Slidell, Louisiana, sits in USDA hardiness zone 9a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
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 Slidell, 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 Slidell 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 Slidell — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Slidell — the short answer
Slidell, Louisiana: USDA zone 9a, about 300 days between hard freezes, across 10K acres of city.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 8
- St. Tammany Parish normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 5
- St. Tammany Parish normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~300
- St. Tammany Parish normal — NOAA 1991–2020, nearest to this town
- City area
- 10K 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. Tammany Parish’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Slidell's average, not your lot's — a low corner or a tree line moves it. Against Slidell's 300-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Slidell
Each reading below is measured for Slidell itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsSlidell runs about 300 days between hard freezes (read from St. Tammany Parish, the closest normal to Slidell) — 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
MeasuredSlidell 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 Slidell is in
Slidell sits in the Southern Coastal Plain — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Slidell's own centroid rather than borrowed from St. Tammany Parish.
What Grows in Slidell
Every plant below cleared Slidell'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 Slidell?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Jan 11; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 8 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 5 — long-season crops need about 90 days of runway, quick greens only 30. Here the calendar nearly circles: cool-season crops take the winter shift, and the next window is always close.
What's on the federal record near Slidell
Closest first, within ~10 miles of Slidell. Listing isn't leaking, and distance isn't exposure.
- DOLLAR GENERAL #10500Brownfields · 350 ft
- BIG LOTSBrownfields · 850 ft
- SAVE-A-LOT #5721Brownfields · 850 ft
- GLY-TECH SERVICES INC- SLIDELLBrownfields · 900 ft
- PIPELINE SOLUTIONS LLCBrownfields · 950 ft
- ST-9Nitrate · 1000 ft
- ALLIANCE LASERBrownfields · 1200 ft
- RITE AID PHARMACY #7290Brownfields · 1300 ft
- Northside PlazaUnderground Storage Tanks · 1400 ft
- TexacoUnderground Storage Tanks · 1500 ft
- Circle K #2896Underground Storage Tanks · 1500 ft
- Precision TuneUnderground Storage Tanks · 1600 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Slidell'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 Slidell.
Sources Checked
within ~10 miles of Slidell
Severity Distribution
within ~10 miles of Slidell
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Slidell, two things run higher than the national average within ~10 miles of Slidell — PFAS (8 sites) and Brownfields (370 sites). That's not a problem with your land — it's information about it.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Check your specific parcel in Slidell
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 Slidell average
Your land is one point inside Slidell
Everything above resolves to Slidell as a whole — one PHZM band, read across 10K acres, with hard-freeze dates borrowed from St. Tammany 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 Slidell Average
Slidell Average
- ●USDA Zones 9a, averaged across Slidell
- ●One soil character for all of Slidell
- ●Frost dates read at Slidell's scale: Feb 8 to Dec 5
YOUR Parcel
- ✓Your exact zone, not Slidell's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Slidell
Pull a site-specific report for your exact address in Slidell, Louisiana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Slidell averages can't show:
We read public map data around Slidell — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Slidell average
How we know this about Slidell
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 St. Tammany 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 Slidell
When does frost risk typically end in Slidell?
The last hard freeze (28°F) in Slidell typically lands around Feb 8, 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 1.
When is the first frost in Slidell?
The first hard freeze (28°F) in Slidell typically arrives around Dec 5, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 21, so the watching starts about Nov 5 — about 300 days after the spring freeze cleared.
How long is the growing season in Slidell?
Measured between 28°F hard freezes, Slidell sees about 300 frost-free days — roughly Feb 8 through Dec 5, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 1 to Nov 21, about 265 days.
Is the soil safe to grow vegetables in Slidell?
The federal record around Slidell is a meaningful one — 646 documented sites, mostly Brownfields entries (370), the nearest Brownfields 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 Slidell?
From about Nov 5 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 5 (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 5. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Slidell's scale — its 9a band and its 300-day season. Your yard writes its own version of Slidell'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 Slidell’s own scale
5 of the readings below were taken at Slidell's own scale — the 9,737 acres it covers and 646 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Slidell's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 646 documented contamination sites on the federal record near Slidell, the closest Brownfields record under a tenth of a mile out from the town centreFederal environmental registers
- Slidell's boundary and the 9,737 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 Slidell's own centroid, the Southern Coastal PlainUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Slidell has no normal of its own, so its county's is the closest measured readfrom St. Tammany Parish
- Soil character — no town-scale survey exists, so Slidell's 9,737 acres read through its county's SSURGO summaryfrom St. Tammany County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom St. Tammany 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. Tammany County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Slidell's 9,737 acreswhy one lot differs from the next →
- Which side of Slidell you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 9,737 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields 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 Slidell-wide figureread your own land →
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