The Red River Valley spans USDA hardiness zones 3b-4b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
The flat floor of glacial Lake Agassiz along the Red River of the North — deep, dark lakebed clays and one of the coldest, shortest northern seasons on the platform (USDA zones 3b-4b) behind classic sugar-beet, potato, and spring-wheat country. On paper, tomato, red pine, sunflower, and potato all suit these conditions — on the ground, soil, sun, and drainage make the final call.
The Red River Valley spans Minnesota and North Dakota.
Your yard isn't all of the Red River Valley.
The Red River Valley spans USDA zones 3b-4b, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Red River Valley — soil, climate, flood, and parcel records. How we handle your address.
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The Red River Valley — the short answer
The Red River Valley: USDA zones 3b-4b, 149–173 frost-free days, across 2 states.
- USDA zones
- 3b-4b
- USDA PHZM 2023, aggregated over the footprint
- Frost-free season
- 149–173 days
- NOAA Regional Climate Centers ACIS, 1991-2020
- Counties
- 16
- US Census TIGER/Line 2025
- Region type
- County cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. Where a region publishes no measured season, no season figure is shown.
Hardiness Zone Range
What Grows in the Red River Valley
Plants matched to the Red River Valley's USDA zones 3b-4b, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the Red River Valley
Plants the USDA PLANTS Database documents as native and present in all 2 states this region crosses, kept only where the published hardiness range meets the Red River Valley’s USDA zones 3b-4b — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across the Red River Valley
The USDA soil survey maps this ground county by county. These are those records weighted by land area across 16 member counties — this region’s own profile, not a state figure.
The ground is predominantly Mollisols, at 71% of mapped acres, followed by Vertisols (17%), Entisols (5%) and Histosols (3%). Six soil orders appear somewhere inside the footprint, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Fargo, Bearden, and Glyndon.
36% of those acres are poorly drained, and another 30% somewhat poorly drained, 15% moderately well drained. Topsoil pH runs 6.7–7.9 between the lowest and the highest county on record. 31% of the footprint is classed prime farmland.
Soil order
Mollisols
Drainage
Poorly drained
Topsoil pH
6.7–7.9
Hydric soils
48%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Roseau County holds the most wetland ground here, at 78% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Red River Valley
The soil survey reads this ground county by county, and the readings above are those records summed across the Red River Valley. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records36% of the mapped acres across the Red River Valley are poorly drained — ground that sheds water slowly. That is area-weighted across all 16 of its mapped counties.
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
From county recordsTopsoil across the Red River Valley runs pH 6.7–7.9 — alkaline in eleven of its 16 counties.
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
Safe to Grow Here?
What the federal record shows across the Red River Valley — and how to grow with it.
Across the Red River Valley's 16 counties the federal record holds 4,831 documented sites, mostly Nitrate (2,238), Underground Storage Tanks (1,468) and Brownfields (977). The heaviest single county is Cass County, with 1,015.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to the Red River Valley to see which records sit where you actually grow.
Sources Checked
Summed across the 16 counties in the Red River Valley
A note from Gnorman
What an experienced grower watches for around here
In and around the Red River Valley, Nitrate runs higher than the national average — 2,238 sites across the 16 counties in the Red River Valley. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around 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).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Red River Valley
Everything above resolves to the Red River Valley as a whole — a footprint spanning USDA zones 3b-4b. Your parcel sits in exactly one of them. 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 region 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 regional average.
Your Lot vs the Red River Valley Average
Red River Valley Average
- ●USDA Zones 3b-4b, averaged across Red River Valley
- ●One soil character for all of Red River Valley
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Red River Valley's 3b-4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Red River Valley
Pull a site-specific report for your exact address in the Red River Valley — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Red River Valley averages can't show:
We read public map data around The Red River Valley — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Red River Valley average
How we know this about the Red River Valley
The boundary: a cluster of neighboring counties. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the Red River Valley
What hardiness zone is the Red River Valley?
The Red River Valley spans USDA hardiness zones 3b-4b, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the Red River Valley?
