Old Jefferson, Louisiana, sits in USDA hardiness zone 9a — a zone band wide enough that plant choice, not possibility, is the interesting question.
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.
Even in Old Jefferson, 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 Old Jefferson 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 Old Jefferson — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Old Jefferson — the short answer
Old Jefferson, Louisiana: USDA zone 9a, about 300 days between hard freezes, across 2K acres of town.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 7
- East Baton Rouge Parish normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 4
- East Baton Rouge Parish normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~300
- East Baton Rouge Parish normal — NOAA 1991–2020, nearest to this town
- Town area
- 2K 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 East Baton Rouge Parish’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Old Jefferson's average, not your lot's — a low corner or a tree line moves it. Against Old Jefferson's 300-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Old Jefferson
Each reading below is measured for Old Jefferson itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsOld Jefferson runs about 300 days between hard freezes (read from East Baton Rouge Parish, the closest normal to Old Jefferson) — 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
MeasuredOld Jefferson 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 Old Jefferson is in
Old Jefferson sits in the Mississippi Valley Loess Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Old Jefferson's own centroid rather than borrowed from East Baton Rouge Parish.
What Grows in Old Jefferson
Every plant below cleared Old Jefferson's own zone 9a and its 300-day season. Each card opens that plant's Louisiana profile. How we score.
Is it too late to plant in Old Jefferson?
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 10; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 7 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 4 — 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 Old Jefferson
Closest first, within ~10 miles of Old Jefferson. Listing isn't leaking, and distance isn't exposure.
- FERRARA TRANSPORT SERVICES LLCBrownfields · 2100 ft
- EB-796Nitrate · 0.5 mi
- Jefferson Highway Right-of-WayUnderground Storage Tanks · 0.6 mi
- Circle K #6801Underground Storage Tanks · 0.6 mi
- Lindig LawrenceUnderground Storage Tanks · 0.7 mi
- GRAPHIC SOURCE THEBrownfields · 0.7 mi
- St George Fire Station #63Underground Storage Tanks · 0.7 mi
- SHENANDOAH SOUTH VETERINARY HOSPITALBrownfields · 0.8 mi
- Circle K #6797Underground Storage Tanks · 0.8 mi
- GROUP CONTRACTORS LLCBrownfields · 0.8 mi
- Doyle Electric CoUnderground Storage Tanks · 0.9 mi
- ROY LEWIS CARPENTRY LLCBrownfields · 0.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Old Jefferson'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 Old Jefferson.
Total Sites
2,619
within ~10 miles of Old Jefferson
Risk Level
Elevated
Highest-severity
8 Superfund sites
Sources Checked
within ~10 miles of Old Jefferson
Severity Distribution
within ~10 miles of Old Jefferson
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Old Jefferson, Brownfields runs higher than the national average — 1,492 sites within ~10 miles of Old Jefferson. That's not a problem with your land — it's information about it.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Check your specific parcel in Old Jefferson
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 Old Jefferson average
Your land is one point inside Old Jefferson
Everything above resolves to Old Jefferson as a whole — one PHZM band, read across 2K acres, with hard-freeze dates borrowed from East Baton Rouge 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 Old Jefferson Average
Old Jefferson Average
- ●USDA Zones 9a, averaged across Old Jefferson
- ●One soil character for all of Old Jefferson
- ●Frost dates read at Old Jefferson's scale: Feb 7 to Dec 4
YOUR Parcel
- ✓Your exact zone, not Old Jefferson's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Old Jefferson
Pull a site-specific report for your exact address in Old Jefferson, Louisiana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Old Jefferson averages can't show:
We read public map data around Old Jefferson — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Old Jefferson average
How we know this about Old Jefferson
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 East Baton Rouge 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 Old Jefferson
When does frost risk typically end in Old Jefferson?
The last hard freeze (28°F) in Old Jefferson typically lands around Feb 7, 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 28.
When is the first frost in Old Jefferson?
The first hard freeze (28°F) in Old Jefferson typically arrives around Dec 4, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 20, so the watching starts about Nov 4 — about 300 days after the spring freeze cleared.
How long is the growing season in Old Jefferson?
Measured between 28°F hard freezes, Old Jefferson sees about 300 frost-free days — roughly Feb 7 through Dec 4, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 28 to Nov 20, about 265 days.
Is the soil safe to grow vegetables in Old Jefferson?
The federal record around Old Jefferson is a meaningful one — 2,619 documented sites, mostly Brownfields entries (1,492), the nearest Brownfields record about 0.4 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 Old Jefferson?
From about Nov 4 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 4 (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 4. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Old Jefferson's scale — its 9a band and its 300-day season. Your yard writes its own version of Old Jefferson'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 Old Jefferson’s own scale
5 of the readings below were taken at Old Jefferson's own scale — the 2,252 acres it covers and 2,619 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Old Jefferson's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 2,619 documented contamination sites on the federal record near Old Jefferson, the closest Brownfields record about 0.4 miles out from the town centreFederal environmental registers
- Old Jefferson's boundary and the 2,252 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~300-day seasonGrowable Ground crop-matching engine
- The ecoregion at Old Jefferson's own centroid, the Mississippi Valley Loess PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Old Jefferson has no normal of its own, so its county's is the closest measured readfrom East Baton Rouge Parish
- Soil character — no town-scale survey exists, so Old Jefferson's 2,252 acres read through its county's SSURGO summaryfrom East Baton Rouge County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom East Baton Rouge 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 East Baton Rouge County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Old Jefferson's 2,252 acreswhy one lot differs from the next →
- Which side of Old Jefferson you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,252 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.4 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 Old Jefferson-wide figureread your own land →
More in Louisiana
Wider growing context
What grows across LouisianaOld Jefferson sits outside our named growing regions, so Louisiana as a whole is its closest context here.
Nearby growing guides