Yes — Strong Match
onion (zones 2-11) covers every zone Virginia contains (5b-8b), so hardiness is not what limits it anywhere in the state.
Onion in Virginia — the short answer
Onion in Virginia: hardy in zones 2–11, full sun, against a state median of ~224 frost-free days.
- Plant zones
- 2-11
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Virginia zones
- 5b-8b
- USDA PHZM 2023
- Frost window
- Mar 22 - Apr 2 – Nov 2 - Nov 17
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 176 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 110 days
- Growable Ground Plant Database
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Virginia spans zones 5b-8b, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score onion against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Virginia is not one climate
Virginia’s winter-low ladder runs across 133 counties, from zone 6 in Highland County to zone 8.5 in York County. That is 25°F between the two counties’ average coldest night — the difference between onion overwintering in the ground and coming under cover.
The middle half of 133 counties runs 7–7.5 zones, with a median of 7.5 zones — a 2.5-zone span end to end.
Measured across 133 Virginia counties. USDA PHZM 2023, per county. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where in Virginia Fits Best
Even within Virginia's zones 5b-8b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for onion (USDA PHZM 2023):
Zone Comparison
Onion Needs
- USDA Zones: 2-11
- Frost-Free Days: 85+
- Sun: Full Sun
- Mature size: 1.5 ft tall
- Picking window: ~7 days of harvest
- Drought tolerance: Medium
Virginia Has
- USDA Zones: 5b-8b
- Last Hard Freeze (28°F): Mar 22 - Apr 2
- First Hard Freeze (28°F): Nov 2 - Nov 17
- Annual Rainfall: 36-50 inches
- Common Soils: Red clay (Piedmont), Silt loam, Sandy loam (Tidewater)
Plant Zone Range (zones 2-11)
Preferred Soil pH
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Onion in Virginia
The frost window
Across Virginia, the last spring hard freeze (28°F) clears between Mar 22 and Apr 2, and the first fall hard freeze lands between Nov 2 and Nov 17 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 214-day window you can count on — up to 240 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
When to start the seed
Those dates are when onion goes out, not when it starts. It is sown under cover about 9 weeks ahead, so counting back from Virginia's late-side last freeze of Apr 2 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Establishment timing
As a long-lived plant, onion isn't racing the calendar to a harvest date. Plant it in spring once the last hard-freeze window passes so roots settle in through the full season, or in early fall while the soil still holds summer warmth.
Timing tuned to sub-state frost dates — Highland County, not the statewide average.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
The zone check says onion survives winter here. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Onion wants 85+ frost-free days; a typical Virginia site sees ~224 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Onion needs ~1700 GDD (base 50°F) to ripen. The state median runs ~3662 GDD (from PRISM 1991-2020 climate normals), so Virginia's typical season clears that easily.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
Onion tolerates a wide pH range (pH 4.3-8.3) — 4 units, acid ground through alkaline — so soil acidity is rarely what limits it in Virginia. A soil test is still worth having, but for what else it tells you about this site, not to clear this plant. It will grow across that whole span, but it does best between pH 6 and 7 — worth knowing before you decide whether a Virginia soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Virginia site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Whether onion is safe to eat from Virginia soil is a block-by-block question, not a town-wide one — 37,636 documented contamination sites mean levels spike on some parcels and not the one next door. Onion roots to about 19 inches, so it is the top 19 inches under your address that decide what it takes up, so only a test on your address settles it.
Check your parcel → Source: USDA NRCS SSURGO + EPA/state contamination databases.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Virginia soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Before you plant onion for food
Anything you grow to eat takes up what is in the ground it grows in, so what is on record near you is worth knowing before onion goes in. What follows is Virginia’s documented federal record at state scale — a screening signal, not a soil test, and not a statement about any one lot.
Safe to Grow Here?
What the federal record shows across Virginia — and how to grow with it.
We checked the federal record across Virginia — 37,636 documented sites across 8 of the 9 source types we track.
