Garwin, Iowa, sits in USDA hardiness zone 5a — a zone band wide enough that plant choice, not possibility, is the interesting question.
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 Garwin, 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 Garwin 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 Garwin — soil, climate, flood, and parcel records. How we handle your address.
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Garwin — the short answer
Garwin, Iowa: USDA zone 5a, about 188 days between hard freezes, across 644 acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 15
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 20
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~188
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 644 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 Garwin's average, not your lot's — a low corner or a tree line moves it. Against Garwin's 188-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Garwin
Each reading below is measured for Garwin itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredGarwin runs about 188 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
MeasuredGarwin 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 Garwin is in
Garwin sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Garwin's own centroid rather than borrowed from Tama County.
What Grows in Garwin
Every plant below cleared Garwin's own zone 5a and its 188-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Garwin?
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 18; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 15 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 20 — 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 Garwin
Closest first, within ~10 miles of Garwin. Listing isn't leaking, and distance isn't exposure.
- PRONTO MARKETUnderground Storage Tanks · 650 ft
- 084N16W14ABA 1912Garwin 1Nitrate · 750 ft
- 084N16W14ABA 01663 1943Garwin 2Nitrate · 750 ft
- GARWIN COMMUNITY SCHOOLUnderground Storage Tanks · 1200 ft
- IOWA RIVER FS INCUnderground Storage Tanks · 1200 ft
- GMG HIGH SCHOOLBrownfields · 1300 ft
- C & C SVC CTRBrownfields · 1300 ft
- LARRYS DXUnderground Storage Tanks · 1400 ft
- TAMA COUNTYUnderground Storage Tanks · 1500 ft
- MARLEY BACONUnderground Storage Tanks · 1.1 mi
- 085N15W32CBB 01424 1941Nitrate · 3.5 mi
- 085N16W32ACC 01674 1943Union Grove Rec ReserveNitrate · 4.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Garwin'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 Garwin.
Total Sites
163
within ~10 miles of Garwin
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
within ~10 miles of Garwin
Severity Distribution
within ~10 miles of Garwin
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Garwin, Nitrate runs higher than the national average — 80 sites within ~10 miles of Garwin. 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 Garwin
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 Garwin average
Your land is one point inside Garwin
Everything above resolves to Garwin as a whole — one PHZM band and one 28°F frost record, read across 644 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 Garwin Average
Garwin Average
- ●USDA Zones 5a, averaged across Garwin
- ●One soil character for all of Garwin
- ●Frost dates read at Garwin's scale: Apr 15 to Oct 20
YOUR Parcel
- ✓Your exact zone, not Garwin's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Garwin
Pull a site-specific report for your exact address in Garwin, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Garwin averages can't show:
We read public map data around Garwin — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Garwin average
How we know this about Garwin
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 Garwin’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 Garwin
When does frost risk typically end in Garwin?
The last hard freeze (28°F) in Garwin typically lands around Apr 15, 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 6.
When is the first frost in Garwin?
The first hard freeze (28°F) in Garwin typically arrives around Oct 20, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 6, so the watching starts about Sep 20 — about 188 days after the spring freeze cleared.
How long is the growing season in Garwin?
Measured between 28°F hard freezes, Garwin sees about 188 frost-free days — roughly Apr 15 through Oct 20, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 6 to Oct 6, about 153 days.
Is the soil safe to grow vegetables in Garwin?
The federal record around Garwin shows 163 documented sites, mostly Nitrate entries (80), the nearest Underground Storage Tanks record about 0.1 miles 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 Garwin?
From about Sep 20 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 20 (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 20. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Garwin's scale — its 5a band and its 188-day season. Your yard writes its own version of Garwin'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 Garwin’s own scale
6 of the readings below were taken at Garwin's own scale — its own ~188-day season between 28°F freezes, the 644 acres it covers and 163 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Garwin's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Garwin's own 28°F hard-freeze dates, about Apr 15 and Oct 20 and the ~188-day span between themNOAA 1991–2020 Climate Normals
- 163 documented contamination sites on the federal record near Garwin, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Garwin's boundary and the 644 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~188-day seasonGrowable Ground crop-matching engine
- The ecoregion at Garwin'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 Garwin's 644 acres read through its county's SSURGO summaryfrom Tama County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Tama 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 Tama County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Garwin's 644 acreswhy one lot differs from the next →
- Which side of Garwin you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 644 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.1 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 Garwin-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaGarwin sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides