Renwick, Iowa, sits in USDA hardiness zone 5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Growers here do well with cabbage, cranberry, lavender, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Renwick, 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 Renwick 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 Renwick — soil, climate, flood, and parcel records. How we handle your address.
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Renwick — the short answer
Renwick, Iowa: USDA zone 5a, about 185 days between hard freezes, across 641 acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 17
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 19
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~185
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 641 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 5a is Renwick's average, not your lot's — a low corner or a tree line moves it. Against Renwick's 185-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Renwick
Each reading below is measured for Renwick itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRenwick runs about 185 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
MeasuredRenwick sits in USDA hardiness zone 5a.
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 Renwick is in
Renwick sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Renwick's own centroid rather than borrowed from Humboldt County.
What Grows in Renwick
Every plant below cleared Renwick's own zone 5a and its 185-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Renwick?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Mar 20; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 17 (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. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
What's on the federal record near Renwick
Closest first, within ~10 miles of Renwick. Listing isn't leaking, and distance isn't exposure.
- 093N27W36ACCB 1944Nitrate · 450 ft
- 093N27W36ACD 04815 1951Renwick 2Nitrate · 750 ft
- FORMER LEHIGH CLAY PRODUCTS SITEUnderground Storage Tanks · 950 ft
- CHRIS SCHEIDERUnderground Storage Tanks · 950 ft
- 093N27W36ACDB 1938Renwick 1Nitrate · 950 ft
- FARMERS COOPERATIVE COMPANYUnderground Storage Tanks · 1400 ft
- W & S SHOPUnderground Storage Tanks · 2600 ft
- W&H COOP ""C"" STOREUnderground Storage Tanks · 2600 ft
- PIONEER HI-BRED INTERNATIONAL INCBrownfields · 0.5 mi
- RENWICK FORD INCUnderground Storage Tanks · 1.3 mi
- MCPEAK TRUCKINGUnderground Storage Tanks · 2.0 mi
- 093N27W21DD 09107 1957Nitrate · 3.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Renwick'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 Renwick.
Total Sites
71
within ~10 miles of Renwick
Risk Level
Moderate
Highest-severity
2 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Renwick
Severity Distribution
within ~10 miles of Renwick
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Renwick, Nitrate runs higher than the national average — 40 sites within ~10 miles of Renwick. 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 Renwick
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 Renwick average
Your land is one point inside Renwick
Everything above resolves to Renwick as a whole — one PHZM band and one 28°F frost record, read across 641 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 Renwick Average
Renwick Average
- ●USDA Zones 5a, averaged across Renwick
- ●One soil character for all of Renwick
- ●Frost dates read at Renwick's scale: Apr 17 to Oct 19
YOUR Parcel
- ✓Your exact zone, not Renwick's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Renwick
Pull a site-specific report for your exact address in Renwick, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Renwick averages can't show:
We read public map data around Renwick — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Renwick average
How we know this about Renwick
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 Renwick’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 Renwick
When does frost risk typically end in Renwick?
The last hard freeze (28°F) in Renwick typically lands around Apr 17, 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 8.
When is the first frost in Renwick?
The first hard freeze (28°F) in Renwick typically arrives around Oct 19, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 5, so the watching starts about Sep 19 — about 185 days after the spring freeze cleared.
How long is the growing season in Renwick?
Measured between 28°F hard freezes, Renwick sees about 185 frost-free days — roughly Apr 17 through Oct 19, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 8 to Oct 5, about 150 days.
Is the soil safe to grow vegetables in Renwick?
The federal record around Renwick shows 71 documented sites, mostly Nitrate entries (40), the nearest Nitrate record under a tenth of a mile out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Renwick?
From about Sep 19 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 19 (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 19. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Renwick's scale — its 5a band and its 185-day season. Your yard writes its own version of Renwick'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 Renwick’s own scale
6 of the readings below were taken at Renwick's own scale — its own ~185-day season between 28°F freezes, the 641 acres it covers and 71 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Renwick's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Renwick's own 28°F hard-freeze dates, about Apr 17 and Oct 19 and the ~185-day span between themNOAA 1991–2020 Climate Normals
- 71 documented contamination sites on the federal record near Renwick, the closest Nitrate record under a tenth of a mile out from the town centreFederal environmental registers
- Renwick's boundary and the 641 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~185-day seasonGrowable Ground crop-matching engine
- The ecoregion at Renwick's own centroid, the Western Corn Belt PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Renwick's 641 acres read through its county's SSURGO summaryfrom Humboldt County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Humboldt County
- The growing challenges every Iowa grower plans around — written at state scale, so they stay on the state guidefrom Iowa
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Humboldt County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Renwick's 641 acreswhy one lot differs from the next →
- Which side of Renwick you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 641 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record under a tenth of a mile 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 Renwick-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaRenwick sits outside our named growing regions, so Iowa as a whole is its closest context here.