UF/IFAS Okeechobee County Extension Service

458 Highway 98 North

Okeechobee , FL 34972-2578

Phone: (863) 763-6469

E- mail:  dfculbert@ifas.ufl.edu


Quick LinksVidalia onions   Florida sweets  Home Grown Sweets   References    Parting photo

May 3, 2006

Feature Article - for release the week of May 7, 2006

Dan Culbert - Extension Horticulture Agent

Onions - Sweet Onions

Last week I was invited as a guest speaker at Disney’s EPCOT Flower & Garden Festival.  My presentation was on vegetable gardening basics, and I knew that giving away some fresh vegetables would make the talk more fun.  Since our local gardening season is winding down, I relied on a fresh supply from Georgia, where Vidalia onions are just coming into season. So for our readers who were not at EPCOT, it may be the right time to discuss this delectable southern delicacy. 

Sweet onions are available during spring and summer seasons.  They have a higher water content and lower level of the strongly pungent sulfur compounds that give cooking onions their characteristic taste and smell. Their thinner skins and looser necks mean they are more easily bruised, so their shelf life is shorter.  But their milder taste make them better suited for salads and lightly cooked foods.  

Vidalia Onions

Sweet "Vidalia" onions are sweet, large bulbed onions produced in the south-central area of Georgia.  An imaginative marketing campaign by their commercial onion growers has increased the brand name recognition and sales of their sweet onions.  "Vidalia" has become a household word, and now sustains the production of some 15,000 acres of sweet onions in this region of Georgia.  

High quality sweet onions like these Vidalias are available in produce markets in the late spring. Map courtesy Vidalia Onion Committee.

To be marketed as a "Vidalia Onion", the crop must originate in this 20-county region of South Central Georgia. Map courtesy Vidalia Onion Committee.


Onion  are not usually grown to the point of flowering in the garden unless seed production is the goal. Photo courtesy: Fabian Garcia Research Center, NMSU

The Georgia State Legislature has trademarked the name and has established certain mandatory guidelines for the production of this crop; this crop was also named Georgia’s official state vegetable in 1990.  To be sold as a "Vidalia," an onion must be grown in the 20 county area and conform to the Yellow-Granex variety specifications.  

So what is so special about "Vidalia" onions?  The Granex-types of onion, along with its old Texas Grano parent-type, are short day varieties that can also do well under Florida conditions.  Granex 33 is a typical cultivar and has been Florida’s standard recommended onion variety for farm and garden for many years.

Florida Sweet onions

Testing and research with sweet onions in the Hastings area near Saint Augustine has demonstrated that Florida grown onions could match the quality of the legal "Vidalia."  Growers in St. Augustine have been promoting St. Augustine Sweets to ride on the coat-tails of the highly successful Vidalia onion promotions.  A market advantage is that Florida could get them to market 6 weeks sooner, but local growers have had some difficulty with bulb splitting.

And in the panhandle, another entry into the sweet ring onion market appeared a few years ago: Santa Rosa Sweet was Florida's first totally pesticide-free sweet onion, grown hydroponically. (The company that was growing this product is now specializing in sea oat production for beachfront restoration work.)

Many other states grow their own “sweet” onions.  Since Florida’s production is not enough to compete with Georgia’s “Big Onion Machine”, Vidalia onions now get more consumer’s dollars than other sweet onion crops.

Local gardeners can produce their own sweet onions.  Those who wish to grow a sweet bulbing onion should select a Granex-type short day variety.  For home gardeners, seed of Granex 33 will probably be the easiest to find.  Seed should be planted in a properly fertilized plot in the fall (no later than mid-December) for best results.  Be sure to obtain fresh seed; even year-old seed may yield poor results. 

Since sulfur contributes to the pungency of onions, gardeners should avoid the application of sulfur or sulfur containing materials to the soil or plants.  Note that certain fertilizers may contain sulfur.

Onions should be planted in rows 12-24 inches apart, thinned to 4-6 inches between plants. Wider spacing and good fertility yield larger bulbs.  In the absence of a soil test the garden should be fertilized with a broadcast application of 2˝ to 5 lbs. of a general-purpose fertilizer, such as 6-6-6 .  This should be worked into the soil and a band application of 5 oz. per 10 linear feet of row applied along the side and below the row. 

Since onions are shallow rooted, irrigate frequently to keep the soil moist and promote steady growth.  Inconsistent watering may lead to splits, doubles and small bulbs.  Side dress the crop monthly with a nitrogen fertilizer at the rate of ˝-1 oz. per 10 feet of row.  Be sure to keep the fertilizer from contacting the plants directly.

Good weed control is a must.  Since young onions are small and grow slowly at first, they can be taken over by weeds that reduce yield. Consider using plastic mulch.  Look out for diseases before they become established.  Leaf blight diseases can seriously reduce yields.  Monitor for insects twice each week, and use appropriate management techniques.  Contact your local Extension Office for the latest information on pest management recommendations.

