Virginia sits close enough to the edge of two onion worlds that the safe answer is intermediate-day, not short-day and not full long-day. At Norfolk, the weather station that anchors these figures, latitude is 36.82 degrees north and the longest day of the year runs 14 hours and 32 minutes. That number decides which onions will actually make a bulb here and which ones will just sit in the ground making leaves.
The short answer for Virginia
Onions do not care how warm your soil gets. They care how long the sun stays up. Bulbing switches on once day length crosses a variety’s threshold, and at 14 hours 32 minutes on the summer solstice, Norfolk lands squarely in intermediate-day territory, the group bred to bulb somewhere between 12 and 14 hours of daylight. That is the group most Virginia gardeners should be planting.
Nine intermediate-day varieties have published ranges that cover 36.82N: Cabernet, Calibra, Candy, Elsye, Expression, Monastrell, Red Long of Tropea, Scout, and Sierra Blanca. Any of these should size up reliably in a typical Virginia garden, whether you’re in the Tidewater flatlands or the Shenandoah Valley.
Two long-day varieties also list ranges that dip low enough to include this latitude: Bridger (35-50N) and Walla Walla Sweet (35-55N). Because their range starts right at the edge, they’ll bulb here, but they’re working near the bottom of their comfort zone rather than the middle of it, the way the intermediate-day group is. One short-day variety, White Castle (30-38N), also covers this latitude on paper, though it has no dedicated page on this site.
The practical takeaway: build your onion patch around the intermediate-day list first, add a long-day variety or two if you want something that keeps into winter, and treat short-day types as a southern Virginia experiment at best, not a statewide default.
What will not work here
This is the part seed racks rarely explain, and it’s the difference between a harvest and a wasted season. Day length is not a suggestion for an onion. It’s a switch. Plant the wrong group and the plant does not “struggle,” it does something specific and predictable.
Short-day varieties bred for latitudes well south of Virginia will start bulbing the moment day length hits their low threshold, around 12 hours, which happens here in early spring while the plant is still small. The bulb that forms is whatever size the plant had reached by that point, permanently. No amount of extra feeding or extra weeks in the ground fixes it, because the plant has already stopped building leaf mass and started closing off the bulb.
- Gabriella (short-day, 20-35N): bulbs while still juvenile here, yields a marble-sized onion at best
- Madalyn (short-day, 20-35N): same early-trigger problem, undersized bulbs
- Red Sensation (short-day, 25-35N): bulbs too early for Virginia’s day length, small yield
- Texas Grano 1015Y (short-day, 25-35N): bred for Gulf Coast latitudes, bulbs prematurely here
- Vidora (short-day, 25-35N): same mismatch, small bulbs regardless of care
Long-day varieties bred for the far north fail in the opposite direction, and it’s worse. Their threshold, 14 to 16 hours, never arrives here even on the solstice. The plant keeps making leaves all summer because nothing ever tells it to stop, then the top dies back with the season and the neglected bulb, such as it is, rots in wet fall soil.
- Frontier (long-day, 40-50N): day length here never reaches its trigger
- Powell (long-day, 43-47N): built for latitudes far north of Virginia, no bulb forms
- Red Carpet (long-day, 40-45N): threshold unreachable at 36.82N
- Redwing (long-day, 43-65N): a northern-tier onion, all leaf here, no bulb
- Safrane (long-day, 42-50N): same story, leaves then rot
- Talon (long-day, 42-50N): day length maxes out below its requirement
What changes across Virginia
Virginia is not one climate, and it’s not one latitude either. The state runs roughly from about 36.5 degrees north at Virginia Beach to nearly 39.5 degrees north up near the Maryland line, a spread of almost three full degrees. That’s enough room for the advice above to shift depending on which end of the state you garden in.
| Region | Approximate latitude | What it changes |
|---|---|---|
| Southern/Coastal VA (Virginia Beach, Norfolk) | ~36.5-37N | Matches the reference figures closely. Intermediate-day varieties are the clear default; short-day types remain too small to bother with. |
| Northern VA (near DC border, Loudoun/Fairfax counties) | ~38.5-39.5N | Days run modestly longer than at Norfolk. Several blurred-zone long-day varieties shift from “may bulb” to “likely bulb,” while short-day varieties become even more clearly excluded. |
That northern edge is where the blurred-zone varieties come into play: Ailsa Craig, Barolo, Blush, New York Early, Patterson, Red Long of Florence, and Rossa di Milano all publish lower bounds around 38N, within a degree and a half of the state’s northern counties. These are not a flat yes. A gardener in Loudoun County is close enough to that threshold that the variety may bulb well in a warm, long-daylight year and disappoint in a cooler one. A gardener down in Virginia Beach is too far south for most of them to be worth the risk. If you garden near either edge of the state, check your own latitude rather than assuming Norfolk’s numbers apply to you.
Sweet now, or onions that last
Every onion gardener eventually runs into the same trade, and it’s chemistry, not luck. The volatile sulfur compounds that make an onion bite your eyes and sting your tongue are the same compounds that protect the bulb from breaking down in storage. Breed the sulfur out for a milder, sweeter onion and you also breed out its ability to keep. According to University of Missouri Extension, “as a rule, ‘sweet’ onions do not store as well as the more pungent types.”
Day length lines up with this trade almost perfectly. Short-day and intermediate-day onions, the kind that thrive in warmer, shorter-summer-day latitudes, tend to run sweeter and milder because they were never selected for winter storage in the first place. Long-day onions, grown where summers stay cooler and days stretch longer, tend to run sharper and keep for months because that sharpness was the point.
Virginia’s position squarely in intermediate-day country means most of the varieties suited to the state, Candy, Sierra Blanca, Elsye, lean toward the sweet, eat-it-soon side of that spectrum. That’s a fine trade if you’re cooking through the harvest in real time, but it means your March pantry probably won’t have much onion left in it unless you deliberately grow one of the long-day options, Bridger or Walla Walla Sweet, that also cover this latitude and hold longer once cured.
Checking this against your own garden
Everything above comes from a single reference point, Norfolk’s station data, and Virginia is too long a state for one city’s numbers to speak for every backyard in it. Before you commit to a variety list, spend a few minutes confirming where your own garden actually sits.
- Look up your own latitude if you garden more than an hour’s drive from Norfolk, especially anywhere near the Maryland line or in the far southwest corner of the state
- Check your local average last spring frost date and first fall frost date, since these determine when you can safely set out transplants or sets
- Call or visit your county’s Virginia Cooperative Extension office, which tracks variety performance and frost data specific to your county rather than a statewide average
- Note your garden’s microclimate, a south-facing slope or a low frost pocket can shift your effective planting window by a couple of weeks either direction
- If you’re within a degree or two of 38N, treat the blurred-zone long-day varieties as a trial planting rather than your main crop until you’ve seen how they perform in your soil