Smith County, in Tennessee, sits in USDA hardiness zone 7b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
The conditions favor cabbage, prickly pear, california poppy, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Smith County lies within the Nashville Basin — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Smith County holds more than one microclimate.
Soils and elevations shift across Smith County, 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 Smith County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Smith County — the short answer
Smith County, Tennessee: USDA zone 7b, about 228 days between hard freezes, across 201K acres.
- USDA zone
- 7b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 26
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 9
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~228
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 201K 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 7b is Smith County's average, not your lot's — a low corner or a tree line moves it. Against Smith County's 228-day season, see what your own ground reads.
Heat and winter chill in Smith County
Across a year, Smith County accumulates about 4,105 growing degree days above 50°F, about 8 fewer than the middle Tennessee county — ahead of 45 of Tennessee’s 95 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 2,104 hours below 45°F, 45 more than the Tennessee middle of 2,059. 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 Smith County
Across Smith County, the ground is predominantly Alfisols, where Ashwood, Mimosa, and Dellrose are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 5.6–6.3, moderately acidic. Rainfall drains through hydrologic group B soils.
Soil order
Alfisols
Drainage
Well drained
Prime farmland
12%
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
How the ground varies across Smith County
The USDA soil survey maps 85% of Smith County as well drained — but another 11% drains differently: 8% somewhat excessively drained, 3% moderately well drained.
Ashwood is the most extensive named soil at 23% of mapped acres, then Mimosa (21%) and Dellrose (9%).
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 Smith County
Each reading below is measured for Smith County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Smith County 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 Smith County runs about pH 5.6–6.3, 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
Season length
MeasuredSmith County runs about 228 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredSmith County sits in USDA hardiness zone 7b.
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 Smith County is in
Smith County sits in the Interior Plateau — EPA Level III, inside the wider Eastern Temperate Forests. One consistent ecological setting across the whole county.
What Grows in Smith County
We scored all 1,086 plants against Smith County's own USDA zone 7b and its own 228-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 Tennessee profile.
Is it too late to plant in Smith County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Feb 26; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 26 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 9 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
Documented around Smith County
Spotted lanternfly documented 30 miles from Smith County, first recorded 2023. What to watch for.
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Smith County
USGS estimates 22,374 lb of Glyphosate on Smith County farmland in 2019, its largest by weight, ahead of 2,4-d (20,865 lb) and Metolachlor & Metolachlor-s (7,793 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 Smith County — and how to grow with it.
We checked the federal record across Smith County — 154 documented sites across 7 of the 9 source types we track.
The most significant on record: 2 Superfund sites (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Smith County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Smith County
Closest first, across Smith County. Listing isn't leaking, and distance isn't exposure.
- CARTHAGE WATER SYSTEMPFAS · 25 ft
- Riverview Regional Medical CenterUnderground Storage Tanks · 0.7 mi
- HIGHPOINT HEALTH - RIVERVIEWBrownfields · 0.7 mi
- CUMBERLAND MINEToxics Release Inventory · 0.9 mi
- TRACTOR SUPPLY COMPANY #1321Brownfields · 0.9 mi
- Holladay Express Shop RealtyUnderground Storage Tanks · 0.9 mi
- Moss Service and Supply, Inc.Underground Storage Tanks · 1.0 mi
- ROBERTSHAW TENNESSEEToxics Release Inventory · 1.0 mi
- Cumberland MineMining · 1.0 mi
- Jack Shoulders Service StaUnderground Storage Tanks · 1.2 mi
- David KeithUnderground Storage Tanks · 1.2 mi
- Rock City GroceryUnderground Storage Tanks · 1.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Smith County'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 Smith County.
Total Sites
154
across Smith County
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
across Smith County
Severity Distribution
across Smith County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Smith County, two things run higher than the national average across Smith County — PFAS (4 sites) and Mining (23 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.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in Smith County
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 Smith County average
Your land is one point inside Smith County
Everything above resolves to Smith County as a whole — one PHZM band and one county frost record, read across 201K 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 Smith County Average
Smith County Average
- ●USDA Zones 7b, averaged across Smith County
- ●One soil character for all of Smith County
- ●Frost dates read at Smith County's scale: Mar 26 to Nov 9
YOUR Parcel
- ✓Your exact zone, not Smith County's 7b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Smith County
Pull a site-specific report for your exact address in Smith County, Tennessee — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Smith County averages can't show:
We read public map data around Smith County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Smith County average
How we know this about Smith County
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 Smith County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Smith County
When does frost risk typically end in Smith County?
The last hard freeze (28°F) in Smith County typically lands around Mar 26, 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 Apr 16.
How long is the growing season in Smith County?
Measured between 28°F hard freezes, Smith County sees about 228 frost-free days — roughly Mar 26 through Nov 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 16 to Oct 26, about 193 days.
Is the soil safe to grow vegetables in Smith County?
The federal record around Smith County is a meaningful one — 154 documented sites, mostly Underground Storage Tanks entries (95), the nearest PFAS 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.
Everything above is measured at Smith County's scale — its 7b band and its 228-day season. Your yard writes its own version of Smith County'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 Tennessee's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Smith County’s own scale
9 of the readings below were taken at Smith County's own scale — its own ~228-day span between 28°F freezes, the 3 most extensive soil series mapped here and 154 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Smith County's own USDA hardiness band, zones 7bUSDA PHZM 2023
- Smith County's own 28°F hard-freeze dates and its ~228-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Smith CountyUSDA NRCS SSURGO
- 154 documented contamination sites inside the county boundary, distance-sorted from its center — the closest PFAS record under a tenth of a mile outFederal environmental registers
- Smith County's boundary and the 201,138 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7b and a ~228-day seasonGrowable Ground crop-matching engine
- Smith County sitting wholly inside the Interior PlateauUS EPA Level III Ecoregions
- Open occurrence records documented in Smith County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Smith County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Tennessee grower plans around — written at state scale, so they stay on the state guidefrom Tennessee
What this page can’t tell you
- How the season shifts across Smith County — the ~228 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 Smith County's 201,138 acreswhy one lot differs from the next →
- Which of those 154 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 Smith Countyread your own land →