Helena, Oklahoma, sits in USDA hardiness zone 7a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Among the crops suited to this profile: cabbage, hazelnut, california poppy, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Even in Helena, 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 Helena 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 Helena — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Helena — the short answer
Helena, Oklahoma: USDA zone 7a, about 222 days between hard freezes, across 261 acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 31
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 8
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~222
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 261 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 Helena's average, not your lot's — a low corner or a tree line moves it. Against Helena's 222-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Helena
Each reading below is measured for Helena itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHelena runs about 222 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
MeasuredHelena 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 Helena is in
Helena sits in the Central Great Plains — EPA Level III, inside the wider Great Plains. That is read at Helena's own centroid rather than borrowed from Alfalfa County.
What Grows in Helena
Every plant below cleared Helena's own zone 7a and its 222-day season. Each card opens that plant's Oklahoma profile. How we score.
Is it too late to plant in Helena?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Mar 3; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 31 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 8 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
What's on the federal record near Helena
Closest first, within ~10 miles of Helena. Listing isn't leaking, and distance isn't exposure.
- Boehs RentalUnderground Storage Tanks · 500 ft
- Gene W. JantzUnderground Storage Tanks · 650 ft
- NORMANS WELDING & REPAIRBrownfields · 1200 ft
- Shepherd Key PumpUnderground Storage Tanks · 1300 ft
- James Crabtree Correctional CtrUnderground Storage Tanks · 1300 ft
- Helena Mini-MartUnderground Storage Tanks · 2200 ft
- 24N-11W-26 BBB 1Nitrate · 4.6 mi
- 23N-10W-07 BBC 1Nitrate · 4.7 mi
- SKELETON CREEK LLCBrownfields · 5.4 mi
- 24N-09W-21 C 1Nitrate · 5.5 mi
- Farmers Coop ExchangeUnderground Storage Tanks · 6.6 mi
- The Farmers Exchange Of GoltryUnderground Storage Tanks · 6.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Helena'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 Helena.
Total Sites
37
within ~10 miles of Helena
Risk Level
Low
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
within ~10 miles of Helena
Severity Distribution
within ~10 miles of Helena
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Helena, Nitrate runs higher than the national average — 16 sites within ~10 miles of Helena. 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 Helena
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 Helena average
Your land is one point inside Helena
Everything above resolves to Helena as a whole — one PHZM band and one 28°F frost record, read across 261 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 Helena Average
Helena Average
- ●USDA Zones 7a, averaged across Helena
- ●One soil character for all of Helena
- ●Frost dates read at Helena's scale: Mar 31 to Nov 8
YOUR Parcel
- ✓Your exact zone, not Helena's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Helena
Pull a site-specific report for your exact address in Helena, Oklahoma — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Helena averages can't show:
We read public map data around Helena — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Helena average
How we know this about Helena
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 Helena’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 Helena
When does frost risk typically end in Helena?
The last hard freeze (28°F) in Helena typically lands around Mar 31, 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 21.
When is the first frost in Helena?
The first hard freeze (28°F) in Helena typically arrives around Nov 8, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 25, so the watching starts about Oct 9 — about 222 days after the spring freeze cleared.
How long is the growing season in Helena?
Measured between 28°F hard freezes, Helena sees about 222 frost-free days — roughly Mar 31 through Nov 8, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 21 to Oct 25, about 187 days.
Is the soil safe to grow vegetables in Helena?
The federal record around Helena is light — 37 documented sites across the 9 federal source types we checked, mostly Underground Storage Tanks entries (17), the nearest Underground Storage Tanks record under a tenth of a mile out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do I protect my plants from frost in Helena?
From about Oct 9 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 8 (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 8. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Helena's scale — its 7a band and its 222-day season. Your yard writes its own version of Helena'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 Helena’s own scale
6 of the readings below were taken at Helena's own scale — its own ~222-day season between 28°F freezes, the 261 acres it covers and 37 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Helena's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Helena's own 28°F hard-freeze dates, about Mar 31 and Nov 8 and the ~222-day span between themNOAA 1991–2020 Climate Normals
- 37 documented contamination sites on the federal record near Helena, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Helena's boundary and the 261 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~222-day seasonGrowable Ground crop-matching engine
- The ecoregion at Helena's own centroid, the Central Great PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Helena's 261 acres read through its county's SSURGO summaryfrom Alfalfa County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Alfalfa 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 Alfalfa County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Helena's 261 acreswhy one lot differs from the next →
- Which side of Helena you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 261 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile 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 Helena-wide figureread your own land →
More in Oklahoma
Wider growing context
What grows across OklahomaHelena sits outside our named growing regions, so Oklahoma as a whole is its closest context here.