years. Because onions are shallow rooted and weakcompetitors with other plants, avoid sites withhistories of perennial weeds, particularly Bermudagrass and nutsedge.

Soil preparation should begin four to six weeks priorto planting by shredding any litter on the surface anddeep turning the soil. Just before planting, rototill thesoil to form a smooth, firm surface for planting. This isa good time to incorporate preplant fertilizers. The soilmay require irrigation to achieve uniform moisturebefore seeding onions. Do not plant into a dry seedbed.

FERTILIZER AND LIME

Onions are heavy feeders and require a considerableamount of fertilizer, particularly nitrogen. However,because green onions are harvested before reachingmaturity, they will not require as much fertilizer as drybulb onions.

Nitrogen (N) is important for proper foliage growthand good green color. At least 25 percent of thenitrogen applied should be in the nitrate form becausehigh rates of ammonium-containing fertilizers can betoxic to onions. Nitrate nitrogen is readily leached byheavy rains, so apply it in small amounts in regularsidedressings.

Phosphorus (P) is important for proper root growth.It is not leachable and is usually found in ampleamounts in many soils. Availability is limited, though, incool soils, so it is best to band at least part of thephosphorus 2 inches below and 2 inches to the side ofthe seed.

Potassium (K) enhances the plant’s ability totolerate/resist disease and cold injury. Like nitrogen,potassium is easily leached from soils, particularlysandy soils; therefore, potassium may need to besidedressed in small amounts.

Sulfur (S) is essential for onion growth. As the plantuses nitrogen, it also uses sulfur to make proteins.Sulfur is also important in forming pungentcompounds. Apply 50 to 80 pounds of sulfur per acreat planting.

Micronutrients are also important in onionproduction. Apply 1 pound per acre of boron (B) and 5pounds of zinc (Zn) per acre.

In one method of fertilization, nitrogen may beapplied in a split application with all of the phosphorusand potassium applied preplant. Typically, 800 to1,000 pounds of 5-10-15 (with 5 percent sulfur) isapplied preplant and incorporated. In addition, 100 to150 pounds of 10-34-0 should be applied after seedingto help establish the new planting.

Sidedress with a nitrogen fertilizer such as calciumnitrate or sodium nitrate when plants are 3 to 4 inchestall. A second sidedress may be needed three to fiveweeks later depending on when the onions will beharvested or if there have been leaching rains.

PLANTING

Transplanting is a more dependable method ofgetting a stand than direct seeding. Vidalia greenonions are transplanted or direct seeded; scallions areusually direct seeded. Locally grown plants should beused when available to avoid introduction of diseasessuch as pink root.

To grow transplants, space rows 9 to 14 inchesapart and sow seed at 20 to 30 pounds per acre. Theseeding rate should be 60 to 70 seeds per linear foot.Plants should be ready to transplant in the field 45 to65 days after sowing. A properly grown transplant willbe about ¼ inch in diameter. After pulling thetransplants, trim the roots to ¼ inch and the tops to 4to 6 inches. Transplant only strong, disease-free plantsto insure a healthy, uniform harvest of high qualitygreen onions.

Set plants 2 inches deep into a moist, well-preparedbed. Irrigate immediately after transplanting (pegging)to settle the soil around the plants. Transplantedonions require one to two weeks longer than directseeded onions to reach harvest.

Green onions are seeded in the fall and late winter orearly spring. Fall seeding begins in August andcontinues into early October. Spring and summer croponions can be seeded from January into April. Greenonion crops seeded in late winter (January andFebruary) run a greater risk of being killed by freezingweather. Onions sown in late February or March havethe best chance of producing a spring crop of greenonions under average conditions. Most of Georgia’sgreen onions, particularly Vidalia onions, are grown asa fall crop. Successive crops can be planted at two- tothree-week intervals to provide a continuous supply.

Final row spacing for transplants or direct-seededonions will vary from 9 to 24 inches. A commonspacing would be four rows, 14 inches apart on a6-foot-wide bed. In-row spacing would depend on thetype of onion to be grown. Seed the smaller,scallion-type (long-day) onions at 21 to 27 seeds perfoot to get a final spacing of 12 to 15 plants per foot ofrow. This will require 5 to 8 pounds of seed per acrefor four rows per bed, 7 to 12 pounds of seed per acreat six rows per 6-foot-wide bed.

