St. Helena Parish, in Louisiana, sits in USDA hardiness zone 9a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
The conditions favor artichoke, fig, california poppy, and cabbage, among others — though every individual site edits that list with its own soil, sun, and drainage.
St. Helena Parish lies within the Florida Parishes — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
St. Helena Parish holds more than one microclimate.
Soils and elevations shift across St. Helena Parish, so your frost dates and drainage aren't the county average. 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 St. Helena Parish — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
St. Helena Parish — the short answer
St. Helena Parish, Louisiana: USDA zone 9a, about 285 days between hard freezes, across 261K acres.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 17
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 29
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~285
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 261K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 9a is St. Helena Parish's average, not your lot's — a low corner or a tree line moves it. Against St. Helena Parish's 285-day season, see what your own ground reads.
Heat and winter chill in St. Helena Parish
Across a year, St. Helena Parish accumulates about 6,079 growing degree days above 50°F, about 217 fewer than the middle Louisiana county — ahead of 25 of Louisiana’s 64 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Winter banks about 669 hours below 45°F, 57 more than the Louisiana middle of 612. Chill is what tells a fruit tree its dormancy is over, and it is set by climate rather than by anything you can build.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in St. Helena County
Across St. Helena County, the ground is predominantly Ultisols, where Tangi, Ruston, and Ochlockonee are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 5.0–5.3, strongly acidic. Rainfall drains through hydrologic group B soils.
Soil order
Ultisols
Drainage
Well drained
Prime farmland
37%
Hydric soils
26%
Soil still varies lot by lot — soil types explained.
How the ground varies across St. Helena Parish
The USDA soil survey maps 47% of St. Helena Parish as well drained — but another 53% drains differently: 36% moderately well drained, 9% poorly drained.
Tangi is the most extensive named soil at 27% of mapped acres, then Ruston (14%) and Ochlockonee (10%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in St. Helena Parish
Each reading below is measured for St. Helena Parish itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across St. Helena Parish are well drained, in hydrologic group B — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across St. Helena Parish runs about pH 5.0–5.3, on the acidic side.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Wet ground
MeasuredAbout 26% of St. Helena Parish is mapped as hydric — wetland — soil.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Season length
MeasuredSt. Helena Parish runs about 285 days between hard freezes — close to year-round growing.
Frost is rarely the limit here; winter plantings are as real as summer ones, and the harder question is which crops shrug off the summer heat.
Grow cool-season crops through the mild winter, and choose heat-tolerant varieties for the summer beds.
NOAA 1991–2020 Climate Normals
The kind of country St. Helena Parish is in
St. Helena Parish spans 2 EPA Level III ecoregions — Southeastern Plains (84%) and Mississippi Valley Loess Plains (13%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in St. Helena Parish
We scored all 1,086 plants against St. Helena Parish's own USDA zone 9a and its own 285-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Louisiana profile.
Is it too late to plant in St. Helena Parish?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Jan 20; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 17 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 29 — long-season crops need about 90 days of runway, quick greens only 30. And with a calendar this mild, the honest answer is that planting barely stops — winter opens seasons colder regions never see.
What gets applied to farmland in St. Helena Parish
USGS estimates 4,018 lb of 2,4-d on St. Helena Parish farmland in 2019, its largest by weight, ahead of Glyphosate (2,138 lb) and Triclopyr (782 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across St. Helena County — and how to grow with it.
We checked the federal record across St. Helena County — 124 documented sites across 5 of the 9 source types we track.
The most significant on record: 2 Toxics Release Inventory facilities. Active industrial facilities reporting chemical releases to air, water, and land.
The federal record across St. Helena County is a modest one — a typical footprint for a growing area. Nothing here calls for alarm; it's worth knowing which recorded sites sit closest to where you grow, and each one on the map carries its type and location. If one turns out to be a near neighbor, a one-time soil test settles the question.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near St. Helena Parish
Closest first, across St. Helena County. Listing isn't leaking, and distance isn't exposure.
