Conditional — Some Areas
ashwagandha (zones 8-12) reaches only part of Oklahoma (6b-8b): zone 8 are in range, so where you are in the state decides it.
Ashwagandha in Oklahoma — the short answer
Ashwagandha in Oklahoma: hardy in zones 8–12, full sun, against a state median of ~237 frost-free days.
- Plant zones
- 8-12
- 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
- Oklahoma zones
- 6b-8b
- USDA PHZM 2023
- Frost window
- Mar 15 - Mar 26 – Nov 9 - Nov 14
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 197 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 150 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.
Oklahoma spans zones 6b-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 ashwagandha 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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Oklahoma is not one climate
Oklahoma’s winter-low ladder runs across 77 counties, from zone 6.5 in Beaver County to zone 8 in Tillman County. That is 15°F between the two counties’ average coldest night — the difference between ashwagandha overwintering in the ground and coming under cover.
The middle half of 77 counties runs 7–7.5 zones, with a median of 7.5 zones — a 1.5-zone span end to end.
Measured across 77 Oklahoma 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 Oklahoma Fits Best
Ashwagandha is rated for zones 8–12 — a cold floor USDA puts at 10 to 20°F. Against Oklahoma’s 77 counties that band holds in 14 of them, and the line runs at Atoka County (zone 8a), the coldest county still inside it.
Inside zones 8–12
14 counties
- Bryan County · zone 8a
- Carter County · zone 8a
- Choctaw County · zone 8a
3 of 14 shown
Below the zone 8 floor
63 counties
- Beaver County · zone 6b
- Cimarron County · zone 6b
- Texas County · zone 6b
3 of 63 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 Oklahoma's zones 6b-8b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for ashwagandha (USDA PHZM 2023):
Zone Comparison
Ashwagandha Needs
- USDA Zones: 8-12
- Frost-Free Days: 150+
- Sun: Full Sun
- Mature size: 3 ft tall
- Drought tolerance: High
Oklahoma Has
- USDA Zones: 6b-8b
- Last Hard Freeze (28°F): Mar 15 - Mar 26
- First Hard Freeze (28°F): Nov 9 - Nov 14
- Annual Rainfall: 15-56 inches
- Common Soils: Red clay, Sandy loam, Prairie loam
Plant Zone Range (zones 8-12)
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 Ashwagandha in Oklahoma
The frost window
Across Oklahoma, the last spring hard freeze (28°F) clears between Mar 15 and Mar 26, and the first fall hard freeze lands between Nov 9 and Nov 14 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 228-day window you can count on — up to 244 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 ashwagandha goes out, not when it starts. It is sown under cover about 8 weeks ahead, so counting back from Oklahoma's late-side last freeze of Mar 26 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Winter standing
Oklahoma runs as cold as USDA zone 6, and no sourced winter-hardiness floor is on record for ashwagandha, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether ashwagandha is a permanent planting or a replant-every-spring crop for you turns on your own zone within Oklahoma; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Cimarron 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 ashwagandha survives winter in part of Oklahoma, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Ashwagandha wants 150+ frost-free days; a typical Oklahoma site sees ~237 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Ashwagandha needs ~2000 GDD (base 50°F) to ripen. The state median runs ~4695 GDD (from PRISM 1991-2020 climate normals), so Oklahoma'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
Ashwagandha likes near-neutral soil (pH 6.5-8.5). That's the common-ground band across Oklahoma's red clay and sandy loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 7.5 and 8 — worth knowing before you decide whether a Oklahoma soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Oklahoma site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Oklahoma's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Ashwagandha needs about 19 inches of workable depth, so it is that horizon — not the surface — you are testing for. That map unit, not the state average, decides how ashwagandha performs.
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. Oklahoma soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Before you plant ashwagandha 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 ashwagandha goes in. What follows is Oklahoma’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 Oklahoma — and how to grow with it.
We checked the federal record across Oklahoma — 24,720 documented sites across 8 of the 9 source types we track.
