Granville, 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.
Expect cabbage, cranberry, lavender, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Granville, 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 Granville 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 Granville — soil, climate, flood, and parcel records. How we handle your address.
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Granville — the short answer
Granville, Iowa: USDA zone 5a, about 179 days between hard freezes, across 186 acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 20
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~179
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 186 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 Granville's average, not your lot's — a low corner or a tree line moves it. Against Granville's 179-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Granville
Each reading below is measured for Granville itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredGranville runs about 179 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
MeasuredGranville 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 Granville is in
Granville sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Granville's own centroid rather than borrowed from Sioux County.
What Grows in Granville
Every plant below cleared Granville's own zone 5a and its 179-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Granville?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 23; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 20 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 16 — 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 Granville
Closest first, within ~10 miles of Granville. Listing isn't leaking, and distance isn't exposure.
- 094N43W01CA 01461 1931Granville 1Nitrate · 300 ft
- 094N43W01CDBC 1959Granville 2Nitrate · 300 ft
- T H RECYCLINGBrownfields · 600 ft
- SHORT STOP CONV STOREUnderground Storage Tanks · 1300 ft
- FARMERS COOPUnderground Storage Tanks · 1400 ft
- C-S AGROW SERVICEUnderground Storage Tanks · 0.9 mi
- BRIGHTMARK RNG FACILITY - BLACK SOILBrownfields · 3.2 mi
- HENNINGS LLCBrownfields · 3.8 mi
- 094N42W09DDDD 25964 1980IGS CRET Proj D-42Nitrate · 3.9 mi
- BRIGHTMARK RNG FACILITY - ROORDABrownfields · 5.0 mi
- ALTON RENDERING WORKS INCUnderground Storage Tanks · 5.9 mi
- WHITE OAK STATION 86Underground Storage Tanks · 5.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Granville'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 Granville.
Sources Checked
within ~10 miles of Granville
Severity Distribution
within ~10 miles of Granville
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Granville, Nitrate runs higher than the national average — 68 sites within ~10 miles of Granville. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Granville
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 Granville average
Your land is one point inside Granville
Everything above resolves to Granville as a whole — one PHZM band and one 28°F frost record, read across 186 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 Granville Average
Granville Average
- ●USDA Zones 5a, averaged across Granville
- ●One soil character for all of Granville
- ●Frost dates read at Granville's scale: Apr 20 to Oct 16
YOUR Parcel
- ✓Your exact zone, not Granville's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Granville
Pull a site-specific report for your exact address in Granville, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Granville averages can't show:
We read public map data around Granville — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Granville average
How we know this about Granville
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 Granville’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 Granville
When does frost risk typically end in Granville?
The last hard freeze (28°F) in Granville typically lands around Apr 20, 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 11.
When is the first frost in Granville?
The first hard freeze (28°F) in Granville typically arrives around Oct 16, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 2, so the watching starts about Sep 16 — about 179 days after the spring freeze cleared.
How long is the growing season in Granville?
Measured between 28°F hard freezes, Granville sees about 179 frost-free days — roughly Apr 20 through Oct 16, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 11 to Oct 2, about 144 days.
Is the soil safe to grow vegetables in Granville?
The federal record around Granville is a meaningful one — 151 documented sites, mostly Nitrate entries (68), the nearest Nitrate record under a tenth of a mile 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 Granville?
From about Sep 16 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 16 (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 16. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Granville's scale — its 5a band and its 179-day season. Your yard writes its own version of Granville'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 Granville’s own scale
6 of the readings below were taken at Granville's own scale — its own ~179-day season between 28°F freezes, the 186 acres it covers and 151 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Granville's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Granville's own 28°F hard-freeze dates, about Apr 20 and Oct 16 and the ~179-day span between themNOAA 1991–2020 Climate Normals
- 151 documented contamination sites on the federal record near Granville, the closest Nitrate record under a tenth of a mile out from the town centreFederal environmental registers
- Granville's boundary and the 186 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~179-day seasonGrowable Ground crop-matching engine
- The ecoregion at Granville'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 Granville's 186 acres read through its county's SSURGO summaryfrom Sioux County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Sioux 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 Sioux County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Granville's 186 acreswhy one lot differs from the next →
- Which side of Granville you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 186 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 Granville-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaGranville sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides