Union, Louisiana, sits in USDA hardiness zone 9a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Growers here do well with artichoke, fig, california poppy, and cabbage — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Union, 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 Union 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 Union — soil, climate, flood, and parcel records. How we handle your address.
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Union — the short answer
Union, Louisiana: USDA zone 9a, about 316 days between hard freezes, across 6K acres of town.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 29
- St. James Parish normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 11
- St. James Parish normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~316
- St. James Parish normal — NOAA 1991–2020, nearest to this town
- Town area
- 6K 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 St. James Parish’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Union's average, not your lot's — a low corner or a tree line moves it. Against Union's 316-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Union
Each reading below is measured for Union itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsUnion runs about 316 days between hard freezes (read from St. James Parish, the closest normal to Union) — 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
MeasuredUnion 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 Union is in
Union sits in the Mississippi Alluvial Plain — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Union's own centroid rather than borrowed from St. James Parish.
What Grows in Union
Every plant below cleared Union's own zone 9a and its 316-day season. Each card opens that plant's Louisiana profile. How we score.
Is it too late to plant in Union?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Jan 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jan 29 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 11 — 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 Union
Closest first, within ~10 miles of Union. Listing isn't leaking, and distance isn't exposure.
- TRANSFER SYSTEMS INCBrownfields · 0.6 mi
- ARRMAX PRODUCTS INC - CONVENT FACILITYBrownfields · 0.8 mi
- ST JAMES STEVEDORING CO INCBrownfields · 0.9 mi
- Maintenance ShopUnderground Storage Tanks · 0.9 mi
- River Road Super StopUnderground Storage Tanks · 0.9 mi
- YARA NORTH AMERICA INCBrownfields · 1.1 mi
- MILLENNIUM GALVANIZING LLCBrownfields · 1.2 mi
- MILLENNIUM GALVANIZING LLCToxics Release Inventory · 1.2 mi
- TRANSCONTINENTAL GAS P/L COMP STA 63Brownfields · 1.3 mi
- Transcontinental Gas Pipe Line Co LLC (TRANSCO) - Station 63 Natural Gas Compressor StationUnderground Storage Tanks · 1.3 mi
- SJ-41Nitrate · 1.4 mi
- BENHARD GRAINToxics Release Inventory · 1.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Union'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 Union.
Sources Checked
within ~10 miles of Union
Severity Distribution
within ~10 miles of Union
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Union, PFAS runs higher than the national average — 5 sites within ~10 miles of Union. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check your specific parcel in Union
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 Union average
Your land is one point inside Union
Everything above resolves to Union as a whole — one PHZM band, read across 6K acres, with hard-freeze dates borrowed from St. James Parish’s record because no 30-year normal resolves at this town’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 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 Union Average
Union Average
- ●USDA Zones 9a, averaged across Union
- ●One soil character for all of Union
- ●Frost dates read at Union's scale: Jan 29 to Dec 11
YOUR Parcel
- ✓Your exact zone, not Union's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Union
Pull a site-specific report for your exact address in Union, Louisiana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Union averages can't show:
We read public map data around Union — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Union average
How we know this about Union
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 St. James 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 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 Union
When does frost risk typically end in Union?
The last hard freeze (28°F) in Union typically lands around Jan 29, 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 19.
When is the first frost in Union?
The first hard freeze (28°F) in Union typically arrives around Dec 11, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 27, so the watching starts about Nov 11 — about 316 days after the spring freeze cleared.
How long is the growing season in Union?
Measured between 28°F hard freezes, Union sees about 316 frost-free days — roughly Jan 29 through Dec 11, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 19 to Nov 27, about 281 days.
Is the soil safe to grow vegetables in Union?
The federal record around Union is a meaningful one — 559 documented sites, mostly Brownfields entries (251), the nearest Brownfields record about 0.6 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 Union?
From about Nov 11 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 11 (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 11. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Union's scale — its 9a band and its 316-day season. Your yard writes its own version of Union'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 Union’s own scale
5 of the readings below were taken at Union's own scale — the 6,109 acres it covers and 559 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Union's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 559 documented contamination sites on the federal record near Union, the closest Brownfields record about 0.6 miles out from the town centreFederal environmental registers
- Union's boundary and the 6,109 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~316-day seasonGrowable Ground crop-matching engine
- The ecoregion at Union's own centroid, the Mississippi Alluvial PlainUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Union has no normal of its own, so its county's is the closest measured readfrom St. James Parish
- Soil character — no town-scale survey exists, so Union's 6,109 acres read through its county's SSURGO summaryfrom St. James County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom St. James 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 St. James County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Union's 6,109 acreswhy one lot differs from the next →
- Which side of Union you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 6,109 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.6 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 Union-wide figureread your own land →
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