St. Thomas, Missouri, sits in USDA hardiness zone 6b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Growers here do well with cabbage, hazelnut, lavender, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in St. Thomas, 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 St. Thomas 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 St. Thomas — soil, climate, flood, and parcel records. How we handle your address.
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St. Thomas — the short answer
St. Thomas, Missouri: USDA zone 6b, about 222 days between hard freezes, across 627 acres of town.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 29
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~222
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 627 acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 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 6b is St. Thomas's average, not your lot's — a low corner or a tree line moves it. Against St. Thomas's 222-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in St. Thomas
Each reading below is measured for St. Thomas itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSt. Thomas runs about 222 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
MeasuredSt. Thomas sits in USDA hardiness zone 6b.
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 St. Thomas is in
St. Thomas sits in the Ozark Highlands — EPA Level III, inside the wider Eastern Temperate Forests. That is read at St. Thomas's own centroid, and it is not what its county reads: Cole County is mostly Interior River Valleys and Hills. The wider page above you is answering a different question about different ground.
What Grows in St. Thomas
Every plant below cleared St. Thomas's own zone 6b and its 222-day season. Each card opens that plant's Missouri profile. How we score.
Is it too late to plant in St. Thomas?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 29 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 6 — 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 St. Thomas
Survey cells within 31 miles of St. Thomas checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 318 miles off. What to watch for.
What's on the federal record near St. Thomas
Closest first, within ~10 miles of St. Thomas. Listing isn't leaking, and distance isn't exposure.
- T42N R12W 23DCD1Nitrate · 500 ft
- GRONERS GARAGEUnderground Storage Tanks · 1200 ft
- B & K QUICK SHOPPEUnderground Storage Tanks · 0.9 mi
- KOETTING STOREUnderground Storage Tanks · 2.5 mi
- Blue Jack MineMining · 3.5 mi
- TWO P LIVESTOCK CO INCCAFO · 3.8 mi
- MFA EXCHANGEUnderground Storage Tanks · 4.4 mi
- DIAMOND FEEDSUnderground Storage Tanks · 4.5 mi
- META OIL INC #506 - SOLDUnderground Storage Tanks · 4.5 mi
- MFA EXCHANGE - METAUnderground Storage Tanks · 4.6 mi
- META MAINT BLDGUnderground Storage Tanks · 4.6 mi
- MASSMAN'S GROCERY & SPORTING GOODSUnderground Storage Tanks · 4.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from St. Thomas'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 St. Thomas.
Sources Checked
within ~10 miles of St. Thomas
Severity Distribution
within ~10 miles of St. Thomas
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around St. Thomas, two things run higher than the national average within ~10 miles of St. Thomas — CAFO (3 sites) and Mining (11 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in St. Thomas
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 St. Thomas average
Your land is one point inside St. Thomas
Everything above resolves to St. Thomas as a whole — one PHZM band and one 28°F frost record, read across 627 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 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 St. Thomas Average
St. Thomas Average
- ●USDA Zones 6b, averaged across St. Thomas
- ●One soil character for all of St. Thomas
- ●Frost dates read at St. Thomas's scale: Mar 29 to Nov 6
YOUR Parcel
- ✓Your exact zone, not St. Thomas's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in St. Thomas
Pull a site-specific report for your exact address in St. Thomas, Missouri — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that St. Thomas averages can't show:
We read public map data around St. Thomas — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the St. Thomas average
How we know this about St. Thomas
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. Thomas’s own record; 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 St. Thomas
When does frost risk typically end in St. Thomas?
The last hard freeze (28°F) in St. Thomas typically lands around Mar 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 Apr 19.
When is the first frost in St. Thomas?
The first hard freeze (28°F) in St. Thomas typically arrives around Nov 6, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 23, so the watching starts about Oct 7 — about 222 days after the spring freeze cleared.
How long is the growing season in St. Thomas?
Measured between 28°F hard freezes, St. Thomas sees about 222 frost-free days — roughly Mar 29 through Nov 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 19 to Oct 23, about 187 days.
Is the soil safe to grow vegetables in St. Thomas?
The federal record around St. Thomas is a meaningful one — 53 documented sites, mostly Underground Storage Tanks entries (27), the nearest Nitrate 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 St. Thomas?
From about Oct 7 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 Nov 6 (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 Nov 6. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at St. Thomas's scale — its 6b band and its 222-day season. Your yard writes its own version of St. Thomas'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 St. Thomas’s own scale
7 of the readings below were taken at St. Thomas's own scale — its own ~222-day season between 28°F freezes, the 627 acres it covers and 53 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- St. Thomas's own USDA hardiness band, zones 6bUSDA PHZM 2023
- St. Thomas's own 28°F hard-freeze dates, about Mar 29 and Nov 6 and the ~222-day span between themNOAA 1991–2020 Climate Normals
- 53 documented contamination sites on the federal record near St. Thomas, the closest Nitrate record under a tenth of a mile out from the town centreFederal environmental registers
- St. Thomas's boundary and the 627 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~222-day seasonGrowable Ground crop-matching engine
- St. Thomas sits in the Ozark Highlands — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
- Lanternfly survey cells around St. Thomas checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so St. Thomas's 627 acres read through its county's SSURGO summaryfrom Cole County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Cole County
- The growing challenges every Missouri grower plans around — written at state scale, so they stay on the state guidefrom Missouri
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Cole County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among St. Thomas's 627 acreswhy one lot differs from the next →
- Which side of St. Thomas you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 627 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate 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 St. Thomas-wide figureread your own land →
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