Unlikely — Zone Mismatch
key lime (zones 10-11) does not overlap with North Carolina's zone range (6a-9a). Growing outdoors is unlikely without significant protection.
2 zones short — what would close it
Key Lime is hardy to zone 10, and the warmest ground in North Carolina is zone 8 — 2 zones short. Planted in open ground it will not survive a North Carolina winter. To grow it here, grow key lime under glass — a greenhouse is the only lift this wide the engine models.
A greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 10-11 (plant) against 6-8 (North Carolina). Lift modeled by crop_engine Sprint 20B effective_zone_modifier (+2 zones) via api/fast_sections.py Unlock Engine v2.
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 key lime against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Key Lime Needs
- USDA Zones: 10-11
- Frost-Free Days: 140+
- Sun: Full Sun
- Mature size: 12 ft tall
- Picking window: ~28 days of harvest
- Drought tolerance: Low
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 10-11)
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Key Lime 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 key lime, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether key lime 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: USDA PLANTS Database. 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 key lime does not survive a North Carolina winter in the ground. The season figures below measure a different question — whether it could finish a season here at all — and they only bear on North Carolina under protection.
Frost-free days
Key Lime wants 140+ frost-free days; a typical North Carolina site sees ~245 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Key Lime needs ~4000 GDD (base 50°F) to ripen. The state median runs ~4537 GDD (from PRISM 1991-2020 climate normals), so North Carolina sits right at the threshold — pay attention to siting and microclimate.
Chill hours
Key Lime has no winter-chill requirement — its listed minimum is 0 hours (USDA PLANTS Database). North Carolina typically banks ~1688 chill hours per winter (from PRISM 1991-2020 climate normals), so chill is not a constraint on this plant here — and not evidence in its favour either. Winter survival and season length are what decide it.
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
Key Lime 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, raised beds or amendment with compost solve it.
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. Key Lime has low drought tolerance, so it is the fast-draining end that will cost you — your soil map unit, not the state average, is the real answer.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. North Carolina soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Key Lime in North Carolina — Quick Answer
- Verdict: Unlikely — Zone Mismatch
- Plant Zones: 10-11 (USDA PLANTS Database)
- State Zones: 6a-9a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Mar 11 - Mar 24 to Nov 10 - Nov 25 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Key Lime 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 key lime here specifically
Key Lime needs sharp drainage and sends deep roots hardy to about 53°F; in North Carolina, about 14.7% of soils are poorly-drained (SSURGO), and standing water is what actually kills it.
Build key lime up on a coarse, free-draining mound so its crown never sit in saturated soil. How to handle it →
What to actually do about these — and the constraints that apply to every North Carolina grower, not just key lime — 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 key lime to your county's window, not the statewide date.
Key Lime needs about 140 days of frost-free season to complete its cycle. Even Swain County — North Carolina’s shortest season at 178 frost-free days — clears that by 38 days, so season length isn’t the constraint anywhere in North Carolina. What varies is your own parcel.
Across North Carolina’s 100 counties the frost-free season runs from 178 days in Swain County to 303 days in Dare County — a spread of 125 days, which is why a single statewide planting date misleads. The median North Carolina county sees 245 frost-free days, leaving key lime about 105 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"). Key Lime's 140-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
Key Lime draws honeybees (high value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, key lime 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.
Good to Know Before You Plant Key Lime
Key Lime is listed as toxic to dogs, cats (leaves, stems, peel) at a mild level (ASPCA). 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 key lime, the canonical source is NC State Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Key Lime native to North Carolina?
No — the USDA PLANTS Database lists Key Lime 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 USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Key Lime in North Carolina
When can I plant Key Lime 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 Key Lime, 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 Key Lime grown in across North Carolina?
North Carolina spans USDA hardiness zones 6a-9a (USDA ARS PHZM 2023). Key Lime carries a range of zones 10-11, 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). Key Lime 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 Key Lime native to North Carolina?
No — the USDA PLANTS Database lists Key Lime 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 Key Lime in North Carolina?
Key Lime prefers pH 5.5-8.3 and well (dry spells) drainage (FAO ECOCROP). 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 Key Lime actually grow on my specific land in North Carolina?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores key lime 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 North Carolina
State-level data is a sketch. Your Growable Ground report scores key lime against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that North Carolina key lime 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 key lime average
Explore More
Growing guides for key lime
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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