The most significant on record: 164 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Virginia carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources Checked
across Virginia
Severity Distribution
across Virginia
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Virginia, Underground Storage Tanks runs higher than the national average — 24,515 sites across Virginia. That's not a problem with your land — it's information about it.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What Else to Consider for Onion in Virginia
Zone compatibility tells you about winter cold survival — but Virginia growers also need to think about:
Heavy Piedmont red clay requires amendment
Humidity and heat in summer promote disease
Deer pressure is heavy in suburban and rural areas
Growing onion here specifically
Onion is a bulb crop whose edible part grows in or against the soil and can take up lead, and Virginia carries 37,636 documented contamination sites where legacy fill and old paint push metals up parcel by parcel.
Grow onion in raised beds of tested clean soil and run a parcel soil-lead test before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Virginia grower, not just onion — is covered on the Virginia growing guide.
Timing shifts within Virginia
Virginia isn't one climate. In Highland County, the last hard freeze (28°F) holds until about Apr 27 — roughly 30 days later than the recorded state median — so plant onion to your county's window, not the statewide date.
Onion needs about 85 days of frost-free season to complete its cycle. Even Highland County — Virginia’s shortest season at 176 frost-free days — clears that by 91 days, so season length isn’t the constraint anywhere in Virginia. What varies is your own parcel.
Across Virginia’s 133 counties the frost-free season runs from 176 days in Highland County to 289 days in Hampton County — a spread of 113 days, which is why a single statewide planting date misleads. The median Virginia county sees 224 frost-free days, leaving onion about 139 days of slack on a typical parcel — room for a second sowing where the season runs long.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Onion's 85-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Onion draws honeybees, native bees, and butterflies (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, onion can only work that bloom inside Virginia's frost window — roughly 224 days, opening after the last 28°F freeze (Mar 22 - Apr 2) and closing at the first (Nov 2 - Nov 17), per NOAA Regional Climate Centers ACIS, 1991-2020.
Good to Know Before You Plant Onion
Onion is listed as toxic to dogs, cats (all) at a moderate level (ASPCA). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear. Worth knowing for placement: onion overwinters through Virginia — its sourced hardiness floor is zone 5 and the state runs no colder than zone 5 — so it stands in the bed year-round, and where you site it is a long-term decision.
Virginia Cooperative Extension
For Virginia-specific cultivar recommendations, planting calendars, and pest pressure for onion, the canonical source is Virginia Cooperative Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Onion native to Virginia?
No — the USDA PLANTS Database lists Onion as introduced rather than native in the Lower 48, so it is not part of Virginia's native flora. It grows here as a garden plant; pairing it with a few Virginia natives keeps local pollinators fed too.
Looking for plants that belong here? The Virginia growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Onion in Virginia
When can I plant Onion in Virginia?
Virginia's last spring hard freeze (28°F) clears between Mar 22 and Apr 2, and the first fall hard freeze lands between Nov 2 and Nov 17 (NOAA Regional Climate Centers ACIS, 1991-2020). Onion is a long-lived planting, so target spring just after your local last hard freeze — or early fall while the soil holds warmth — and let it establish through the season.
What hardiness zone is Onion grown in across Virginia?
Virginia spans USDA hardiness zones 5b-8b (USDA ARS PHZM 2023). Onion carries a range of zones 2-11, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Virginia site have?
A typical Virginia site sees ~224 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Onion needs 85+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Highland, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Onion native to Virginia?
No — the USDA PLANTS Database lists Onion as introduced rather than native in the Lower 48, so it is not part of Virginia's native flora. It grows here as a garden plant; pairing it with a few Virginia natives keeps local pollinators fed too.
How should I amend the soil for Onion in Virginia?
Onion tolerates pH 4.3-8.3 and well (dry spells) drainage (FAO ECOCROP). That is a 4-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Virginia site — amend for drainage and organic matter first.
Will Onion actually grow on my specific land in Virginia?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores onion against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Virginia
State-level data is a sketch. Your Growable Ground report scores onion against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Virginia onion averages can't show:
We read public map data around Virginia — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Virginia onion average
Explore More
Growing guides for onion
Explore Virginia county by county
Virginia carries 133 counties with their own USDA zone — a sample of the growing pages for onion there:
Where else onion grows
Onion's zone band crosses state lines — these are the states closest to Virginia in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Virginia
Virginia has a growing page for 1,020 plants — a rotating sample of the rest of the shelf.
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
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