The most significant on record: 151 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Oklahoma 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 Oklahoma
Severity Distribution
across Oklahoma
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What Else to Consider for Ashwagandha in Oklahoma
Zone compatibility tells you about winter cold survival — but Oklahoma growers also need to think about:
Extreme weather variability (tornadoes, ice storms, drought)
Red clay soils drain poorly in central OK
Low western rainfall requires irrigation
Growing ashwagandha here specifically
Ashwagandha prefers pH 6.5–8.5 and room to root medium; across much of Oklahoma, restrictive group-D subsoil (SSURGO) blocks that depth.
Build ashwagandha a deep raised bed of loose soil to bypass the dense subsoil entirely. How to handle it →
What to actually do about these — and the constraints that apply to every Oklahoma grower, not just ashwagandha — is covered on the Oklahoma growing guide.
Timing shifts within Oklahoma
Oklahoma isn't one climate. In Cimarron County, the last hard freeze (28°F) holds until about Apr 13 — roughly 24 days later than the recorded state median — so plant ashwagandha to your county's window, not the statewide date.
Ashwagandha needs about 150 days of frost-free season to complete its cycle. Even Cimarron County — Oklahoma’s shortest season at 197 frost-free days — clears that by 47 days, so season length isn’t the constraint anywhere in Oklahoma. What varies is your own parcel.
Across Oklahoma’s 77 counties the frost-free season runs from 197 days in Cimarron County to 267 days in Choctaw County — a spread of 70 days, which is why a single statewide planting date misleads. The median Oklahoma county sees 237 frost-free days, leaving ashwagandha about 87 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"). Ashwagandha's 150-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
Ashwagandha draws honeybees (low value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, ashwagandha can only work that bloom inside Oklahoma's frost window — roughly 237 days, opening after the last 28°F freeze (Mar 15 - Mar 26) and closing at the first (Nov 9 - Nov 14), per NOAA Regional Climate Centers ACIS, 1991-2020.
Good to Know Before You Plant Ashwagandha
Ashwagandha is listed as toxic to dogs, cats (all) at a mild level (Pet Poison Helpline). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear.
Recommended Ashwagandha Varieties for Oklahoma
Oklahoma publishes no state variety trial for ashwagandha, so we won't invent a "best for Oklahoma" list. Choose types rated to your USDA hardiness zone (6b-8b), and confirm winter survival and drainage against your own parcel.
Oklahoma Cooperative Extension
For Oklahoma-specific cultivar recommendations, planting calendars, and pest pressure for ashwagandha, the canonical source is Oklahoma State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Ashwagandha in Oklahoma
When can I plant Ashwagandha in Oklahoma?
Oklahoma's last spring hard freeze (28°F) clears between Mar 15 and Mar 26, and the first fall hard freeze lands between Nov 9 and Nov 14 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Ashwagandha, so this page does not state whether it overwinters in Oklahoma 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 Ashwagandha grown in across Oklahoma?
Oklahoma spans USDA hardiness zones 6b-8b (USDA ARS PHZM 2023). Ashwagandha carries a range of zones 8-12, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Oklahoma site have?
A typical Oklahoma site sees ~237 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Ashwagandha needs 150+ 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 Cimarron, the freeze-free season runs shorter than the state average, so verify your own county's window.
How should I amend the soil for Ashwagandha in Oklahoma?
Ashwagandha prefers pH 6.5-8.5 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Oklahoma soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Ashwagandha actually grow on my specific land in Oklahoma?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores ashwagandha 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 Oklahoma
State-level data is a sketch. Your Growable Ground report scores ashwagandha against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Oklahoma ashwagandha averages can't show:
We read public map data around Oklahoma — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Oklahoma ashwagandha average
Explore More
Growing guides for ashwagandha
Explore Oklahoma county by county
Oklahoma carries 77 counties with their own USDA zone — a sample of the growing pages for ashwagandha there:
Where else ashwagandha grows
Ashwagandha's zone band crosses state lines — these are the states closest to Oklahoma 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 Oklahoma
Oklahoma 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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