Measured between 28°F hard freezes, the Red River Valley's counties mostly run 161 to 167 frost-free days, median 163 (NOAA Regional Climate Centers ACIS, 1991–2020, over 16 member counties). That 6-day spread is the honest read — no single season describes 16 counties, and each county guide below carries its own.
When does frost risk end in the Red River Valley?
Across the Red River Valley, the middle half of member counties see their last 28°F hard freeze between Apr 28 and May 2 (median Apr 29), and their first fall freeze between Oct 8 and Oct 11. Those are hard freezes, not the last light frost: tender transplants wait for about May 20, and elevation decides which end of a 4-day spread you garden in.
What grows well in the Red River Valley?
The Red River Valley's conditions suit plants such as Tomato, Red Pine, Sunflower, Potato, Rhubarb, Honeycrisp Apple. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the Red River Valley defined?
The Red River Valley is defined here as a curated cluster of 16 neighboring counties that share a growing character. Growing regions have no official boundary, so this footprint is our published one — every county in it is named on this page.
Which states does the Red River Valley cover?
The Red River Valley spans Minnesota and North Dakota. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Driftless Area, The North Dakota Badlands, Twin Cities Metro, North Shore (Lake Superior), and Turtle Mountains share at least one state with the Red River Valley. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the Red River Valley’s own scale
6 of the readings below were taken at the Red River Valley's own scale — the zone 3b-4b band across its footprint, a median 163-day season across its 16 counties and 4,831 documented federal contamination records across its 16 counties, 1,015 of them in Cass County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 3b-4b aggregated across all 16 counties in the footprintUSDA PHZM 2023
- The boundary itself — the 16 counties this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 16 counties run 161 to 167 frost-free days, median 163NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 4,831 documented federal contamination records across its 16 counties, 1,015 of them in Cass County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 71% Mollisols, topsoil pH 6.7–7.9, area-weighted across its 16 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — all 2 member states' curated sets, merged and filtered to zones 3b-4bfrom Minnesota and North Dakota
What this page can’t tell you
- Which end of the 6-day range your ground sits at — 161 days at one extreme, 167 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the Red River Valley
State growing guides
Counties in this region
Other growing regions across Minnesota and North Dakota
An unglaciated landscape of steep ridges, deep valleys, and spring-fed coulees in the Upper Midwest — a stronghold of diversified small farms and cold-hardy fruit.
North Dakota's dry, wind-swept western half — the semi-arid side of the state's ~100th-meridian rainfall divide, where growers see roughly 6 to 8 inches less rain a year than the Red River Valley to the east. Zones run 4a-4b like much of the state, so the real work here isn't winter cold so much as drought: buttes-and-badlands terrain, hard prairie wind, and short-season dryland crops that need cover to hold moisture and finish before an early frost.
One metro, two frost calendars. The Minneapolis-St. Paul urban core sits in zone 5a while its outer suburbs and exurbs — Anoka, Carver, and Scott — drop to 4b, a real half-zone spread that stretches the frost-free season by more than two weeks across the seven counties (roughly 181 days in the exurbs to 199 in the city). Which side of that line your parcel falls on matters more here than any statewide answer.
Superior's deep water squeezes a 4a-4b shoreline band out of Duluth-to-Grand-Marais country whose interior reads 3b — later falls, safer springs, and the moderated edge that makes North Shore orchards and gardens possible.
The Turtle Mountains rise 300-400 feet above the surrounding drift prairie as a forested "island in a grassland sea" — an aspen-and-oak upland straddling the northern edges of Bottineau and Rolette counties that holds roughly 17% of North Dakota's native forest. That elevation, its lakes, and its cold-air pockets make it the coldest, shortest-season corner of the state: frost-free about 141 days at Bottineau and 145 at Rolette (both zone 3b), against a ~156-day North Dakota norm. Plan for a genuinely short, cool season here — it's the terrain, not the zone number, that sets this pocket apart from the rest of the northern border.