Conditional — Some Areas
sour orange (zones 9-11) reaches only part of North Carolina (6a-9a): zone 9 are in range, so where you are in the state decides it.
One zone short — what would close it
Sour Orange is hardy to zone 9, and the warmest ground in North Carolina is zone 8 — 1 zone short. Planted in open ground it will not survive a North Carolina winter. To grow it here, grow sour orange in a hoop house or unheated greenhouse — its modeled 1.5-zone lift covers this gap.
A hoop house or unheated greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 9-11 (plant) against 6-8 (North Carolina). Lift modeled by crop_engine.GREENHOUSE_ZONE_MODIFIER_BY_SUBTYPE['hoop_house'] (+1.5 zones) via api/fast_sections.py Unlock Engine v2.
Sour Orange in North Carolina — the short answer
Sour Orange in North Carolina: hardy in zones 9–11, full sun.
- Plant zones
- 9-11
- Not verified — NC State Extension Gardener Plant Toolbox lists zones 8a–11b
- North Carolina zones
- 6a-9a
- USDA PHZM 2023
- Frost window
- Mar 11 - Mar 24 – Nov 10 - Nov 25
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 178 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
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.
North Carolina spans zones 6a-9a, 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 sour orange 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.
No card required · your parcel report in seconds — read in full free for your first 14 days
North Carolina is not one climate
North Carolina’s winter-low ladder runs across 100 counties, from zone 6.5 in Avery County to zone 9 in Dare County. That is 25°F between the two counties’ average coldest night — the difference between sour orange overwintering in the ground and coming under cover.
The middle half of 100 counties runs 7.5–8 zones, with a median of 8 zones — a 2.5-zone span end to end.
Measured across 100 North Carolina 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 North Carolina Fits Best
Sour Orange is rated for zones 9–11 — a cold floor USDA puts at 20 to 30°F. Against North Carolina’s 100 counties that band holds in 1 of them, and the line runs at Dare County (zone 9a), the coldest county still inside it.
Inside zones 9–11
1 county
0 of 1 shown
Below the zone 9 floor
99 counties
- Avery County · zone 6b
- Swain County · zone 6b
- Watauga County · zone 6b
3 of 99 shown
Winter cold is the limit here — the same plant works in a container that comes under cover.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. A zone is a 10°F band of average annual extreme minimum temperature, so the floor above is the band the plant's rating denotes, not a single measured kill point. Slope, shelter and cold-air drainage routinely move a site half a zone either way from its county figure — which is the part only your address resolves.
Even within North Carolina's zones 6a-9a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for sour orange (USDA PHZM 2023):
Zone Comparison
Sour Orange Needs
- USDA Zones: 9-11
- Sun: Full SunWe haven't confirmed this against a published source yet.
- Picking window: ~28 days of harvestWe haven't confirmed this against a published source yet.
North Carolina Has
- USDA Zones: 6a-9a
- Last Hard Freeze (28°F): Mar 11 - Mar 24
- First Hard Freeze (28°F): Nov 10 - Nov 25
- Annual Rainfall: 40-60 inches
- Common Soils: Red clay (Piedmont), Sandy loam (Coastal), Mountain loam
Plant Zone Range (zones 9-11)
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 Sour Orange in North Carolina
The frost window
Across North Carolina, the last spring hard freeze (28°F) clears between Mar 11 and Mar 24, and the first fall hard freeze lands between Nov 10 and Nov 25 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 231-day window you can count on — up to 259 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.
Winter standing
North Carolina runs as cold as USDA zone 6, and no sourced winter-hardiness floor is on record for sour orange, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether sour orange is a permanent planting or a replant-every-spring crop for you turns on your own zone within North Carolina; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Swain 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.
Soil + Drainage Fit
Sour Orange likes near-neutral soil (pH 5.5-8.3). That's the common-ground band across North Carolina's red clay (piedmont) and sandy loam (coastal) — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6 and 7 — worth knowing before you decide whether a North Carolina soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your North Carolina site is heavier clay or sits in a low spot, a raised bed lifts the roots above wet ground, or work in compost. Drainage need: We haven't confirmed this against a published source yet.
Your land, not the state average
SSURGO maps about 14.7% of North Carolina as poorly or somewhat-poorly drained, and the class flips parcel to parcel. Sour Orange sits mid-range for drought tolerance, so either extreme can cost you — your soil map unit, not the state average, is the real answer.
Check your parcel → Source: USDA NRCS SSURGO.
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. North Carolina soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Before you plant sour orange 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 sour orange goes in. What follows is North Carolina’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 North Carolina — and how to grow with it.
We checked the federal record across North Carolina — 33,708 documented sites across 7 of the 8 source types we track.
The most significant on record: 464 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
North Carolina 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 of imported, lab-tested soil grow well almost anywhere in the meantime.
Sources Checked
across North Carolina
Severity Distribution
across North Carolina
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •TRI facilities report what they release. Check the wind — downwind beds catch more of it.
- •Near a brownfield, a raised bed of imported, lab-tested soil lowers contact with the ground; it does not remove it.
Sources: EPA, USGS — 950K documented sites tracked nationwide across 8 federal source types.
