Knife River, Minnesota, sits in USDA hardiness zones 4a-5b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
On paper, honeycrisp apple, wild rice, tomato, and red pine all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in Knife River, 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 Knife River lot. 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.
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Quick Facts
USDA Zones
4a-5b
Last Hard Freeze (28°F)
Apr 27
Town normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Oct 28
Town normal — light frosts arrive a few weeks earlier
Town Area
426 acres
Hardiness Zone Range
Zone maps are averages across Knife River. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil varies lot by lot — soil types explained.
What Grows in Knife River
Plants matched to Knife River's USDA zones 4a-5b — each links to its full growing profile.
Is it too late to plant in Knife River?
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 30; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 28 — 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.
Growing Challenges in Minnesota
What an experienced grower plans around here — each one has a move.
Extreme cold (zone 3a: -40F) limits many species
Plant to zone 3 realities and the garden thrives — the hardy-plant palette here is deeper than most catalogs suggest.
Short growing season (100-140 frost-free days)
Start transplants indoors and add a cold frame — the standard Minnesota moves that stretch a short season into a full one.
Heavy clay soils in the Red River Valley
Valley clay grows world-class crops once drainage is handled — raised beds do it instantly, compost does it permanently.
For cultivar selection, pest pressure, and planting-time guidance specific to Minnesota, the University of Minnesota Extension is the authoritative local source.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Sources Checked
within ~10 miles of Knife River
Severity Distribution
within ~10 miles of Knife River
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Knife River, Brownfields runs higher than the national average — 67 sites nearby. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Check your specific parcel in Knife River
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
Knife River Average
- ●USDA Zones 4a-5b
- ●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 specific parcel in Knife River
Pull a site-specific report for your exact address in Knife River, Minnesota — 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 Knife River, Minnesota
- USDA Hardiness Zones: 4a-5b (USDA PHZM 2023)
- Last Hard Freeze (28°F): Apr 27 (town normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Oct 28 (town normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~184 (town normal, NOAA 1991–2020 Climate Normals)
- Land Area: 426 acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. Boundaries: US Census TIGER/Line 2025.
Frequently Asked Questions
What hardiness zone is Knife River, Minnesota?
Knife River sits in USDA hardiness zones 4a-5b, 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 Knife River?
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 30; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 28 — 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.
When does frost risk typically end in Knife River?
The last hard freeze (28°F) in Knife River typically lands around Apr 27, 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.
When is the first frost in Knife River?
The first hard freeze (28°F) in Knife River typically arrives around Oct 28, per NOAA 1991–2020 climate normals — the point most tender summer crops finish. Lighter frosts usually reach a couple of weeks earlier, so watch the forecast from late summer on and harvest or cover tender plants before the first cold night.
What vegetables grow in Knife River?
Knife River's zones 4a-5b support a wide range — strong performers include Honeycrisp Apple, Wild Rice, Tomato, and Red Pine. 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 Knife River, really?
Officially, Knife River sits in USDA zones 4a-5b (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 Knife River?
The federal record around Knife River is a meaningful one — 115 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.
How do I protect my plants from frost in Knife River?
As the season closes around the first 28°F hard freeze near Oct 28 (NOAA 1991–2020 climate normals), a few moves buy time: cover tender plants with floating row cover or an old sheet on still, clear nights, water the soil the afternoon before a freeze so it holds warmth overnight, and harvest frost-tender crops like tomatoes, peppers, and basil before the first hard night. Hardy greens and root crops shrug off light frost and often sweeten after it, so leave them in.
Everything on this page is a Knife River 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.