Blackburn, Oklahoma, sits in USDA hardiness zone 7a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Expect cabbage, hazelnut, california poppy, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Blackburn, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Blackburn lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Blackburn — soil, climate, flood, and parcel records. How we handle your address.
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Blackburn — the short answer
Blackburn, Oklahoma: USDA zone 7a, about 233 days between hard freezes, across 189 acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 21
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 9
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~233
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 189 acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 7a is Blackburn's average, not your lot's — a low corner or a tree line moves it. Against Blackburn's 233-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Blackburn
Each reading below is measured for Blackburn itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredBlackburn runs about 233 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredBlackburn sits in USDA hardiness zone 7a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Blackburn is in
Blackburn sits in the Central Great Plains — EPA Level III, inside the wider Great Plains. That is read at Blackburn's own centroid rather than borrowed from Pawnee County.
What Grows in Blackburn
Every plant below cleared Blackburn's own zone 7a and its 233-day season. Each card opens that plant's Oklahoma profile. How we score.
Is it too late to plant in Blackburn?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Feb 21; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 21 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 9 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
What's on the federal record near Blackburn
Closest first, within ~10 miles of Blackburn. Listing isn't leaking, and distance isn't exposure.
- 22N-07E-16 BBD 1Nitrate · 2.3 mi
- Well Owner Name: LorisNitrate · 5.7 mi
- 22N-06E-18 CAA 1Nitrate · 6.0 mi
- Paint And Sandblasting FacilityUnderground Storage Tanks · 6.4 mi
- 21N-07E-11 CAA 1Nitrate · 6.4 mi
- SHAW WORD IND FABRICATORS INC / CLEVELAND PAINT FACILITYToxics Release Inventory · 6.6 mi
- 22N-05E-13 ADC 1Nitrate · 6.6 mi
- Lela North-2Mining · 6.7 mi
- Skedee-1Mining · 6.7 mi
- 23N-07E-09 BDA 1Nitrate · 7.2 mi
- MAGELLAN AMMONIA RELEASESuperfund · 7.5 mi
- Robert Tyler FarmUnderground Storage Tanks · 7.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Blackburn's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Blackburn.
Total Sites
38
within ~10 miles of Blackburn
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Blackburn
Severity Distribution
within ~10 miles of Blackburn
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Blackburn, Nitrate runs higher than the national average — 14 sites within ~10 miles of Blackburn. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Blackburn
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Blackburn average
Your land is one point inside Blackburn
Everything above resolves to Blackburn as a whole — one PHZM band and one 28°F frost record, read across 189 acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at town scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the Blackburn Average
Blackburn Average
- ●USDA Zones 7a, averaged across Blackburn
- ●One soil character for all of Blackburn
- ●Frost dates read at Blackburn's scale: Mar 21 to Nov 9
YOUR Parcel
- ✓Your exact zone, not Blackburn's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Blackburn
Pull a site-specific report for your exact address in Blackburn, Oklahoma — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Blackburn averages can't show:
We read public map data around Blackburn — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Blackburn average
How we know this about Blackburn
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Blackburn’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Blackburn
When does frost risk typically end in Blackburn?
The last hard freeze (28°F) in Blackburn typically lands around Mar 21, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Apr 11.
When is the first frost in Blackburn?
The first hard freeze (28°F) in Blackburn typically arrives around Nov 9, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 26, so the watching starts about Oct 10 — about 233 days after the spring freeze cleared.
How long is the growing season in Blackburn?
Measured between 28°F hard freezes, Blackburn sees about 233 frost-free days — roughly Mar 21 through Nov 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 11 to Oct 26, about 198 days.
Is the soil safe to grow vegetables in Blackburn?
The federal record around Blackburn is a meaningful one — 38 documented sites, mostly Underground Storage Tanks entries (18), the nearest Nitrate record about 2.3 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in Blackburn?
From about Oct 10 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Nov 9 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Nov 9. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Blackburn's scale — its 7a band and its 233-day season. Your yard writes its own version of Blackburn's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Blackburn’s own scale
6 of the readings below were taken at Blackburn's own scale — its own ~233-day season between 28°F freezes, the 189 acres it covers and 38 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Blackburn's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Blackburn's own 28°F hard-freeze dates, about Mar 21 and Nov 9 and the ~233-day span between themNOAA 1991–2020 Climate Normals
- 38 documented contamination sites on the federal record near Blackburn, the closest Nitrate record about 2.3 miles out from the town centreFederal environmental registers
- Blackburn's boundary and the 189 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~233-day seasonGrowable Ground crop-matching engine
- The ecoregion at Blackburn's own centroid, the Central Great PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Blackburn's 189 acres read through its county's SSURGO summaryfrom Pawnee County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Pawnee County
- The growing challenges every Oklahoma grower plans around — written at state scale, so they stay on the state guidefrom Oklahoma
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Pawnee County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Blackburn's 189 acreswhy one lot differs from the next →
- Which side of Blackburn you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 189 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 2.3 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Blackburn-wide figureread your own land →
More in Oklahoma
Wider growing context
What grows across OklahomaBlackburn sits outside our named growing regions, so Oklahoma as a whole is its closest context here.