Yes — Strong Match
good king henry is grown as an annual, so season length decides it here, not a winter zone — and Oklahoma's typical season runs ~237 frost-free days against the ~60 good king henry needs.
Sow by about Sep 13
Good King Henry is grown as an annual, so what decides it here is season length, not a winter zone. It needs about 60 days from sowing to finish and a typical Oklahoma season runs ~237 frost-free days, leaving 177 days of slack. That is room to sow as late as about Sep 13 and still finish before the usual first freeze (Nov 12), or to run a second succession.
Want more weeks at either end of that window? How to buy the weeks →
60 days to maturity against Oklahoma’s ~237-day season. NOAA Regional Climate Centers ACIS 1991-2020 (28°F killing freeze), state median across counties, via stateClimateData.ts.
Your yard isn't the whole zone.
Good King Henry is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Oklahoma site runs ~237 frost-free days, but that is a state median, not your yard: slope, trees, and low spots move the last-frost date across a single parcel. Enter your address and we'll score good king henry against your land's actual frost dates, sun, and soil.
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Zone Comparison
Good King Henry Needs
- USDA Zones: Data pending
- Sun: Full Sun
- Mature size: 1 ft tall
- Picking window: ~90 days of harvest
- Drought tolerance: Medium
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
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 Good King Henry 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 good king henry goes out, not when it starts. It is sown under cover about 4 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.
Days to maturity vs. the window
At 60 days to maturity (USDA PLANTS Database), counting from the last hard freeze it ripens with 168 days to spare even in Oklahoma's tightest freeze scenario — room for a later start or a second sowing.
Timing tuned to sub-state frost dates — Cimarron 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
Days to maturity
Good King Henry matures in ~60 days (Growable Ground Plant Database). A typical Oklahoma site has ~237 frost-free days, so plenty of room for a second succession.
Growing degree days
Good King Henry needs ~700 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
Good King Henry likes near-neutral soil (pH 5.5-8). 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 6 and 7.5 — 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. What matters for good king henry is the horizon its roots actually work, not the surface. That map unit, not the state average, decides how good king henry performs.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. Oklahoma soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Good King Henry in Oklahoma — Quick Answer
- Verdict: Yes — Strong Match
- Plant Zones: Data pending (USDA PLANTS Database)
- State Zones: 6b-8b (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Mar 15 - Mar 26 to Nov 9 - Nov 14 (NOAA Regional Climate Centers ACIS, 1991-2020)
- Days to Maturity: 60 days
What Else to Consider for Good King Henry 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 good king henry here specifically
Oklahoma's soils run mostly silt loam (Mollisols), and whether that suits good king henry's pH 5.5–8.0 preference comes down to your exact parcel, not the statewide picture.
Pull your parcel's SSURGO map unit, test pH, and amend toward good king henry's 5.5–8.0 target before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Oklahoma grower, not just good king henry — 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 good king henry to your county's window, not the statewide date.
Good King Henry needs about 60 days of frost-free season from planting to harvest. Even Cimarron County — Oklahoma’s shortest season at 197 frost-free days — clears that by 137 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 good king henry about 177 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"). Good King Henry's 60-day requirement: USDA PLANTS / Growable Ground plant database (days to maturity). A parcel report resolves your address's own frost dates.
Good to Know Before You Plant Good King Henry
Good King Henry is listed as toxic to dogs, cats (leaves) at a mild level (Cornell). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear. Worth knowing for placement: in Oklahoma this is a one-season plant and the first hard freeze (Nov 9 - Nov 14) takes it down, so the exposure above is a summer-long one rather than something standing in the bed all year.
Recommended Good King Henry Varieties for Oklahoma
Oklahoma publishes no state variety trial for good king henry, 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 good king henry, the canonical source is Oklahoma State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Good King Henry native to Oklahoma?
No — the USDA PLANTS Database lists Good King Henry as introduced rather than native in the Lower 48, so it is not part of Oklahoma's native flora. It grows here as a garden plant; pairing it with a few Oklahoma natives keeps local pollinators fed too.
Looking for plants that belong here? The Oklahoma 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 Good King Henry in Oklahoma
When can I plant Good King Henry 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). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
Can Good King Henry mature before first frost in Oklahoma?
Yes — Good King Henry matures in 60 days (USDA PLANTS Database), and Oklahoma's dependable hard-freeze-free window runs 228 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 168 days of margin. Plant once the last hard freeze has passed — two to three weeks later for anything tender — and it ripens ahead of the first fall freeze.
What hardiness zone is Good King Henry grown in across Oklahoma?
Oklahoma spans USDA hardiness zones 6b-8b (USDA ARS PHZM 2023). Good King Henry carries a range of zones Data pending, 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). Good King Henry should be matched against that window, 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.
Is Good King Henry native to Oklahoma?
No — the USDA PLANTS Database lists Good King Henry as introduced rather than native in the Lower 48, so it is not part of Oklahoma's native flora. It grows here as a garden plant; pairing it with a few Oklahoma natives keeps local pollinators fed too.
How should I amend the soil for Good King Henry in Oklahoma?
Good King Henry prefers pH 5.5-8 and well (dry spells) drainage (Growable Ground Plant Database). 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 Good King Henry actually grow on my specific land in Oklahoma?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores good king henry 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 good king henry against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Oklahoma good king henry 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 good king henry average
Explore More
Growing guides for good king henry
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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