St. Louis County, in Missouri, sits in USDA hardiness zone 7a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
On paper, tomato, peach, grape, and dogwood all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
St. Louis County holds more than one microclimate.
Soils and elevations shift across St. Louis County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Quick Facts
USDA Zones
7a
Last Hard Freeze (28°F)
Mar 5
County normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Nov 30
County normal — light frosts arrive a few weeks earlier
County Area
325K acres
Hardiness Zone Range
Zone maps are averages across St. Louis County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in St. Louis County
Across St. Louis County, the ground is predominantly Alfisols, where Harvester, Menfro, and Winfield are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 5.1–6.6, moderately acidic. Rainfall drains through hydrologic group C soils.
Soil order
Alfisols
Drainage
Well drained
Prime farmland
7%
Hydric soils
7%
Soil still varies lot by lot — soil types explained.
What Grows in St. Louis County
Plants matched to St. Louis County's USDA zones 7a — each links to its full growing profile.
Is it too late to plant in St. Louis County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Feb 5; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 5 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 30 — 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.
Growing Challenges in Missouri
What an experienced grower plans around here — each one has a move.
Highly variable weather with late frosts and early heat
Let your local frost normals call the plantings — Missouri springs punish the calendar-planters and reward the patient.
Heavy clay soils in many regions
Raised beds solve clay drainage the first weekend — and yearly compost turns the ground under them into loam.
Ozark soils are thin and rocky
One soil test shows what thin Ozark ground actually holds — then build up with compost or beds where the depth runs out.
For cultivar selection, pest pressure, and planting-time guidance specific to Missouri, the MU Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across St. Louis County — and how to grow with it.
We checked the federal record across St. Louis County — 3,630 documented sites across 6 of the 9 source types we track.
The most significant on record: 35 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
St. Louis County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Sources Checked
across St. Louis County
Severity Distribution
across St. Louis County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around St. Louis County, Toxic Release Inventory runs higher than the national average — 232 sites nearby. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Toxic 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.
Check your specific parcel in St. Louis County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
St. Louis County Average
- ●USDA Zones 7a
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in St. Louis County
Pull a site-specific report for your exact address in St. Louis County, Missouri — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for St. Louis County, Missouri
- USDA Hardiness Zones: 7a (USDA PHZM 2023)
- Last Hard Freeze (28°F): Mar 5 (county normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Nov 30 (county normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~270 (county normal, NOAA 1991–2020 Climate Normals)
- County Land Area: 325K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the St. Louis County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is St. Louis County, Missouri?
St. Louis County sits in USDA hardiness zone 7a, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
Is it too late to plant in St. Louis County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Feb 5; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 5 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 30 — 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.
When does frost risk typically end in St. Louis County?
The last hard freeze (28°F) in St. Louis County typically lands around Mar 5, per NOAA 1991–2020 climate normals — an earlier marker than the light-frost dates many planting charts quote. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
How long is the growing season in St. Louis County?
Measured between 28°F hard freezes, St. Louis County sees about 270 frost-free days — roughly Mar 5 through Nov 30, per NOAA 1991–2020 climate normals. Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
What vegetables grow in St. Louis County?
St. Louis County's zone 7a supports a wide range — strong performers include Tomato, Peach, Grape, Dogwood, and Blackberry. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is St. Louis County, really?
Officially, St. Louis County sits in USDA zone 7a (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in St. Louis County?
The federal record around St. Louis County runs heavier than most — 3,630 documented sites — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
Just moved to St. Louis County — what should I know before planting?
Start with three facts. St. Louis County sits in USDA zone 7a, which sets what survives winter; the last 28°F hard freeze typically clears around Mar 5, with about 270 frost-free days to work with (NOAA 1991–2020 climate normals); and 3,630 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a St. Louis County average. Your yard writes its own version — 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 Missouri's frost window, season length, and soil profile against the plant's real requirements.