What Else to Consider for Sour Orange in North Carolina
Zone compatibility tells you about winter cold survival — but North Carolina growers also need to think about:
Red Piedmont clay is hard to work and drains poorly
Humidity drives significant disease pressure
Hurricane risk on the coastal plain
Growing sour orange here specifically
Sour Orange roots run deep and prefer pH 5.5–8.3, but drainage comes first here: SSURGO maps about 14.7% of North Carolina as poorly or somewhat-poorly drained, and wet ground rots its crown before pH ever matters.
Plant sour orange on a raised, gravel-amended berm so water drains fast and the crown stays dry. How to handle it →
What to actually do about these — and the constraints that apply to every North Carolina grower, not just sour orange — is covered on the North Carolina growing guide.
Timing shifts within North Carolina
North Carolina isn't one climate. In Swain County, the last hard freeze (28°F) holds until about Apr 27 — roughly 41 days later than the recorded state median — so plant sour orange to your county's window, not the statewide date.
County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). A parcel report resolves your address's own frost dates.
Where in North Carolina Sour Orange Is Zone-Hardy
Sour Orange is rated for USDA zones 9–11. 1 of North Carolina’s 100 counties fall inside that band. The coldest that does is Dare County at zone 9a. 99 counties sit below the plant’s zone 9 floor, where an unprotected plant is relying on snow cover and a mild year. Where you are in North Carolina decides this one.
Across those 100 counties North Carolina’s winter-low ladder runs from zone 6b in Avery County to zone 9a in Dare County — 2.5 USDA zones of spread, which is 25°F between the two counties’ average coldest night of the year. That is why a statewide hardiness answer is where you start and not where you finish.
The planting window moves with it. Swain County holds its last hard freeze (28°F) until about Apr 27, while Dare County is clear by Feb 18 — 68 days apart. Set sour orange out on your county’s date, not the state’s.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F killing freeze — earlier than the folk 32°F "last frost". Sour Orange’s zone 9–11 band: Not verified — NC State Extension Gardener Plant Toolbox lists zones 8a–11b. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Sour Orange draws honeybees (high value). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, sour orange can only work that bloom inside North Carolina's frost window — roughly 245 days, opening after the last 28°F freeze (Mar 11 - Mar 24) and closing at the first (Nov 10 - Nov 25), per NOAA Regional Climate Centers ACIS, 1991-2020. Pollinator value: We haven't confirmed this against a published source yet.
Good to Know Before You Plant Sour Orange
Sour Orange is listed as toxic to dogs, cats (leaves, stems, peel) at a mild level. We haven't confirmed this against a published source yet. Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear.
North Carolina Cooperative Extension
For North Carolina-specific cultivar recommendations, planting calendars, and pest pressure for sour orange, the canonical source is NC State Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Sour Orange native to North Carolina?
No — the USDA PLANTS Database lists Sour Orange as introduced rather than native in the Lower 48, so it is not part of North Carolina's native flora. It grows here as a garden plant; pairing it with a few North Carolina natives keeps local pollinators fed too.
Looking for plants that belong here? The North Carolina growing guide lists plants that USDA PLANTS records growing in North Carolina and that Kew and NatureServe Explorer both list in its native range, leaving out any that NatureServe flags as exotic there or that our audit holds.
State records: USDA PLANTS Database state-distribution data (presence, not state-level nativity), accessed 2026-10-19.
Common Questions About Growing Sour Orange in North Carolina
When can I plant Sour Orange in North Carolina?
North Carolina's last spring hard freeze (28°F) clears between Mar 11 and Mar 24, and the first fall hard freeze lands between Nov 10 and Nov 25 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Sour Orange, so this page does not state whether it overwinters in North Carolina and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Sour Orange grown in across North Carolina?
North Carolina spans USDA hardiness zones 6a-9a (USDA ARS PHZM 2023). Sour Orange carries a range of zones 9-11, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical North Carolina site have?
A typical North Carolina site sees ~245 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Sour Orange needs 140+ 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 Swain, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Sour Orange native to North Carolina?
No — the USDA PLANTS Database lists Sour Orange as introduced rather than native in the Lower 48, so it is not part of North Carolina's native flora. It grows here as a garden plant; pairing it with a few North Carolina natives keeps local pollinators fed too.
How should I amend the soil for Sour Orange in North Carolina?
Sour Orange prefers pH 5.5-8.3 and well (dry spells) drainage. We haven't confirmed this against a published source yet. That sits in the common-ground band across North Carolina soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Sour Orange actually grow on my specific land in North Carolina?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores sour orange against your address's mapped soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in North Carolina
State-level data is a sketch. Your Growable Ground report scores sour orange against your land's mapped soil, modelled sun, drainage, and frost data — not zone averages.
Three things about your lot that North Carolina sour orange averages can't show:
We read public map data around North Carolina — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the North Carolina sour orange average
Explore More
Growing guides for sour orange
Explore North Carolina county by county
North Carolina carries 100 counties with their own USDA zone — a sample of the growing pages for sour orange there:
Where else sour orange grows
Sour Orange's zone band crosses state lines — these are the states closest to North Carolina 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 North Carolina
North Carolina has a growing page for 1,011 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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