Yellow Granex Onion
Allium cepa 'Yellow Granex'
The authentic sweet onion that made Georgia's Vidalia region famous, Yellow Granex produces large, globe-shaped bulbs with exceptionally mild, sweet flavor. These golden beauties are so gentle they can be eaten like apples when grown in the right conditions. Perfect for gardeners wanting to grow their own version of premium sweet onions.
Harvest
110-120d
Days to harvest
Sun
Full sun
Zones
5–10
USDA hardiness
Height
12-18 inches
Planting Timeline
Showing dates for Yellow Granex Onion in USDA Zone 7
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Yellow Granex Onion · Zones 5–10
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | — | — | May – June | August – October |
| Zone 4 | — | — | April – June | August – October |
| Zone 5 | — | — | April – May | August – November |
| Zone 6 | — | — | April – May | July – November |
| Zone 7 | — | — | March – May | July – November |
| Zone 8 | — | — | March – April | June – December |
| Zone 9 | — | — | February – March | May – December |
| Zone 10 | — | — | January – March | May – December |
Complete Growing Guide
Light: Full sun (6 or more hours of direct sunlight a day). Soil: High Organic Matter, Loam (Silt), Sand. Soil pH: Alkaline (>8.0), Neutral (6.0-8.0). Drainage: Good Drainage, Moist. Height: 1 ft. 0 in. - 1 ft. 6 in.. Spread: 0 ft. 6 in. - 1 ft. 0 in.. Spacing: Less than 12 inches, 12 inches-3 feet. Maintenance: Medium. Regions: Coastal, Mountains, Piedmont.
Harvesting
Flowers wither and convert to bulblets
Type: Capsule.
Harvest time: Summer
Bloom time: Summer
Storage & Preservation
Yellow Granex onions are designed for fresh consumption rather than long-term storage, typically keeping 2-4 weeks when properly cured. After harvest, cure bulbs in a warm (80-85°F), well-ventilated area for 2-3 weeks until outer skins become papery and necks feel completely dry. Store cured onions in a cool (45-55°F), dry location with good air circulation, checking regularly and using any that show signs of sprouting or soft spots first.
For longer preservation, Yellow Granex onions excel when caramelized and frozen in portion-sized containers, maintaining their sweet flavor for up to 8 months. They can also be sliced and dehydrated at 135°F for 6-12 hours until crisp, creating sweet onion flakes perfect for seasoning. Pickling is another excellent option—their mild flavor makes exceptional refrigerator pickles that keep for 2-3 months. Avoid traditional root cellar storage methods, as these sweet onions lack the sulfur compounds needed for extended fresh storage.
History & Origin
Yellow Granex was developed in the 1930s by agricultural researchers at the University of Georgia as part of an effort to create an onion variety perfectly suited to Georgia's unique soil and climate conditions. The variety was specifically bred to thrive in the low-sulfur soils of the Vidalia region, where the lack of sulfur compounds allows the onion's natural sugars to dominate, creating the famously sweet flavor profile.
This hybrid became the foundation onion for what would eventually become the protected Vidalia onion designation in 1986, when Georgia passed laws restricting the use of the 'Vidalia' name to onions grown in specific counties with the right soil conditions. The development of Yellow Granex represented a breakthrough in onion breeding, proving that environmental factors could be matched with genetic traits to produce consistently mild, sweet bulbs.
Today, Yellow Granex remains the primary variety grown in Georgia's Vidalia region and has become the gold standard for sweet onions nationwide. Home gardeners outside Georgia can grow genetically identical onions, though the flavor may vary depending on local soil sulfur content and growing conditions. The variety's success helped establish the concept of terroir in American vegetable production.
Advantages
- +Disease resistance: Black Walnut, Deer, Rabbits
Considerations
- -Toxic: Low severity
Companion Plants
Plant Together
Carrots
Onions repel carrot flies while carrots help break up soil for onion bulb development
Tomatoes
Onions deter aphids, hornworms, and other tomato pests while improving tomato flavor
Cabbage
Onions repel cabbage worms, flea beetles, and other brassica pests
Lettuce
Onions provide natural pest protection while lettuce acts as living mulch
Broccoli
Onions deter cabbage loopers and aphids that commonly attack brassicas
Peppers
Onions repel aphids and spider mites while peppers don't compete for nutrients
Strawberries
Onions deter slugs, aphids, and other soft-bodied pests that damage strawberry plants
Marigolds
Both repel nematodes and various garden pests through natural compounds
Keep Apart
Beans
Beans and other legumes can inhibit onion growth and bulb development
Peas
Legumes can stunt onion growth through root competition and nitrogen interference
Asparagus
Onions can inhibit asparagus growth and both compete for similar soil nutrients
Nutrition Facts
Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #170000)
Pests & Disease Resistance
Resistance
Good resistance to pink root and fusarium basal rot
Common Pests
Onion thrips, onion maggots, cutworms
Diseases
Downy mildew, purple blotch, neck rot