Unlikely — Zone Mismatch
asystasia (zones 10-13) 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
Asystasia 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 asystasia 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 10-13 (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 has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score asystasia against your land's actual soil, sun, and frost.
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Zone Comparison
Asystasia Needs
- USDA Zones: 10-13
- Frost-Free Days: 42+
- Sun: Part Sun
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 10-13)
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 Asystasia 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.
Frost tenderness
Asystasia is frost-tender — its listed minimum temperature is 46.4°F (USDA PLANTS Database) — so set plants out two to three weeks PAST your local last hard freeze, not on it and not on the state's earliest date. The 28°F marker above is when killing freezes stop, not when light frost does.
When to start the seed
Asystasia is direct-sown where it grows rather than started under cover, so there is no seed-tray head start to bank — North Carolina's dates above are the whole calendar for it. That makes the last-freeze date the binding constraint, and a warmer pocket of your own yard is worth more to this crop than it is to a transplanted one.
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 asystasia 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
Asystasia wants 42+ 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
Asystasia prefers acidic soil (pH 3.5-5). North Carolina's red clay (piedmont) can run on the acidic side, which often aligns well — confirm with a soil test before planting. It will grow across that whole span, but it does best between pH 4 and 4.5 — worth knowing before you decide whether a North Carolina soil test result is a problem or just a number. Drainage matters: this plant wants poorly (saturated >50% of year), 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. Asystasia 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 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.
Asystasia in North Carolina — Quick Answer
- Verdict: Unlikely — Zone Mismatch
- Plant Zones: 10-13 (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 Asystasia 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 asystasia here specifically
Asystasia rates to USDA zones 10–13 and is hardy to about 46°F, but cold isn't the risk in North Carolina — wet is: with roughly 14.7% of its soils poorly-drained (SSURGO), soggy ground rots the roots.
Give asystasia a raised bed or mounded row with coarse amendment so its roots never sit wet. How to handle it →
What to actually do about these — and the constraints that apply to every North Carolina grower, not just asystasia — 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 asystasia to your county's window, not the statewide date.
Asystasia needs about 42 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 136 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 asystasia about 203 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"). Asystasia's 42-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
Asystasia 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, asystasia 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.
North Carolina Cooperative Extension
For North Carolina-specific cultivar recommendations, planting calendars, and pest pressure for asystasia, the canonical source is NC State Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Asystasia native to North Carolina?
No — the USDA PLANTS Database lists Asystasia 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 Asystasia in North Carolina
When can I plant Asystasia 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). Asystasia is frost-tender — its listed minimum temperature is 46.4°F (USDA PLANTS Database) — so wait two to three weeks past your site's last hard freeze, when light frost has also stopped, before planting out.
What hardiness zone is Asystasia grown in across North Carolina?
North Carolina spans USDA hardiness zones 6a-9a (USDA ARS PHZM 2023). Asystasia carries a range of zones 10-13, 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). Asystasia needs 42+ 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 Asystasia native to North Carolina?
No — the USDA PLANTS Database lists Asystasia 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 Asystasia in North Carolina?
Asystasia prefers pH 3.5-5 and poorly (saturated >50% of year), well (dry spells) drainage (FAO ECOCROP). Most North Carolina soils run mildly acidic to neutral; many sites land near this band naturally, and a soil test plus targeted sulfur or organic amendment closes any gap.
Will Asystasia actually grow on my specific land in North Carolina?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores asystasia 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 asystasia against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that North Carolina asystasia 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 asystasia average
Explore More
Growing guides for asystasia
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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