Grand Forks County, in North Dakota, sits in USDA hardiness zone 4a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Among the crops suited to this profile: cabbage, cranberry, turkish rocket, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Grand Forks County lies within the Red River Valley — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Grand Forks County holds more than one microclimate.
Soils and elevations shift across Grand Forks County, so your frost dates and drainage aren't the county average. 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 Grand Forks County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Grand Forks County — the short answer
Grand Forks County, North Dakota: USDA zone 4a, about 161 days between hard freezes, across 919K acres.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 1
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 9
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~161
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 919K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 Grand Forks County's average, not your lot's — a low corner or a tree line moves it. Against Grand Forks County's 161-day season, see what your own ground reads.
Heat in Grand Forks County
Across a year, Grand Forks County accumulates about 1,948 growing degree days above 50°F, about 35 more than the middle North Dakota county — ahead of 35 of North Dakota’s 53 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Grand Forks County
Across Grand Forks County, the ground is predominantly Mollisols, where Bearden, Antler, and Glyndon are the most extensive named soil series. The soil is generally somewhat poorly drained with a silty clay loam surface. Topsoil pH runs about 7.2–7.9, slightly alkaline. Rainfall drains through hydrologic group C soils.
Soil order
Mollisols
Drainage
Somewhat poorly drained
Prime farmland
43%
Hydric soils
18%
Soil still varies lot by lot — soil types explained.
How the ground varies across Grand Forks County
The USDA soil survey maps 51% of Grand Forks County as somewhat poorly drained — but another 47% drains differently: 19% moderately well drained, 12% well drained.
Bearden is the most extensive named soil at 22% of mapped acres, then Antler (9%) and Glyndon (6%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Grand Forks County
Each reading below is measured for Grand Forks County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Grand Forks County are somewhat poorly drained, in hydrologic group C — ground that sheds water slowly.
Beds can stay saturated for days after heavy rain, and the roots of most vegetables, berries, and fruit trees suffocate or rot in soil that never drains.
Raised beds or mounded rows lift roots above the wet zone; choose water-tolerant crops for the lowest spots.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Grand Forks County runs about pH 7.2–7.9, on the alkaline side.
Many vegetables cope, but acid-lovers like blueberries struggle, and iron and manganese lock up above about pH 7.5 — leaves yellow between the veins even in rich soil.
Elemental sulfur and generous organic matter lower pH slowly for the beds that need it; test first so you add only what the soil actually calls for.
USDA NRCS SSURGO
Season length
MeasuredGrand Forks County runs about 161 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredGrand Forks County 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 Grand Forks County is in
Grand Forks County spans 2 EPA Level III ecoregions — Lake Agassiz Plain (81%) and Northern Glaciated Plains (19%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Grand Forks County
We scored all 1,086 plants against Grand Forks County's own USDA zone 4a and its own 161-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's North Dakota profile.
Is it too late to plant in Grand Forks County?
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 3; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 1 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 9 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
Documented around Grand Forks County
- monarch butterfly62 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Grand Forks County
USGS estimates 630,405 lb of Glyphosate on Grand Forks County farmland in 2019, its largest by weight, ahead of Bentazone (95,806 lb) and Metolachlor & Metolachlor-s (90,875 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Grand Forks County — and how to grow with it.
We checked the federal record across Grand Forks County — 521 documented sites across 6 of the 9 source types we track.
The most significant on record: 2 Superfund sites (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Grand Forks County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Grand Forks County
Closest first, across Grand Forks County. Listing isn't leaking, and distance isn't exposure.
- GENERAL ATOMICS AERONAUTICAL SYSTEMS - GRAND FORKS FLIGHT TEST & TRAINING FACILIBrownfields · 2.0 mi
- NORTHROP GRUMMAN SYSTEMS CORPORATION - EMERADOBrownfields · 2.0 mi
- Strata Arvilla Gravel PitUnderground Storage Tanks · 2.3 mi
- 152-054-36DACNitrate · 2.3 mi
- ND Parks and Tourism DeptUnderground Storage Tanks · 2.7 mi
- 151-053-01CCCNitrate · 3.1 mi
- Sand Steel Building Co.Underground Storage Tanks · 3.7 mi
- 151-053-01DCDNitrate · 3.7 mi
- Emerado SchoolsUnderground Storage Tanks · 3.8 mi
- 151-054-24BBBNitrate · 3.9 mi
- Nodak Rural Electric Coop IncUnderground Storage Tanks · 4.0 mi
- Superpumper 6Underground Storage Tanks · 4.0 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Grand Forks County'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 Grand Forks County.
Total Sites
521
across Grand Forks County
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
across Grand Forks County
Severity Distribution
across Grand Forks County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Grand Forks County, Nitrate runs higher than the national average — 204 sites across Grand Forks County. 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 Grand Forks County
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 Grand Forks County average
Your land is one point inside Grand Forks County
Everything above resolves to Grand Forks County as a whole — one PHZM band and one county frost record, read across 919K 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 county 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 county average.
Your Lot vs the Grand Forks County Average
Grand Forks County Average
- ●USDA Zones 4a, averaged across Grand Forks County
- ●One soil character for all of Grand Forks County
- ●Frost dates read at Grand Forks County's scale: May 1 to Oct 9
YOUR Parcel
- ✓Your exact zone, not Grand Forks County's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Grand Forks County
Pull a site-specific report for your exact address in Grand Forks County, North Dakota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Grand Forks County averages can't show:
We read public map data around Grand Forks County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Grand Forks County average
How we know this about Grand Forks County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Grand Forks County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Grand Forks County
When does frost risk typically end in Grand Forks County?
The last hard freeze (28°F) in Grand Forks County typically lands around May 1, 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 22.
How long is the growing season in Grand Forks County?
Measured between 28°F hard freezes, Grand Forks County sees about 161 frost-free days — roughly May 1 through Oct 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 22 to Sep 25, about 126 days.
Is the soil safe to grow vegetables in Grand Forks County?
The federal record around Grand Forks County is a meaningful one — 521 documented sites, mostly Nitrate entries (204), the nearest Brownfields record about 2.0 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
Everything above is measured at Grand Forks County's scale — its 4a band and its 161-day season. Your yard writes its own version of Grand Forks County's numbers: 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 North Dakota's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Grand Forks County’s own scale
9 of the readings below were taken at Grand Forks County's own scale — its own ~161-day span between 28°F freezes, the 3 most extensive soil series mapped here and 521 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Grand Forks County's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Grand Forks County's own 28°F hard-freeze dates and its ~161-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Grand Forks CountyUSDA NRCS SSURGO
- 521 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Brownfields record about 2.0 miles outFederal environmental registers
- Grand Forks County's boundary and the 919,177 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~161-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Grand Forks County spans, Lake Agassiz Plain the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Grand Forks County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Grand Forks County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every North Dakota grower plans around — written at state scale, so they stay on the state guidefrom North Dakota
What this page can’t tell you
- How the season shifts across Grand Forks County — the ~161 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Grand Forks County's 919,177 acreswhy one lot differs from the next →
- Which of those 521 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Grand Forks Countyread your own land →