Begin Planting Onions In Late September Advises LSU AgCenter Horticulturist

Thomas J. Koske  |  4/19/2005 10:28:28 PM

News You Can Use For September 2004 

Bulbing onions and other such allium crops, like the bulbing shallot, are good long-season occupants of Louisiana winter gardens. "Get a timely start and plant seed late September to early October," says LSU AgCenter horticulturist Dr. Tom Koske.

Bulbing alliums can be grown from seed, transplants or sets, according to the LSU AgCenter horticulturist, but he cautions not to plant onion sets or transplants before December. "To do so should cause the onions to bolt and flower early or even fail to set proper bulbs," Koske says.

The leek resembles the onion in its cultural requirements. Instead of forming a large bulb, it produces a thick, fleshy cylinder, like a large green onion. Because the flavor is mild, Koske says many people use it as a preferred substitute for green onions. Leek seeds are planted in September though December and require about 120-150 days to mature. If transplanted, however, leek plants require only 80 to 90 days to mature. Seed allium bulb crops like onions and bulbing shallot two months before transplants are needed.

Koske says for large, food-quality bulbs, vigorous and continuous shoot growth is necessary. On soils of average fertility, work about 3 or 4 pounds of an 8-24-24 fertilizer or 7 to 8 pounds of 8-8-8 fertilizer into each 100-foot row a week or two before transplanting. Sidedress the row with about 3/4 pound of ammonium nitrate per 100 feet of row monthly to maintain strong top growth.

Shallot bulbs or transplants, as well as garlic cloves, may be set in the soil during October and November. Clove ‘toes’ are different from the small, hard-shell, flat-sided offset corms. These corms will grow into garlic, but will not develop cloven heads; these heads are solid and just fine to eat.

Fertility for all these alliums can be considered the same. Sidedress 100-foot rows with 1/2 pound ammonium nitrate or 3/4 pound ammonium sulfate in high pH soils monthly to keep up good strong growth. Nice shallot bulbs were produced in Baton Rouge and Hammond from true seed of Matador and Prisma cultivars.

Onion plants should be transplanted in December or January, spacing the plants about 4 inches apart in the row. A double row may be planted on a garden bed. Be sure to keep the plant beds free from weeds by hand-pulling or by very shallow cultivation. Onions do not compete well against weeds.

Koske points out that choosing a variety of onion is very important, because not all varieties were bred for Louisiana’s "short day" conditions. Many onion failures can be traced back to buying transplants of questionable variety. The horticulturist says several popular and desirable varieties are available for Louisiana conditions.

For red onions, the Red Creole and Creole C5 are popular selections. These are medium-small, pungent and store well. Red Burgundy produces a medium, mild bulb.

For white onions, the Crystal Wax is popular. It is a medium-size mild Bermuda type, also used for bunching onions. Super Star is a new All-American Selection.

Yellow onions are gardeners’ most popular choices. Granex 33 is the early Texas hybrid grown in Vidalia, Georgia. Texas Grano 1015Y Aggie Sweet produces a large, mild bulb that is very sweet under the right growing and soil conditions. The Texas Grano 502 is well known for large, mild bulbs with fair storage potential.

Koske says most pest problems will be able to be controlled with sprays of malathion for insects and maneb for diseases. Be sure to follow the label advice. Onions require minimal care and can be stored for long periods of time after the late spring harvest.

For related topics, look for Gardening and Get It Growing links in the Feature section of the LSU AgCenter Web site:  Additional yard and garden topics are available from an extension agent in your parish LSU AgCenter office.


On the Internet: LSU AgCenter:
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Source: Tom Koske (225) 578-2222, or

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