Sulphur, 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.
Among the crops suited to this profile: artichoke, fig, california poppy, and cabbage. The site-level story — soil, sun, drainage — decides the rest.
Even in Sulphur, 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 Sulphur 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 Sulphur — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Sulphur — the short answer
Sulphur, Louisiana: USDA zone 9a, about 313 days between hard freezes, across 7K acres of city.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 30
- Calcasieu Parish normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 9
- Calcasieu Parish normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~313
- Calcasieu Parish normal — NOAA 1991–2020, nearest to this town
- City area
- 7K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. No 30-year normal resolves at this town’s own centroid, so the hard-freeze dates are Calcasieu Parish’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Sulphur's average, not your lot's — a low corner or a tree line moves it. Against Sulphur's 313-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Sulphur
Each reading below is measured for Sulphur itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsSulphur runs about 313 days between hard freezes (read from Calcasieu Parish, the closest normal to Sulphur) — 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
Winter hardiness
MeasuredSulphur sits in USDA hardiness zone 9a.
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 Sulphur is in
Sulphur sits in the Western Gulf Coastal Plain — EPA Level III, inside the wider Great Plains. That is read at Sulphur's own centroid rather than borrowed from Calcasieu Parish.
What Grows in Sulphur
Every plant below cleared Sulphur's own zone 9a and its 313-day season. Each card opens that plant's Louisiana profile. How we score.
Is it too late to plant in Sulphur?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Jan 2; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jan 30 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 9 — 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's on the federal record near Sulphur
Closest first, within ~10 miles of Sulphur. Listing isn't leaking, and distance isn't exposure.
- Sulphur City of Water DeptUnderground Storage Tanks · 250 ft
- Cu-706Nitrate · 550 ft
- OAK PARK CHIROPRACTIC CLINICBrownfields · 850 ft
- Calcasieu Parish Sheriff DepartmentUnderground Storage Tanks · 950 ft
- DOLLAR GENERAL STORE #22891Brownfields · 1000 ft
- Kroger #747 Kwik ShopUnderground Storage Tanks · 1000 ft
- ADV HLTH CNTR INC DBA FIRST CHIROPBrownfields · 1000 ft
- Super Saver #4Underground Storage Tanks · 1100 ft
- SALLY BEAUTY #2670Brownfields · 1300 ft
- Calcasieu Parish Sheriff's Office - West Calcasieu Law EnforcementUnderground Storage Tanks · 1400 ft
- I MEDBrownfields · 1400 ft
- PETSENSE STORE #7162Brownfields · 1500 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Sulphur'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 Sulphur.
Sources Checked
within ~10 miles of Sulphur
Severity Distribution
within ~10 miles of Sulphur
Highest-Severity Sites
Know Before You Grow
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •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.
Check your specific parcel in Sulphur
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 Sulphur average
Your land is one point inside Sulphur
Everything above resolves to Sulphur as a whole — one PHZM band, read across 7K acres, with hard-freeze dates borrowed from Calcasieu Parish’s record because no 30-year normal resolves at this city’s own centroid. 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 city 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 Sulphur Average
Sulphur Average
- ●USDA Zones 9a, averaged across Sulphur
- ●One soil character for all of Sulphur
- ●Frost dates read at Sulphur's scale: Jan 30 to Dec 9
YOUR Parcel
- ✓Your exact zone, not Sulphur's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Sulphur
Pull a site-specific report for your exact address in Sulphur, Louisiana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Sulphur averages can't show:
We read public map data around Sulphur — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Sulphur average
How we know this about Sulphur
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Calcasieu Parish’s record, because none resolves here; 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 city grain anywhere on this page — there is no city-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 Sulphur
When does frost risk typically end in Sulphur?
The last hard freeze (28°F) in Sulphur typically lands around Jan 30, 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 Feb 20.
When is the first frost in Sulphur?
The first hard freeze (28°F) in Sulphur typically arrives around Dec 9, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 25, so the watching starts about Nov 9 — about 313 days after the spring freeze cleared.
How long is the growing season in Sulphur?
Measured between 28°F hard freezes, Sulphur sees about 313 frost-free days — roughly Jan 30 through Dec 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 20 to Nov 25, about 278 days.
Is the soil safe to grow vegetables in Sulphur?
The federal record around Sulphur is a meaningful one — 1,417 documented sites, mostly Brownfields entries (672), the nearest Underground Storage Tanks record under a tenth of a mile 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 Sulphur?
From about Nov 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 Dec 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 Dec 9. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Sulphur's scale — its 9a band and its 313-day season. Your yard writes its own version of Sulphur'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 Sulphur’s own scale
5 of the readings below were taken at Sulphur's own scale — the 7,190 acres it covers and 1,417 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Sulphur's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 1,417 documented contamination sites on the federal record near Sulphur, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Sulphur's boundary and the 7,190 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~313-day seasonGrowable Ground crop-matching engine
- The ecoregion at Sulphur's own centroid, the Western Gulf Coastal PlainUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Sulphur has no normal of its own, so its county's is the closest measured readfrom Calcasieu Parish
- Soil character — no town-scale survey exists, so Sulphur's 7,190 acres read through its county's SSURGO summaryfrom Calcasieu County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Calcasieu County
- The growing challenges every Louisiana grower plans around — written at state scale, so they stay on the state guidefrom Louisiana
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Calcasieu County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Sulphur's 7,190 acreswhy one lot differs from the next →
- Which side of Sulphur you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 7,190 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 Sulphur-wide figureread your own land →
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