Riverdale, North Dakota, sits in USDA hardiness zone 4a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Expect cabbage, cranberry, turkish rocket, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Riverdale, 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 Riverdale 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 Riverdale — soil, climate, flood, and parcel records. How we handle your address.
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Riverdale — the short answer
Riverdale, North Dakota: USDA zone 4a, about 160 days between hard freezes, across 888 acres of city.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 1
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 8
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~160
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 888 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 4a is Riverdale's average, not your lot's — a low corner or a tree line moves it. Against Riverdale's 160-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Riverdale
Each reading below is measured for Riverdale itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRiverdale runs about 160 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
MeasuredRiverdale 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 Riverdale is in
Riverdale sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Riverdale's own centroid rather than borrowed from McLean County.
What Grows in Riverdale
Every plant below cleared Riverdale's own zone 4a and its 160-day season. Each card opens that plant's North Dakota profile. How we score.
Is it too late to plant in Riverdale?
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 8 — 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.
What's on the federal record near Riverdale
Closest first, within ~10 miles of Riverdale. Listing isn't leaking, and distance isn't exposure.
- The Honey HoleUnderground Storage Tanks · 1400 ft
- North Dakota Game and Fish DepartmentUnderground Storage Tanks · 2100 ft
- City of RiverdaleUnderground Storage Tanks · 2200 ft
- Riverdale Public SchoolUnderground Storage Tanks · 2300 ft
- Riverdale TownsiteUnderground Storage Tanks · 2300 ft
- US Army Corps of Engineers Maintenance FacilityUnderground Storage Tanks · 2300 ft
- UNDERWOOD BODY SHOPBrownfields · 2400 ft
- 147-084-34ADBNitrate · 1.1 mi
- 147-084-25CCCNitrate · 2.1 mi
- Garrison Dam National Fish HatcheryUnderground Storage Tanks · 2.2 mi
- Robinson Stock FarmUnderground Storage Tanks · 2.2 mi
- 146-084-08DBDNitrate · 2.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Riverdale'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 Riverdale.
Total Sites
73
within ~10 miles of Riverdale
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Riverdale
Severity Distribution
within ~10 miles of Riverdale
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Riverdale, Nitrate runs higher than the national average — 50 sites within ~10 miles of Riverdale. 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).
Check your specific parcel in Riverdale
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 Riverdale average
Your land is one point inside Riverdale
Everything above resolves to Riverdale as a whole — one PHZM band and one 28°F frost record, read across 888 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 Riverdale Average
Riverdale Average
- ●USDA Zones 4a, averaged across Riverdale
- ●One soil character for all of Riverdale
- ●Frost dates read at Riverdale's scale: May 1 to Oct 8
YOUR Parcel
- ✓Your exact zone, not Riverdale's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Riverdale
Pull a site-specific report for your exact address in Riverdale, North Dakota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Riverdale averages can't show:
We read public map data around Riverdale — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Riverdale average
How we know this about Riverdale
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 Riverdale’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 Riverdale
When does frost risk typically end in Riverdale?
The last hard freeze (28°F) in Riverdale 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.
When is the first frost in Riverdale?
The first hard freeze (28°F) in Riverdale typically arrives around Oct 8, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 24, so the watching starts about Sep 8 — about 160 days after the spring freeze cleared.
How long is the growing season in Riverdale?
Measured between 28°F hard freezes, Riverdale sees about 160 frost-free days — roughly May 1 through Oct 8, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 22 to Sep 24, about 125 days.
Is the soil safe to grow vegetables in Riverdale?
The federal record around Riverdale is a meaningful one — 73 documented sites, mostly Nitrate entries (50), the nearest Underground Storage Tanks record about 0.3 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.
How do I protect my plants from frost in Riverdale?
From about Sep 8 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Oct 8 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Oct 8. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Riverdale's scale — its 4a band and its 160-day season. Your yard writes its own version of Riverdale'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 Riverdale’s own scale
6 of the readings below were taken at Riverdale's own scale — its own ~160-day season between 28°F freezes, the 888 acres it covers and 73 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Riverdale's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Riverdale's own 28°F hard-freeze dates, about May 1 and Oct 8 and the ~160-day span between themNOAA 1991–2020 Climate Normals
- 73 documented contamination sites on the federal record near Riverdale, the closest Underground Storage Tanks record about 0.3 miles out from the town centreFederal environmental registers
- Riverdale's boundary and the 888 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~160-day seasonGrowable Ground crop-matching engine
- The ecoregion at Riverdale's own centroid, the Northwestern Glaciated PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Riverdale's 888 acres read through its county's SSURGO summaryfrom McLean County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom McLean 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 McLean County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Riverdale's 888 acreswhy one lot differs from the next →
- Which side of Riverdale you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 888 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.3 miles 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 Riverdale-wide figureread your own land →
More in North Dakota
Wider growing context
What grows across North DakotaRiverdale sits outside our named growing regions, so North Dakota as a whole is its closest context here.
Nearby growing guides