Sioux County, in North Dakota, sits in USDA hardiness zone 4b — a zone band wide enough that plant choice, not possibility, is the interesting question.
A short list that earns its place here — sunflower, potato, american elm, and rhubarb — with any one site's soil, sun, and drainage making the final cut.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Sioux County holds more than one microclimate.
Soils and elevations shift across Sioux County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Quick Facts
USDA Zones
4b
Last Hard Freeze (28°F)
Apr 24
County normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Oct 19
County normal — light frosts arrive a few weeks earlier
County Area
700K acres
Hardiness Zone Range
Zone maps are averages across Sioux County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Sioux County
Across Sioux County, the ground is predominantly Mollisols, where Vebar, Janesburg, and Regent are the most extensive named soil series. The soil is generally well drained with a fine sandy loam surface. Topsoil pH runs about 6.5–7.1, neutral. Rainfall drains through hydrologic group C soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
1%
Hydric soils
2%
Soil still varies lot by lot — soil types explained.
What Grows in Sioux County
Plants matched to Sioux County's USDA zones 4b — each links to its full growing profile.
Is it too late to plant in Sioux County?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Mar 27; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 24 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 19 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
Growing Challenges in North Dakota
What an experienced grower plans around here — each one has a move.
Extreme cold (-40F) and short growing season
Cold-proven varieties plus a high tunnel make North Dakota's short season dependable — northern growers' standard kit.
Persistent wind desiccates plants
A windbreak is the highest-return structure on the northern plains — even a snow fence changes what survives.
Low rainfall in western ND
Out west, drip irrigation and mulch decide the season — set the water system up front.
For cultivar selection, pest pressure, and planting-time guidance specific to North Dakota, the NDSU Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Sioux County — and how to grow with it.
We checked the federal record across Sioux County — 192 documented sites across 5 of the 9 source types we track.
The most significant on record: 1 Superfund site. 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 Sioux 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.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Sources Checked
across Sioux County
Severity Distribution
across Sioux County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Sioux County, Nitrate runs higher than the national average — 166 sites nearby. 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 Sioux County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Sioux County Average
- ●USDA Zones 4b
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Sioux County
Pull a site-specific report for your exact address in Sioux County, North Dakota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Sioux County, North Dakota
- USDA Hardiness Zones: 4b (USDA PHZM 2023)
- Last Hard Freeze (28°F): Apr 24 (county normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Oct 19 (county normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~178 (county normal, NOAA 1991–2020 Climate Normals)
- County Land Area: 700K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Sioux County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Sioux County, North Dakota?
Sioux County sits in USDA hardiness zone 4b, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
Is it too late to plant in Sioux County?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Mar 27; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 24 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 19 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
When does frost risk typically end in Sioux County?
The last hard freeze (28°F) in Sioux County typically lands around Apr 24, per NOAA 1991–2020 climate normals — an earlier marker than the light-frost dates many planting charts quote. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
How long is the growing season in Sioux County?
Measured between 28°F hard freezes, Sioux County sees about 178 frost-free days — roughly Apr 24 through Oct 19, per NOAA 1991–2020 climate normals. Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
What vegetables grow in Sioux County?
Sioux County's zone 4b supports a wide range — strong performers include Sunflower, Potato, American Elm, and Rhubarb. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Sioux County, really?
Officially, Sioux County sits in USDA zone 4b (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Sioux County?
The federal record around Sioux County is a meaningful one — 192 documented sites — 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.
Just moved to Sioux County — what should I know before planting?
Start with three facts. Sioux County sits in USDA zone 4b, which sets what survives winter; the last 28°F hard freeze typically clears around Apr 24, with about 178 frost-free days to work with (NOAA 1991–2020 climate normals); and 192 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Sioux County average. Your yard writes its own version — 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.