Commercial growers use plastic mulch to reduce weed problems.  Home growers may also gain benefits from using a similar system in the home garden. Photo: UF/IFAS

When 25% of the tops have naturally fallen over, this crop of Sweet Onions is ready for harvest. Photo: UF/IFAS

    For home gardeners, a short row of onions is generally all that is needed. Note this gardenr is using a raised bed.  Photo courtesy University of Nebraska

Bulb onions take 4- 5 months to mature.  A crop planted in November - December will be ready around April. The crop is ready to be harvested as the tops begin to fall over.  The onions should then be lifted and left to cure for several days in a cool dry location before removing the tops.  Curing will help increase the storage life of your crop, although don’t expect prolonged storage.

So if you like sweet onions, they are now available in the produce stands.  But come November, get out there and grow your own.  While they may not be legally labeled "Vidalia," they will be every bit as good.

I’ve placed more information about sweet onions on our Okeechobee web page, http://okeechobee.ifas.ufl.edu.  If you need additional information on, please email us at okeechobee@ifas.ufl.edu or call us at 863-763-6469.  Local residents can stop by our office at 458 Hwy 98 North in Okeechobee, and visit our Okeechobee County Master Gardeners from 1 to 5 PM on Tuesday afternoons.


Trade names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. Florida Cooperative Extension Service / IFAS / University of Florida.  Larry A.  Arrington, Dean


UF Websites:

Hochmuth, R.C. Experiences with Sweet Onions and Mulch Color in North Florida . Quincy: UF/IFAS North Florida Research & Education Center, May 2002.   http://www.hos.ufl.edu/vegetarian/02/May/May02.htm#Experiences  [Growers should not use white, white-on-black, or silver-on-black mulches for onion production in North Florida .]

Kucharek, T.  Botrytis Leaf Blight and Purple Blotch of Onions in Florida [PP-124]. Gainesville: UF/IFAS Florida Coperative Extension Service, 1/2000.  http://plantpath.ifas.ufl.edu/takextpub/FactSheets/pp0124.pdf 

McAvoy, Gene.  Onions - Sweet Onions.” LaBelle, FL: Hendry County Horticulture News, undated. http://hendry.ifas.ufl.edu/HCHortNews_Onions.htm 

Olson, Stephen M. Sweet Onion Variety Trial, Spring 2003. in  Vegetarian Newsletter. Gainesville: UF/IFAS Horticultural Sciences Department, 06/03. http://www.hos.ufl.edu/vegetarian/03/June/June.htm#Sweet 

Olsen, S. M., et.al.  Onion, Leek, and Chive Production in Florida.  [HS730] Ch.32 in Vegetable Production Guide for Florida.  Gainesville: UF/IFAS Florida Cooperative Extension Service, 12/05.  http://edis.ifas.ufl.edu/pdffiles/CV/CV12800.pdf

Stevens, Jim. Vidalia Onions. In: Vegetarian Newsletter. Gainesville: UF/IFAS Horticultural Sciences Department, 09/07

 Commercial and Industry websites:

Anonymous.  About Onions: Seasonality.  Greeley, CO: National Onion Association, 2005. http://www.onions-usa.org/about/season.asp The Vidalia Onion Committee

Vidalia Onions.  Vidalia, GA: Vidalia Onion Committee,  2006.  http://www.vidaliaonion.org/  [Information for consumers and the food industry.]

Laws: Did you know that Chumuckla, Florida, doesn't allow onions to be purchased between sunset and sunrise?   See more at ONION LAWS - fun stuff that your not supposed to do with onions!  Compiled by our friends at Texas A&M University. http://plantanswers.tamu.edu/publications/onions/onionlaws.html 

Photos: Onion production photo gallery from New Mexico State University: http://onion.nmsu.edu/General/gallery.html 

Onion Seed sources - Southern Exposure Seed ExchangeDixondale FarmsPurdue University webpage with links to commercial seed companies.

Florida Commercial Vegetable Transplant Producers http://swfrec.ifas.ufl.edu/veghort/tgrowers.htm 

Boyhan, George.  Vidalia Vegetable Newsletter [Vol. 9, #9] Statesboro, GA: East Georgia Extension Center, Georgia State University,  September 2005 [Latest newsletter] http://pubs.caes.uga.edu/caespubs/horticulture/commodityNL/vidalia-sep05.htm Archived newsletters: http://pubs.caes.uga.edu/caespubs/horticulture/commodityNL/NL-home.html  [Newsletter for commercial vegetable growers in Georgia.] 

Longbrake, Tom.  Easy Gardening - Onion.   College Station: TAMU, undated. http://aggie-horticulture.tamu.edu/extension/easygardening/onions/onions.html 

Parting Photo:

A famous onion growing area is Florida. Note the black muck soils and rolling hills. This is not in the Sunshine State, but it is in Orange County.

neatJollyOblkdirt299.JPG (24486 bytes)

Click on the photo to learn about Florida, in Orange County, or here to learn about its agricultural history.