For the larger Vidalia onions, halve the seedingrate to give a 2 inch in-row spacing or a final plantpopulation of about 120,000 plants per acre on fourrows on a 6-foot bed. You can increase the numberof plants per acre, as with scallions, by using five orsix rows per bed. Place transplants 2 to 4 inchesapart in the row. Management of fertility anddisease must be more exacting when growing onnarrow row spacings.

When seeding during hot weather, the beds must bekept moist to insure proper germination and to preventstress on the plants. This means that beds may haveto be irrigated several times a day with 0.1 to 0.2

inches of water. After three weeks, irrigation can becut back to about ½ to ¾ inch of water twice a week.

WEED CONTROL

Weed control is vital to producing high qualityonions. Onions compete poorly with weeds, so weedscan drastically reduce yield and quality. Weeds makethe onion crop harder to harvest and can make otherpest-control measures less effective. There areseveral options for weed control.

Cultivation is difficult in onions because of theirshallow root system. Cultivate shallowly early in theseason but avoid throwing extra soil around the plants.Cultivations can be combined with fertilizerapplications (sidedressing) and can improve aerationafter heavy rains. Avoid late cultivation because it willcut roots and break the foliage.

Chemical weed control probably offers the mostefficient and effective method of control, particularlyfor large plantings. The latest edition of the GeorgiaPest Control Handbook or your local countyExtension agent should be consulted for the latestinformation on the use of herbicides in onions. Careshould be exercised in the use of these chemicalsbecause crop damage is a real danger if rates arenot followed exactly. In addition, care should betaken to prevent injury to adjacent crops and toavoid polluting the environment.

DISEASES

Onion diseases are best controlled by using goodcultural practices and resistant varieties along with agood spray program. Consult the latest edition of theGeorgia Pest Control Handbook or your local countyExtension agent for the latest methods on controllingdiseases.

With green onions, consumers eat the foliage alongwith the bulbs. This means that harvest intervals (thetime from the last spray to harvest) may be longer thanin dry bulb onion production. Consult the label todetermine harvest intervals for chemicals and followthese exactly. Failure to follow these guidelines mayresult in condemnation of your crop.

INSECTS

Seed-corn maggots and onion thrips are the twomajor insect pests of onions. Controlrecommendations can be found in the Georgia Pest

Control Handbook. Be careful to observe all safetyprecautions and harvest intervals.

COLD AND WIND DAMAGE

Cold damage may appear as a discoloration of thefoliage, wrinkling of the leaf tissue or, in severe cases,actual wet spots where the cells have ruptured due toice formation. Susceptibility to cold is determined byvariety and cultural practices, especially fertilization.Heavy nitrogen fertilization can make onions moresusceptible to cold injury. Adequate potassium helpsonion plants better withstand injurious cold.

A silver streak on one side of the onion foliage isgood evidence of wind damage. Wind damage is oftenassociated with abrasion caused by wind-blown sandparticles. Plant small grain windbreaks every 10 bedsto reduce this damage.

HARVEST

Green onions are harvested when they reach theproper diameter for the particular market. For example,scallions are usually from ¼ to 5/8 inches in diameter orlarger at harvest. This can be from 60 to 90 days afterseeding, depending on the variety and the season. Thelarger Vidalia onions are typically harvested when thebulb is 1 inch or larger. Be careful during harvest toprevent damage to the onions, especially the tops.

Tops are usually clipped to 12 inches for scallionswhereas Vidalia onions are often sold with unclippedtops. Scallions are banded together with 12 to abunch. Vidalia green onions are banded three to six toa bunch. Boxes are packed with two or four dozenbunches for shipping, often in wax boxes with opentops for top icing. Check with your buyers or potentialmarkets for their requirements on packaging.

After harvesting, reduce field heat as quickly aspossible by icing to cool onions to 40°F. About 2.2pounds of ice is required for every 4 pounds ofproduce to achieve proper cooling. Hold green onionsat 32° to 34°F and 95 percent to 100 percent relativehumidity for best storage life. Top icing is advisable,especially during transport. Storing onions at highertemperatures causes a slimy rot of the foliage. Underthe best conditions, green onions will only store forthree weeks, so get them to market as soon afterharvest as possible. For more information onpostharvest handling, consult Extension Bulletin 971,Handling, Packing, and Cooling Quality Vegetables.

Appreciation is expressed to Wayne McLaurin, Extension Horticulturist; Willie O. Chance III, Extension Agent;David Adams, Extension Entomologist; Reid Torrence, CEC Tattnall County; Rick Hartley, Former CEC ToombsCounty; and the Vidalia Onion Committee for their contributions to this publication.

Bulletin 821 Reviewed April, 2009

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