West Virginia sits close to the line that separates the intermediate-day onion group from the long-day group, and the state’s reference point, Charleston at 38.38°N, gets about 14 hours and 41 minutes of daylight on the longest day of the year. That single fact rules half the onion catalog out before you even pick a variety. Below is what actually bulbs here, what wastes a season, and why your March pantry depends on the choice.
The short answer for West Virginia
At 38.38°N with 14 hours 41 minutes of daylight at the June solstice, Charleston-area gardens fall right on the boundary between intermediate-day onions (which bulb around 12 to 14 hours of daylight) and long-day onions (which need 14 to 16 hours). That means both groups are in play here, and it is worth planting a few of each rather than betting the whole row on one type.
On the intermediate-day side, the varieties whose published range covers this latitude include Cabernet, Calibra, Candy, Elsye, Expression, Monastrell, Red Long of Florence, Red Long of Tropea, Scout, and Sierra Blanca. These tend to bulb reliably through a West Virginia summer without waiting for the very longest days.
On the long-day side, varieties covering 38.38°N include Ailsa Craig, Barolo, Blush, Bridger, New York Early, Patterson, Rossa di Milano, and Walla Walla Sweet. These need the day to stretch closer to the 14-to-16-hour window before they’ll switch from making leaves to making a bulb, and Charleston’s 14 hours 41 minutes gets there, though not with much room to spare.
What this means in practice: a West Virginia garden is not stuck choosing between “the northern kind” and “the southern kind” of onion. It’s one of the few places where both catalogs actually work, provided you steer clear of the varieties built for latitudes this state simply doesn’t reach.
What will not work here
This is the part that saves a season. Day length here maxes out at 14 hours 41 minutes, and that ceiling is fixed no matter how good the soil is or how much you water. A variety bred for a different day-length window won’t just underperform, it will fail in a specific, predictable way.
Short-day onions are built to start bulbing at around 12 hours of daylight. Planted in West Virginia, that threshold arrives while the plant still has weeks of leaf-growing left to do further south. The bulb locks in small because the plant hasn’t had time to build size before day length tells it to stop. These are variety mistakes, not feeding mistakes, and no amount of fertilizer fixes them:
- Gabriella (short-day, published for 20-35N), bulbs far too early here and stays undersized
- Madalyn (short-day, published for 20-35N), same premature bulbing, same small onions
- Red Rock (short-day, published for 30-36N), outside its range even at the southern edge of the state
- Red Sensation (short-day, published for 25-35N), triggers well before the plant is grown
- Texas Grano 1015Y (short-day, published for 25-35N), built for a much shorter summer day
- Vidora (short-day, published for 25-35N), bulbs at 12 hours, too soon for this latitude
At the other end, some long-day varieties need more daylight than West Virginia ever provides. The day here never reaches their trigger point, so the plant just keeps making leaves all summer. There is no small onion at the end of that, because bulbing never starts, and the greens eventually rot in the ground once the season turns:
- Frontier (long-day, published for 40-50N), needs longer days than 14 hours 41 minutes provides
- Powell (long-day, published for 43-47N), well above the trigger threshold reached here
- Red Carpet (long-day, published for 40-45N), waits for a daylight peak this latitude doesn’t hit
- Redwing (long-day, published for 43-65N), built for far northern summers
- Safrane (long-day, published for 42-50N), bulbing never triggers at 38.38N
- Talon (long-day, published for 42-50N), same problem, no bulb forms
One variety sits in a gray zone: White Castle (short-day, published for 30-38N) is close enough to 38.38°N that it may bulb at the southern edge of the state, but treat it as a coin flip rather than a safe bet.
What changes across West Virginia
Charleston’s 38.38°N is a starting point, not a promise that applies from the Ohio River to the Eastern Panhandle. West Virginia runs from the southern coalfields near the Virginia border up through the Northern Panhandle, which pokes up between Pennsylvania and Ohio, a stretch of several degrees of latitude in a state most people picture as small.
That spread matters because every degree of latitude shifts the summer day-length ceiling. A garden in the southern counties sits closer to the lower edge of the long-day range for varieties like Bridger (35-50N), which makes them a safer bet there than they’d be even further north. A garden in the Northern Panhandle, on the other hand, gets more daylight at the solstice than Charleston does, which can push some of the “will not work here” long-day varieties into range.
| Location | Approximate latitude | What it changes |
|---|---|---|
| Southern WV (near Bluefield) | ~37.2°N | Slightly less summer daylight than Charleston; intermediate-day types are the surer choice, long-day varieties near their lower published bound |
| Charleston (reference city) | 38.38°N | 14 h 41 min at the solstice; both intermediate-day and long-day groups viable |
| Northern Panhandle (near Wellsburg) | ~40.6°N | More summer daylight than Charleston; varieties like Frontier (40-50N), listed as failing at 38.38°N, come into their published range here |
The takeaway isn’t that the state’s advice is wrong, it’s that “West Virginia” covers enough latitude that a gardener near either edge should treat the Charleston numbers as a reference point to check against, not a rule for their own backyard.
Sweet now, or onions that last
West Virginia’s spot on the intermediate-to-long-day boundary hands gardeners here an actual choice, and it comes down to chemistry, not luck. The compounds that give an onion its bite are volatile sulfur compounds, and those same compounds are what keep the bulb from breaking down in storage. Fewer of them, and you get a milder onion that tastes great sliced raw in July but turns soft in the pantry by October. More of them, and the onion is sharper on the cutting board but still solid in February.
The intermediate-day varieties in range here, Candy, Cabernet, Elsye, Expression, Monastrell, Scout, Sierra Blanca, and the Red Long of Florence and Red Long of Tropea types, tend toward the sweeter, softer, shorter-keeping end. University of Missouri Extension notes plainly that sweet onions do not store as well as the more pungent types, and that holds true regardless of where you garden.
The long-day varieties, Ailsa Craig, Barolo, Blush, Bridger, New York Early, Patterson, Rossa di Milano, and Walla Walla Sweet, run the gamut, but the pungent ones among them (Patterson and New York Early lean sharper than the others on that list) are the ones that will still be firm when you reach for one in March.
Practically, that means a West Virginia garden can run both lanes at once: plant a bed of intermediate-day onions to eat fresh through late summer, and a bed of the sharper long-day types to cure and stack in a cool basement for winter. Trying to get both qualities out of one variety doesn’t work, because the trade-off is built into the plant’s chemistry, not its care.
Checking this against your own garden
Every figure above comes from Charleston at 38.38°N. If your garden sits well north or south of that, in the Eastern Panhandle, the New River Gorge area, or up along the Ohio River near Wheeling, the day-length math shifts enough to matter for varieties near a published boundary. A few checks take less time than reading a seed catalog:
- Look up your own latitude (a quick search of your town’s coordinates will do) and compare it to the 38.38°N reference point
- If you’re within a degree or two of Charleston, the varieties listed here apply directly; if you’re near the state’s northern or southern edge, lean toward the varieties whose range includes your side of that boundary
- Check your county’s average last and first frost dates, since day length decides bulbing but frost dates decide when you can safely set plants out
- Call your local county extension office, part of the West Virginia University Extension system, and ask what onion varieties local growers report success with
- Note your garden’s actual sun exposure, since a shaded bed delays the leaf growth an onion needs before day length triggers bulbing, even with the right variety