Georgia sits at latitude 33.63 degrees north, and on the longest day of the year the sun gives it 14 hours and 14 minutes of daylight. That single fact decides which onions will actually form a bulb in a Georgia garden and which ones will simply grow leaves until they rot. Here’s how to read it, variety by variety.
How long your longest day is
Atlanta’s 33.63°N and its 14-hour-14-minute summer solstice day put Georgia squarely in short-day and intermediate-day onion territory. Onions don’t bulb because of heat or soil richness. They bulb because of day length. Clemson Cooperative Extension’s Home & Garden Information Center puts the trigger for short-day types at roughly 12 hours of daylight, a threshold Georgia clears easily and early in the season. Intermediate-day types need something closer to 13 to 14 hours, which Georgia’s summer also supplies. Long-day onions, the ones that need 14 to 16 hours before they’ll switch from leaf-making to bulb-making, are a different story. Georgia’s longest day tops out at 14:14, and for many long-day varieties that’s not enough, or barely enough, and only for a few weeks a year rather than the sustained stretch those onions actually need.
So the whole logic of this page comes down to one paragraph: grow short-day or intermediate-day onions in Georgia, skip long-day onions entirely, and treat anything close to the edge of a range with caution rather than certainty. Everything below is detail on top of that.
One caveat matters here. Georgia is a big state, and 33.63°N is the latitude of Atlanta specifically, not of Savannah, Dalton, or Valdosta. The state spans several degrees of latitude from the Tennessee line to the Florida border, and daylight hours shift with it. A gardener in the far north of the state, up near Chattanooga’s latitude, gets a slightly longer summer day than someone in Atlanta. A gardener down near the Okefenokee gets a slightly shorter one. It’s not a dramatic swing, but if your yard sits near either edge of the state, it’s worth checking your own latitude rather than assuming Atlanta’s numbers apply exactly to you. The general rule holds across the whole state either way: this is short-day and intermediate-day country, full stop.
Which varieties bulb in Georgia
Twelve varieties documented on this site have a published latitude range that covers 33.63°N, meaning Georgia sits comfortably inside their intended growing zone rather than at some marginal edge. These are the ones to plant with confidence:
- Candy (intermediate-day, 33-40N)
- Elsye (intermediate-day, 32-45N)
- Expression (intermediate-day, 32-45N)
- Gabriella (short-day, 20-35N)
- Madalyn (short-day, 20-35N)
- Red Rock (short-day, 30-36N)
- Red Sensation (short-day, 25-35N)
- Scout (intermediate-day, 32-46N)
- Sierra Blanca (intermediate-day, 32-45N)
- Texas Grano 1015Y (short-day, 25-35N)
- Vidora (short-day, 25-35N)
- White Castle (short-day, 30-38N)
Six more varieties sit within about a degree and a half of a published boundary, which puts them in a blurred zone rather than a clear yes. Bridger, Walla Walla Sweet, Cabernet, Calibra, Monastrell, and Red Long of Tropea all list ranges that start at 35°N, close enough to Georgia’s 33.63°N that they may bulb here, particularly in the northern part of the state, but they’re a gamble rather than a sure thing. Treat them as an experiment, not a main crop.
The varieties that will not work here
This is the part of the page that matters most, because it’s the mistake gardeners actually make. Thirteen documented varieties are published for latitudes well above Georgia, and none of them will bulb here:
- Ailsa Craig (long-day, 38-60N)
- Barolo (long-day, 38-55N)
- Blush (long-day, 38-55N)
- Frontier (long-day, 40-50N)
- New York Early (long-day, 38-50N)
- Patterson (long-day, 38-55N)
- Powell (long-day, 43-47N)
- Red Carpet (long-day, 40-45N)
- Red Long of Florence (intermediate-day, 38-50N)
- Redwing (long-day, 43-65N)
- Rossa di Milano (long-day, 38-50N)
- Safrane (long-day, 42-50N)
- Talon (long-day, 42-50N)
If any of these sound familiar, it’s probably because they’re common in seed racks and mail-order catalogs that ship nationwide without adjusting for where the buyer actually gardens. Plant one in Georgia and here’s what happens: the plant grows lush green tops all spring, looks perfectly healthy, and then, right around when a Georgia gardener expects to be harvesting, it just keeps making leaves. No swelling at the base, no bulb forming. Eventually the plant weakens, the neck softens, and it rots in the ground or in storage. It’s not a smaller onion. It’s no onion. If that description matches something you’ve already been through with a supermarket set, you now know why.
When to plant onions in Georgia
Because Georgia falls in the short-day and intermediate-day camp, its onion calendar looks nothing like the spring-planting schedule used across the northern half of the country. In mild-winter regions like this one, onions typically go in the ground in fall, overwinter as small plants, and then bulb up as day length increases the following spring and early summer.
The frost window frames that timing. Atlanta’s average first fall frost falls between November 13 and December 1, and the average last spring frost falls between March 11 and March 29, based on NOAA’s 1991-2020 climate normals for freeze probability. Fall-planted onion sets or transplants generally go in a few weeks before that first frost window, giving roots time to establish while the plant stays small and unbothered by the cold. Come late winter, as the days lengthen back past that 12-hour mark, the same short-day varieties that sat quietly all winter start pushing into bulb production well ahead of the spring-planted crops grown farther north.
Two things to keep in mind about those frost dates. First, they’re averages built from three decades of data at the Atlanta airport station, not a guarantee for any single year, and definitely not a promise for your particular yard. Second, Atlanta’s airport sits in an urban heat island, which runs warmer than the surrounding countryside. North Georgia and the mountains typically see their first fall freeze several weeks earlier than Atlanta does, while the coastal plain down toward Savannah and Valdosta tends to run milder and later. A gardener in Blue Ridge or Dahlonega should plan around an earlier fall frost than the Atlanta figures suggest, and a gardener near the coast has more room to push planting later into fall.
Sweet onions or onions that keep
Georgia’s climate hands its gardeners a specific kind of onion, and it’s worth understanding why before you decide what to grow. University of Missouri Extension puts it plainly: sweet onions do not store as well as pungent types. That’s not marketing language, it’s chemistry. The bite in a pungent onion comes from volatile sulfur compounds, and those same compounds are what protect the bulb once it’s out of the ground, slowing the rot and sprouting that eventually take down every stored onion. A sweet variety has fewer of those compounds. That makes it milder and better eaten fresh, but it also means it has less built-in protection, and it won’t hold up in a pantry or root cellar for more than a few weeks to a couple of months.
This lines up with the day-length pattern that runs through this whole page. Short-day varieties, the ones that dominate Georgia’s growing conditions, tend to run sweeter and shorter-keeping. Long-day varieties, grown farther north where summer days stretch past 14 or 15 hours, tend to run sharper and store longer, sometimes well into the following spring. It’s not a coincidence and it’s not a matter of skill. It’s the same trait doing two jobs: fewer sulfur compounds means a milder onion at the table and a shorter shelf life in storage, and Georgia’s short-day varieties sit on the sweet, short-keeping end of that spectrum almost across the board.
Practically, that means a Georgia gardener growing Candy, Vidora, Texas Grano 1015Y, or any of the other short-day varieties on this page should plan to eat most of the harvest within a few months of pulling it, not stretch it toward the following year. Nobody should promise themselves a Georgia-grown onion that’s still firm and mild in March. Onions that grown-in-Georgia would still be firm and flavorful that far into the year would need to come out of long-term storage handling, or from a variety grown somewhere with a longer summer day and a sharper, tougher bulb to show for it.