

Chives (Allium schoenoprasum) or Garlic Chives (Allium tuberosum) are typically considered herbs instead of vegetables like other onions. The young leaves have a mild onion-like flavor and can be harvested any time during the growing season. Chives are perennials that return with vigor every year. Plant seed or divisions in early spring. Divide and dig plants frequently for best performance and to control aggressive growth.

Leeks (Allium ameloprasum or Allium porrum) do not produce true bulbs. Instead, plants are grown for their edible, thickened stems or stalks. Leeks have a milder flavor than most bulbous onions. Plant seed or transplants in early spring to harvest as green onions in summer or wait to harvest larger plants in fall. Mound a few inches of soil around the base of the plants as they grow to produce a larger, white, tender leaf base. To extend harvest into late fall or early winter, mound several inches of straw around the base of plants to prevent the ground from freezing. Leeks are nonhardy biennials that are treated as annuals in Iowa gardens.

This article originally appeared in the 5/9/2003 issue.

Year of Publication: 
IC-489(10) -- May 9, 2003