Ambrose, North Dakota, sits in USDA hardiness zone 3b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Growers here do well with cabbage, cranberry, epazote, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Ambrose, 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 Ambrose 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 Ambrose — soil, climate, flood, and parcel records. How we handle your address.
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Ambrose — the short answer
Ambrose, North Dakota: USDA zone 3b, about 147 days between hard freezes, across 646 acres of city.
- USDA zone
- 3b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 1
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~147
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 646 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 3b is Ambrose's average, not your lot's — a low corner or a tree line moves it. Against Ambrose's 147-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Ambrose
Each reading below is measured for Ambrose itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredAmbrose runs about 147 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
MeasuredAmbrose sits in USDA hardiness zone 3b.
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 Ambrose is in
Ambrose sits in the Northern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Ambrose's own centroid, and it is not what its county reads: Divide County is mostly Northwestern Glaciated Plains. The wider page above you is answering a different question about different ground.
What Grows in Ambrose
Every plant below cleared Ambrose's own zone 3b and its 147-day season. Each card opens that plant's North Dakota profile. How we score.
Is it too late to plant in Ambrose?
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 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 Oct 1 — 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 Ambrose
Closest first, within ~10 miles of Ambrose. Listing isn't leaking, and distance isn't exposure.
- 163-099-12CCA1Nitrate · 200 ft
- 163-099-12CCA2Nitrate · 200 ft
- 163-099-11CDDNitrate · 0.8 mi
- 163-098-18CDC1Nitrate · 1.6 mi
- 163-099-10BBANitrate · 2.2 mi
- 163-099-22DABNitrate · 2.2 mi
- 163-098-17AABNitrate · 2.6 mi
- US West CommunicationsUnderground Storage Tanks · 3.2 mi
- 163-099-35BCBNitrate · 3.6 mi
- 163-099-18AAANitrate · 4.3 mi
- 163-098-22BAANitrate · 4.4 mi
- 163-098-27CDDNitrate · 5.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Ambrose'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 Ambrose.
Total Sites
72
within ~10 miles of Ambrose
Risk Level
Moderate
Highest-severity
58 nitrate monitoring sites
Severity Distribution
within ~10 miles of Ambrose
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Ambrose, Nitrate runs higher than the national average — 58 sites within ~10 miles of Ambrose. That's not a problem with your land — it's information about it.
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 Ambrose
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 Ambrose average
Your land is one point inside Ambrose
Everything above resolves to Ambrose as a whole — one PHZM band and one 28°F frost record, read across 646 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 Ambrose Average
Ambrose Average
- ●USDA Zones 3b, averaged across Ambrose
- ●One soil character for all of Ambrose
- ●Frost dates read at Ambrose's scale: May 7 to Oct 1
YOUR Parcel
- ✓Your exact zone, not Ambrose's 3b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Ambrose
Pull a site-specific report for your exact address in Ambrose, North Dakota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Ambrose averages can't show:
We read public map data around Ambrose — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Ambrose average
How we know this about Ambrose
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 Ambrose’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 Ambrose
When does frost risk typically end in Ambrose?
The last hard freeze (28°F) in Ambrose 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 Ambrose?
The first hard freeze (28°F) in Ambrose typically arrives around Oct 1, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 17, so the watching starts about Sep 1 — about 147 days after the spring freeze cleared.
How long is the growing season in Ambrose?
Measured between 28°F hard freezes, Ambrose sees about 147 frost-free days — roughly May 7 through Oct 1, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 28 to Sep 17, about 112 days.
Is the soil safe to grow vegetables in Ambrose?
The federal record around Ambrose shows 72 documented sites, mostly Nitrate entries (58), the nearest Nitrate record under a tenth of a mile out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do gardeners stretch the season in Ambrose?
With about 147 frost-free days between hard freezes, Ambrose 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 175 to 203 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 Ambrose's scale — its 3b band and its 147-day season. Your yard writes its own version of Ambrose'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 Ambrose’s own scale
6 of the readings below were taken at Ambrose's own scale — its own ~147-day season between 28°F freezes, the 646 acres it covers and 72 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Ambrose's own USDA hardiness band, zones 3bUSDA PHZM 2023
- Ambrose's own 28°F hard-freeze dates, about May 7 and Oct 1 and the ~147-day span between themNOAA 1991–2020 Climate Normals
- 72 documented contamination sites on the federal record near Ambrose, the closest Nitrate record under a tenth of a mile out from the town centreFederal environmental registers
- Ambrose's boundary and the 646 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 3b and a ~147-day seasonGrowable Ground crop-matching engine
- Ambrose sits in the Northern Glaciated Plains — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Ambrose's 646 acres read through its county's SSURGO summaryfrom Divide County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Divide 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 Divide County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Ambrose's 646 acreswhy one lot differs from the next →
- Which side of Ambrose you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 646 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record under a tenth of a mile 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 Ambrose-wide figureread your own land →
More in North Dakota
Wider growing context
What grows across North DakotaAmbrose sits outside our named growing regions, so North Dakota as a whole is its closest context here.