Jefferson City, Montana, sits in USDA hardiness zone 4b — 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, cranberry, cilantro, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Jefferson City, 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 Jefferson City 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 Jefferson City — soil, climate, flood, and parcel records. How we handle your address.
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Jefferson City — the short answer
Jefferson City, Montana: USDA zone 4b, about 139 days between hard freezes, across 15K acres of town.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 12
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 28
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~139
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 15K 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 4b is Jefferson City's average, not your lot's — a low corner or a tree line moves it. Against Jefferson City's 139-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Jefferson City
Each reading below is measured for Jefferson City itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredJefferson City runs about 139 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredJefferson City sits in USDA hardiness zone 4b.
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 Jefferson City is in
Jefferson City sits in the Middle Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Jefferson City's own centroid rather than borrowed from Jefferson County.
What Grows in Jefferson City
Every plant below cleared Jefferson City's own zone 4b and its 139-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Jefferson City?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Apr 14; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 12 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 28 — long-season crops need about 90 days of runway, quick greens only 30. Short seasons reward decisiveness — quick-maturing varieties late, hardy greens under cover, and next year’s garlic in the ground before it closes.
What's on the federal record near Jefferson City
Closest first, within ~10 miles of Jefferson City. Listing isn't leaking, and distance isn't exposure.
- JEFFERSON CITY STOREUnderground Storage Tanks · 0.8 mi
- 07N03W08CBCB01Nitrate · 0.8 mi
- Bo GulchMining · 0.9 mi
- Black RockMining · 1.2 mi
- ReddingsMining · 1.3 mi
- Silver Tip MineMining · 1.3 mi
- Silver TipMining · 1.3 mi
- 08N03W31CBDD01Nitrate · 1.3 mi
- Madison MineMining · 1.3 mi
- Big ChiefMining · 1.4 mi
- 07N03W08DCCD01Nitrate · 1.4 mi
- Big Chief Mine GolcondaMining · 1.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Jefferson City'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 Jefferson City.
Total Sites
423
within ~10 miles of Jefferson City
Risk Level
High
Highest-severity
7 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Jefferson City
Severity Distribution
within ~10 miles of Jefferson City
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Jefferson City, two things run higher than the national average within ~10 miles of Jefferson City — Mining (335 sites) and Superfund (7 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Jefferson City
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 Jefferson City average
Your land is one point inside Jefferson City
Everything above resolves to Jefferson City as a whole — one PHZM band and one 28°F frost record, read across 15K 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 Jefferson City Average
Jefferson City Average
- ●USDA Zones 4b, averaged across Jefferson City
- ●One soil character for all of Jefferson City
- ●Frost dates read at Jefferson City's scale: May 12 to Sep 28
YOUR Parcel
- ✓Your exact zone, not Jefferson City's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Jefferson City
Pull a site-specific report for your exact address in Jefferson City, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Jefferson City averages can't show:
We read public map data around Jefferson City — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Jefferson City average
How we know this about Jefferson City
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 Jefferson City’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 Jefferson City
When does frost risk typically end in Jefferson City?
The last hard freeze (28°F) in Jefferson City typically lands around May 12, 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 Jun 2.
When is the first frost in Jefferson City?
The first hard freeze (28°F) in Jefferson City typically arrives around Sep 28, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 14, so the watching starts about Aug 29 — about 139 days after the spring freeze cleared.
How long is the growing season in Jefferson City?
Measured between 28°F hard freezes, Jefferson City sees about 139 frost-free days — roughly May 12 through Sep 28, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 2 to Sep 14, about 104 days.
Is the soil safe to grow vegetables in Jefferson City?
The federal record around Jefferson City runs heavier than most — 423 documented sites, mostly Mining entries (335), the nearest Underground Storage Tanks record about 0.8 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 gardeners stretch the season in Jefferson City?
With about 139 frost-free days between hard freezes, Jefferson City rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 167 to 195 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 12 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Jefferson City's scale — its 4b band and its 139-day season. Your yard writes its own version of Jefferson City'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 Jefferson City’s own scale
6 of the readings below were taken at Jefferson City's own scale — its own ~139-day season between 28°F freezes, the 14,858 acres it covers and 423 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Jefferson City's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Jefferson City's own 28°F hard-freeze dates, about May 12 and Sep 28 and the ~139-day span between themNOAA 1991–2020 Climate Normals
- 423 documented contamination sites on the federal record near Jefferson City, the closest Underground Storage Tanks record about 0.8 miles out from the town centreFederal environmental registers
- Jefferson City's boundary and the 14,858 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~139-day seasonGrowable Ground crop-matching engine
- The ecoregion at Jefferson City's own centroid, the Middle RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Jefferson City's 14,858 acres read through its county's SSURGO summaryfrom Jefferson County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Jefferson County
- The growing challenges every Montana grower plans around — written at state scale, so they stay on the state guidefrom Montana
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Jefferson County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Jefferson City's 14,858 acreswhy one lot differs from the next →
- Which side of Jefferson City you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 14,858 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.8 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 Jefferson City-wide figureread your own land →
More in Montana
Wider growing context
What grows across MontanaJefferson City sits outside our named growing regions, so Montana as a whole is its closest context here.
Nearby growing guides