Union, Missouri, sits in USDA hardiness zone 6b — a zone band wide enough that plant choice, not possibility, is the interesting question.
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 Union, 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 Union 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 Union — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Union — the short answer
Union, Missouri: USDA zone 6b, about 215 days between hard freezes, across 6K acres of city.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 30
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 31
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~215
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 6K 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 Union's average, not your lot's — a low corner or a tree line moves it. Against Union's 215-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Union
Each reading below is measured for Union itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredUnion runs about 215 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
MeasuredUnion 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 Union is in
Union sits in the Ozark Highlands — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Union's own centroid rather than borrowed from Franklin County.
What Grows in Union
Every plant below cleared Union's own zone 6b and its 215-day season. Each card opens that plant's Missouri profile. How we score.
Is it too late to plant in Union?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Mar 2; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 30 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 31 — 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 Union
Survey cells within 31 miles of Union checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 275 miles off. What to watch for.
What's on the federal record near Union
Closest first, within ~10 miles of Union. Listing isn't leaking, and distance isn't exposure.
- MPC 81Underground Storage Tanks · 1400 ft
- QUIKTRIP #672Underground Storage Tanks · 1900 ft
- WALGREENS #9692Brownfields · 2400 ft
- WEST 50 CITGOUnderground Storage Tanks · 2600 ft
- BROWN SHOE COToxics Release Inventory · 0.5 mi
- PETRO MART UNIONUnderground Storage Tanks · 0.5 mi
- UNION SPECIAL ROAD DIST #1Underground Storage Tanks · 0.6 mi
- PURSCHKE OIL CO INCUnderground Storage Tanks · 0.6 mi
- CITY OF UNIONUnderground Storage Tanks · 0.6 mi
- PRO BODY WORKS INCBrownfields · 0.7 mi
- UNION MOTO MARTUnderground Storage Tanks · 0.7 mi
- IRENE SUDHOLTUnderground Storage Tanks · 0.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Union'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 Union.
Sources Checked
within ~10 miles of Union
Severity Distribution
within ~10 miles of Union
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Union, two things run higher than the national average within ~10 miles of Union — Mining (38 sites) and Toxics Release Inventory (42 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Union
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 Union average
Your land is one point inside Union
Everything above resolves to Union as a whole — one PHZM band and one 28°F frost record, read across 6K 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 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 Union Average
Union Average
- ●USDA Zones 6b, averaged across Union
- ●One soil character for all of Union
- ●Frost dates read at Union's scale: Mar 30 to Oct 31
YOUR Parcel
- ✓Your exact zone, not Union's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Union
Pull a site-specific report for your exact address in Union, Missouri — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Union averages can't show:
We read public map data around Union — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Union average
How we know this about Union
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 Union’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 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 Union
When does frost risk typically end in Union?
The last hard freeze (28°F) in Union typically lands around Mar 30, 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 20.
When is the first frost in Union?
The first hard freeze (28°F) in Union typically arrives around Oct 31, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 17, so the watching starts about Oct 1 — about 215 days after the spring freeze cleared.
How long is the growing season in Union?
Measured between 28°F hard freezes, Union sees about 215 frost-free days — roughly Mar 30 through Oct 31, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 20 to Oct 17, about 180 days.
Is the soil safe to grow vegetables in Union?
The federal record around Union runs heavier than most — 331 documented sites, mostly Underground Storage Tanks entries (140), the nearest Underground Storage Tanks record about 0.3 miles out — 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.
How do I protect my plants from frost in Union?
From about Oct 1 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 Oct 31 (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 Oct 31. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Union's scale — its 6b band and its 215-day season. Your yard writes its own version of Union'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 Union’s own scale
7 of the readings below were taken at Union's own scale — its own ~215-day season between 28°F freezes, the 5,819 acres it covers and 331 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Union's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Union's own 28°F hard-freeze dates, about Mar 30 and Oct 31 and the ~215-day span between themNOAA 1991–2020 Climate Normals
- 331 documented contamination sites on the federal record near Union, the closest Underground Storage Tanks record about 0.3 miles out from the town centreFederal environmental registers
- Union's boundary and the 5,819 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~215-day seasonGrowable Ground crop-matching engine
- The ecoregion at Union's own centroid, the Ozark HighlandsUS EPA Level III Ecoregions
- Lanternfly survey cells around Union 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 Union's 5,819 acres read through its county's SSURGO summaryfrom Franklin County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Franklin 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 Franklin County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Union's 5,819 acreswhy one lot differs from the next →
- Which side of Union you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 5,819 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.3 miles 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 Union-wide figureread your own land →
More in Missouri
Growing region
Nearby growing guides