St. Louis Metro spans USDA hardiness zone 7a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Greater St. Louis runs a full half-zone warmer than the countryside wrapped around it: the city and St. Louis County both read USDA zone 7a with a 237-242-day frost-free season, while the neighboring St. Charles and Jefferson countryside holds at 6b (221-229 days). The Missouri-Mississippi confluence and the city's urban heat island push last frost earlier and first frost later — the longest growing season anywhere in Missouri outside the Bootheel — long enough to matter for heat-lovers and a real second planting. A short list that earns its place here — tomato, peach, dogwood, and grape — with any one site's soil, sun, and drainage making the final cut.
St. Louis Metro spans Missouri.
Your yard isn't all of St. Louis Metro.
St. Louis Metro spans USDA zones 7a, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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. Louis Metro — soil, climate, flood, and parcel records. How we handle your address.
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St. Louis Metro — the short answer
St. Louis Metro: USDA zones 7a, 237–242 frost-free days, in Missouri.
- USDA zones
- 7a
- USDA PHZM 2023, aggregated over the footprint
- Frost-free season
- 237–242 days
- NOAA Regional Climate Centers ACIS, 1991-2020
- Counties
- 2
- US Census TIGER/Line 2025
- Region type
- County cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. Where a region publishes no measured season, no season figure is shown.
Hardiness Zone Range
What Grows in St. Louis Metro
Plants matched to St. Louis Metro's USDA zones 7a, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of St. Louis Metro
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets St. Louis Metro’s USDA zones 7a — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across St. Louis Metro
The USDA soil survey maps this ground county by county. These are those records weighted by land area across one member county — this region’s own profile, not a state figure.
The ground is predominantly Alfisols, at 49% of mapped acres, followed by Entisols (36%), Mollisols (11%) and Inceptisols (4%). The most extensive named soils are Harvester, Menfro, and Winfield.
24% of those acres are well drained, and another 14% moderately well drained, 11% somewhat poorly drained. Topsoil pH runs 5.1–6.6 in that county’s own record. 7% of the footprint is classed prime farmland.
Soil order
Alfisols
Drainage
Well drained
Topsoil pH
5.1–6.6
Hydric soils
7%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. soil types explained.
USDA NRCS SSURGO via Soil Data Access · 1 of 2 footprint counties carry a summarizable record; the rest are absent from these figures rather than estimated.
What this means for growing in St. Louis Metro
The soil survey reads this ground county by county, and the readings above are those records summed across St. Louis Metro. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records24% of the mapped acres across St. Louis Metro are well drained — ground that drains quickly. That is area-weighted across its one mapped county.
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
From county recordsTopsoil across St. Louis Metro runs pH 5.1–6.6 — acidic in the one record covering it.
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
Safe to Grow Here?
What the federal record shows across St. Louis Metro — and how to grow with it.
Across St. Louis Metro's 2 counties the federal record holds 5,559 documented sites, mostly Underground Storage Tanks (3,274), Brownfields (1,612) and Toxics Release Inventory (397). The heaviest single county is St. Louis County, with 3,630.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to St. Louis Metro to see which records sit where you actually grow.
Sources Checked
Summed across the 2 counties in St. Louis Metro
A note from Gnorman
What an experienced grower watches for around here
In and around St. Louis Metro, Toxics Release Inventory runs higher than the national average — 397 sites across the 2 counties in St. Louis Metro. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside St. Louis Metro
Everything above resolves to St. Louis Metro as a whole — a footprint spanning USDA zones 7a. Your parcel sits in exactly one of them. 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 region 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 regional average.
Your Lot vs St. Louis Metro Average
St. Louis Metro Average
- ●USDA Zones 7a, averaged across St. Louis Metro
- ●One soil character for all of St. Louis Metro
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not St. Louis Metro's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in St. Louis Metro
Pull a site-specific report for your exact address in St. Louis Metro — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that St. Louis Metro averages can't show:
We read public map data around St. Louis Metro — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not St. Louis Metro average
How we know this about St. Louis Metro
The boundary: a cluster of neighboring counties. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about St. Louis Metro
What hardiness zone is St. Louis Metro?
St. Louis Metro spans USDA hardiness zones 7a, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in St. Louis Metro?
Measured between 28°F hard freezes, St. Louis Metro's counties mostly run 238 to 241 frost-free days, median 240 (NOAA Regional Climate Centers ACIS, 1991–2020, over 2 member counties). That 3-day spread is the honest read — no single season describes 2 counties, and each county guide below carries its own.
When does frost risk end in St. Louis Metro?
Across St. Louis Metro, the middle half of member counties see their last 28°F hard freeze between Mar 21 and Mar 21 (median Mar 21), and their first fall freeze between Nov 14 and Nov 17. Those are hard freezes, not the last light frost: tender transplants wait for about Apr 11, and elevation decides which end of a 0-day spread you garden in.
What grows well in St. Louis Metro?
St. Louis Metro's conditions suit plants such as Tomato, Peach, Dogwood, Grape, Blackberry. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is St. Louis Metro defined?
St. Louis Metro is defined here as a curated cluster of 2 neighboring counties that share a growing character. Growing regions have no official boundary, so this footprint is our published one — every county in it is named on this page.
Which states does St. Louis Metro cover?
St. Louis Metro spans Missouri. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Mississippi Delta, The Ozarks, North Missouri Glaciated Plains (Green Hills), and Missouri Bootheel share at least one state with St. Louis Metro. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at St. Louis Metro’s own scale
6 of the readings below were taken at St. Louis Metro's own scale — the zone 7a band across its footprint, a median 240-day season across its 2 counties and 5,559 documented federal contamination records across its 2 counties, 3,630 of them in St. Louis County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 7a aggregated across all 2 counties in the footprintUSDA PHZM 2023
- The boundary itself — the 2 counties this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 2 counties run 238 to 241 frost-free days, median 240NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 5,559 documented federal contamination records across its 2 counties, 3,630 of them in St. Louis County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 49% Alfisols, topsoil pH 5.1–6.6, area-weighted across its one mapped countyUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 7afrom Missouri
What this page can’t tell you
- Which end of the 3-day range your ground sits at — 238 days at one extreme, 241 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore St. Louis Metro
State growing guides
Counties in this region
Other growing regions across Missouri
The flat, deep, dark alluvial bottomland of the lower Mississippi River — extraordinarily fertile cotton, soybean, rice, and sweet-potato ground.
A rugged Interior Highlands of cherty, rocky soils, oak-hickory forest, and clear streams — brambles, peaches, and tough hill gardens.
The cold, short-season top of Missouri. This northern glaciated tier holds all five of the state's only USDA zone 5b counties, with frost-free windows of roughly 202-208 days — a full hardiness zone and several planting weeks shorter than central Missouri or the Bootheel. Rolling glacial till and claypan prairie soils, later spring frosts (last frost mid-April), and earlier fall frosts (first frost late October) mean a firmly northern planting calendar built around cold-hardy varieties — not an Ozark one.
Missouri's warmest, longest-season corner — the flat Mississippi Alluvial Plain south of the Ozark escarpment, where USDA zone 7a-7b and up to 258 frost-free days run a full 1.5-2 zones ahead of the rocky uplands 100 miles north. On these deep, drained delta soils growers keep a Delta calendar, not a Missouri one: cotton, rice, soybeans, and melons, with a spring that opens 3-4 weeks earlier than the rest of the state.