Conditional — Some Areas
potato yam (zones 9-12) 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
Potato Yam 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 potato yam 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 9-12 (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.
Potato Yam in North Carolina — the short answer
Potato Yam in North Carolina: hardy in zones 9–12, full sun, against a state median of ~245 frost-free days.
- Plant zones
- 9-12
- 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
- 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 potato yam 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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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 potato yam 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
Potato Yam is rated for zones 9–12 — 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 9–12
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 potato yam (USDA PHZM 2023):
Zone Comparison
Potato Yam Needs
- USDA Zones: 9-12
- Frost-Free Days: 90+
- Sun: Full Sun
- Picking window: ~30 days of harvest
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 9-12)
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 Potato Yam 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 potato yam, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether potato yam 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.
Growing Season Fit
The zone check says potato yam survives winter in part of North Carolina, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Potato Yam wants 90+ frost-free days; a typical North Carolina site sees ~245 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
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
Potato Yam likes near-neutral soil (pH 5.3-8). 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 6.7 — 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. Potato Yam 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 potato yam 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 potato yam 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 — 45,236 documented sites across 8 of the 9 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 with clean imported soil grow well almost anywhere in the meantime.
Sources Checked
across North Carolina
Severity Distribution
across North Carolina
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around North Carolina, Underground Storage Tanks runs higher than the national average — 28,735 sites across North Carolina. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Potato Yam 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 potato yam here specifically
Potato Yam roots run deep and prefer pH 5.3–8.0, 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 potato yam 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 potato yam — 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 potato yam to your county's window, not the statewide date.
Potato Yam needs about 90 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 88 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 potato yam about 155 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"). Potato Yam's 90-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
Potato Yam draws native bees (low value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, potato yam 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 Potato Yam
Potato Yam is listed as toxic to dogs, cats (all) at a moderate level (Cornell). 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 potato yam, the canonical source is NC State Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Potato Yam native to North Carolina?
No — the USDA PLANTS Database lists Potato Yam 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 Potato Yam in North Carolina
When can I plant Potato Yam 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 Potato Yam, 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 Potato Yam grown in across North Carolina?
North Carolina spans USDA hardiness zones 6a-9a (USDA ARS PHZM 2023). Potato Yam carries a range of zones 9-12, 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). Potato Yam needs 90+ 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 Potato Yam native to North Carolina?
No — the USDA PLANTS Database lists Potato Yam 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 Potato Yam in North Carolina?
Potato Yam prefers pH 5.3-8 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 Potato Yam actually grow on my specific land in North Carolina?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores potato yam 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 potato yam against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that North Carolina potato yam 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 potato yam average
Explore More
Growing guides for potato yam
Explore North Carolina county by county
North Carolina carries 100 counties with their own USDA zone — a sample of the growing pages for potato yam there:
Where else potato yam grows
Potato Yam'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 1,020 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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