- Hall's GroceryUnderground Storage Tanks · 0.6 mi
- Meshee's 4-Way StopUnderground Storage Tanks · 1.0 mi
- Dollar DiscountUnderground Storage Tanks · 1.1 mi
- Greensburg AmocoUnderground Storage Tanks · 1.8 mi
- Hilltop General MerchandiseUnderground Storage Tanks · 1.8 mi
- Speedy Too GroceryUnderground Storage Tanks · 1.9 mi
- LADOTD - Greensburg Maintenance UnitUnderground Storage Tanks · 2.1 mi
- SOUTHLAND STEL FABRICATORS INC - GREENSBURG FACILITYBrownfields · 2.3 mi
- SOUTHLAND STEEL FABRICATORSToxics Release Inventory · 2.3 mi
- NORTHSHORE TECH COMM COLLEGE FLORIDA PARISHESBrownfields · 2.3 mi
- Hank's Mobil Deli LLCUnderground Storage Tanks · 2.3 mi
- SH-5Nitrate · 2.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from St. Helena Parish'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 St. Helena Parish.
Total Sites
124
across St. Helena County
Risk Level
Moderate
Highest-severity
2 Toxics Release Inventory facilities
Sources Checked
across St. Helena County
Severity Distribution
across St. Helena County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around St. Helena Parish, Nitrate runs higher than the national average — 50 sites across St. Helena County. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 St. Helena Parish
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 St. Helena Parish average
Your land is one point inside St. Helena Parish
Everything above resolves to St. Helena Parish as a whole — one PHZM band and one county frost record, read across 261K 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 county 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 county average.
Your Lot vs the St. Helena Parish Average
St. Helena Parish Average
- ●USDA Zones 9a, averaged across St. Helena Parish
- ●One soil character for all of St. Helena Parish
- ●Frost dates read at St. Helena Parish's scale: Feb 17 to Nov 29
YOUR Parcel
- ✓Your exact zone, not St. Helena Parish's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in St. Helena Parish
Pull a site-specific report for your exact address in St. Helena Parish, Louisiana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that St. Helena Parish averages can't show:
We read public map data around St. Helena Parish — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the St. Helena Parish average
How we know this about St. Helena Parish
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where St. Helena Parish carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about St. Helena Parish
When does frost risk typically end in St. Helena Parish?
The last hard freeze (28°F) in St. Helena Parish typically lands around Feb 17, 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 Mar 10.
How long is the growing season in St. Helena Parish?
Measured between 28°F hard freezes, St. Helena Parish sees about 285 frost-free days — roughly Feb 17 through Nov 29, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 10 to Nov 15, about 250 days.
Is the soil safe to grow vegetables in St. Helena Parish?
The federal record around St. Helena Parish shows 124 documented sites, mostly Underground Storage Tanks entries (55), the nearest Underground Storage Tanks record about 0.6 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
Everything above is measured at St. Helena Parish's scale — its 9a band and its 285-day season. Your yard writes its own version of St. Helena Parish's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Louisiana's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at St. Helena Parish’s own scale
8 of the readings below were taken at St. Helena Parish's own scale — its own ~285-day span between 28°F freezes, the 3 most extensive soil series mapped here and 124 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- St. Helena Parish's own USDA hardiness band, zones 9aUSDA PHZM 2023
- St. Helena Parish's own 28°F hard-freeze dates and its ~285-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in St. Helena ParishUSDA NRCS SSURGO
- 124 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.6 miles outFederal environmental registers
- St. Helena Parish's boundary and the 261,457 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~285-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions St. Helena Parish spans, Southeastern Plains the largestUS EPA Level III Ecoregions
- Which agricultural compounds go onto St. Helena Parish farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Louisiana grower plans around — written at state scale, so they stay on the state guidefrom Louisiana
What this page can’t tell you
- How the season shifts across St. Helena Parish — the ~285 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among St. Helena Parish's 261,457 acreswhy one lot differs from the next →
- Which of those 124 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over St. Helena Parishread your own land →