Marmarth, North Dakota, sits in USDA hardiness zone 4a — a zone band wide enough that plant choice, not possibility, is the interesting question.
A short list that earns its place here — cabbage, cranberry, cilantro, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Marmarth, 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 Marmarth 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 Marmarth — soil, climate, flood, and parcel records. How we handle your address.
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Marmarth — the short answer
Marmarth, North Dakota: USDA zone 4a, about 146 days between hard freezes, across 2K acres of city.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 30
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~146
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 2K 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 4a is Marmarth's average, not your lot's — a low corner or a tree line moves it. Against Marmarth's 146-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Marmarth
Each reading below is measured for Marmarth itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredMarmarth runs about 146 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
MeasuredMarmarth sits in USDA hardiness zone 4a.
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 Marmarth is in
Marmarth sits in the Northwestern Great Plains — EPA Level III, inside the wider Great Plains. That is read at Marmarth's own centroid rather than borrowed from Slope County.
What Grows in Marmarth
Every plant below cleared Marmarth's own zone 4a and its 146-day season. Each card opens that plant's North Dakota profile. How we score.
Is it too late to plant in Marmarth?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Apr 9; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 7 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 30 — long-season crops need about 90 days of runway, quick greens only 30. In a season this compact, fast finishers and cold-hardy greens do the late work, and garlic tucked in before the freeze repays you next summer.
What's on the federal record near Marmarth
Closest first, within ~10 miles of Marmarth. Listing isn't leaking, and distance isn't exposure.
- 133-105-30CCCNitrate · 0.5 mi
- Burlington Northern Railroad CompanyUnderground Storage Tanks · 0.6 mi
- Duffys CornerUnderground Storage Tanks · 0.7 mi
- 133-106-34AAANitrate · 1.9 mi
- 133-106-13ADB2Nitrate · 2.2 mi
- 132-105-08BBDNitrate · 4.6 mi
- 132-106-26BDCNitrate · 5.1 mi
- 132-105-16BDBNitrate · 6.1 mi
- 134-106-27DBDNitrate · 6.1 mi
- 131-106-03DAANitrate · 7.1 mi
- 131-106-04DCCNitrate · 7.4 mi
- 134-105-26BAANitrate · 8.0 mi
3 more sites are on the record inside the same radius. See them on the map
Measured from Marmarth'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 Marmarth.
Severity Distribution
within ~10 miles of Marmarth
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Marmarth, Nitrate runs higher than the national average — 26 sites within ~10 miles of Marmarth. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Marmarth
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 Marmarth average
Your land is one point inside Marmarth
Everything above resolves to Marmarth as a whole — one PHZM band and one 28°F frost record, read across 2K 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 Marmarth Average
Marmarth Average
- ●USDA Zones 4a, averaged across Marmarth
- ●One soil character for all of Marmarth
- ●Frost dates read at Marmarth's scale: May 7 to Sep 30
YOUR Parcel
- ✓Your exact zone, not Marmarth's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Marmarth
Pull a site-specific report for your exact address in Marmarth, North Dakota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Marmarth averages can't show:
We read public map data around Marmarth — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Marmarth average
How we know this about Marmarth
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 Marmarth’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 Marmarth
When does frost risk typically end in Marmarth?
The last hard freeze (28°F) in Marmarth typically lands around May 7, 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 May 28.
When is the first frost in Marmarth?
The first hard freeze (28°F) in Marmarth typically arrives around Sep 30, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 16, so the watching starts about Aug 31 — about 146 days after the spring freeze cleared.
How long is the growing season in Marmarth?
Measured between 28°F hard freezes, Marmarth sees about 146 frost-free days — roughly May 7 through Sep 30, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 28 to Sep 16, about 111 days.
Is the soil safe to grow vegetables in Marmarth?
The federal record around Marmarth is light — 28 documented sites across the 9 federal source types we checked, mostly Nitrate entries (26), the nearest Nitrate record about 0.5 miles out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do gardeners stretch the season in Marmarth?
With about 146 frost-free days between hard freezes, Marmarth 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 174 to 202 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 7 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Marmarth's scale — its 4a band and its 146-day season. Your yard writes its own version of Marmarth'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 Marmarth’s own scale
6 of the readings below were taken at Marmarth's own scale — its own ~146-day season between 28°F freezes, the 1,650 acres it covers and 28 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Marmarth's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Marmarth's own 28°F hard-freeze dates, about May 7 and Sep 30 and the ~146-day span between themNOAA 1991–2020 Climate Normals
- 28 documented contamination sites on the federal record near Marmarth, the closest Nitrate record about 0.5 miles out from the town centreFederal environmental registers
- Marmarth's boundary and the 1,650 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~146-day seasonGrowable Ground crop-matching engine
- The ecoregion at Marmarth's own centroid, the Northwestern Great PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Marmarth's 1,650 acres read through its county's SSURGO summaryfrom Slope County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Slope County
- The growing challenges every North Dakota grower plans around — written at state scale, so they stay on the state guidefrom North Dakota
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Slope County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Marmarth's 1,650 acreswhy one lot differs from the next →
- Which side of Marmarth you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,650 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 0.5 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 Marmarth-wide figureread your own land →
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