Cooperative Extension Service 
Institute of Food and Agricultural Sciences
Hendry County Extension, P.O. Box 68, LaBelle, Florida 33975-0068  Phone (863) 674-4092

Hendry County Horticulture News

Onions - Sweet Onions

Sweet "Vidalia" onions have become very popular over the past few years.  These sweet, large bulbed onions are produced in the vicinity of Vidalia, Georgia.  Sweet onions are characterized by a low level of strongly pungent sulfur compounds.

The "Vidalia" onion became popular as the result of an imaginative marketing campaign by commercial onion growers in the area of Vidalia, to increase the sale of their sweet onions.  Their strategy was so successful that "Vidalia" has become a household word and now sustains the production of some 6000 acres of sweet onion in this region of Georgia.  So profitable has this industry become that the Georgia legislature has trademarked the name and has established certain mandatory guidelines for the production of this crop.  To be marketed as a true "Vidalia," an onion must be grown in the Vidalia area and conform to the Yellow-Granex type.

So what is so special about "Vidalia" onions?  In a word-nothing, but a very clever sales promotion.  The Granex-type of onion, along with the old Texas Grano are short day varieties that do well under Florida conditions.  This type of onion is typified by the Granex 33 strain.  Granex 33 has been the standard recommended onion variety for farm and garden in our state for many years.  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 proper "Vidalia."

This is good news for local gardeners, who wish to produce their own sweet onions.  Gardeners, 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 as onion seed declines rapidly and seed even a year old 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.  Remember that wider spacing and good fertility will yield larger bulbs.  In the absence of a soil test the garden should be fertilized with a broadcast application of 2 ½ 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.  Onions are shallow rooted, so remember to irrigate frequently to keep the soli moist and promote steady growth.  Inconsistent watering may lead to splits and the production of doubles and small bulbs.  Side dress the crop monthly with a nitrogen fertilizer at the rate of ½-1 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 easily be taken over by weeds and yields reduced. Begin disease control efforts early before diseases become established.  Leaf blights can seriously reduce yields.  Monitor at least twice weekly for insects and take appropriate control measures.  Contact the Hendry County Extension Office for more information on pest and disease control recommendations.

Bulb onions take 120 -160 days 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 Granex-type onions are not noted for their storage qualities.

So if you like sweet onions, get out there and grow your own.  While they may not be legally labeled "Vidalia," they will be every bit as good.

(Parts extracted from Stephens, UF/IFAS Vegetarian Newsletter, 97-09)

Gene McAvoy is the horticulture agent with the Hendry County Extension Service.  Direct your horticulture questions to PO Box 68, LaBelle, FL 33975,  e-mail - or phone 863-674-4092 or 863-983-1598.  You are also welcome to visit the Hendry County Extension Office at 225 Pratt Blvd., LaBelle.   Office hours are from 8:00 - 5:00.

The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity - Affirmative Action Employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap or national origin.

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