Hawarden, Iowa, sits in USDA hardiness zone 5a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Crops well matched to these conditions include cabbage, cranberry, lavender, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Hawarden, 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 Hawarden 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 Hawarden — soil, climate, flood, and parcel records. How we handle your address.
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Hawarden — the short answer
Hawarden, Iowa: USDA zone 5a, about 175 days between hard freezes, across 2K acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 21
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 13
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~175
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 2K 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 Hawarden's average, not your lot's — a low corner or a tree line moves it. Against Hawarden's 175-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Hawarden
Each reading below is measured for Hawarden itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHawarden runs about 175 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
MeasuredHawarden 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 Hawarden is in
Hawarden sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Hawarden's own centroid rather than borrowed from Sioux County.
What Grows in Hawarden
Every plant below cleared Hawarden's own zone 5a and its 175-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Hawarden?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 24; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 21 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 13 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
What's on the federal record near Hawarden
Closest first, within ~10 miles of Hawarden. Listing isn't leaking, and distance isn't exposure.
- CITY OF HAWARDENUnderground Storage Tanks · 600 ft
- L G EVERIST INCUnderground Storage Tanks · 600 ft
- 095N48W35BDDC 1931Hawarden 2Nitrate · 1300 ft
- CASEY''S GENERAL STORE #1570Underground Storage Tanks · 1600 ft
- QUICK CORNER INCUnderground Storage Tanks · 1700 ft
- AMOCO SERVICEUnderground Storage Tanks · 1700 ft
- NORTHSIDE BODY SHOPBrownfields · 1800 ft
- 095N48W35BCAD 1924Hawarden 1Nitrate · 1900 ft
- CASEYS GENERAL STORE 2687Underground Storage Tanks · 2100 ft
- CASEY''S GENERAL STORE #3229Underground Storage Tanks · 2100 ft
- HAWARDEN AGRI CENTERUnderground Storage Tanks · 2200 ft
- ERICSON AUTO BODYBrownfields · 2300 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Hawarden'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 Hawarden.
Total Sites
113
within ~10 miles of Hawarden
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Hawarden
Severity Distribution
within ~10 miles of Hawarden
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Hawarden, two things run higher than the national average within ~10 miles of Hawarden — Nitrate (56 sites) and Toxics Release Inventory (7 sites). 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.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Hawarden
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 Hawarden average
Your land is one point inside Hawarden
Everything above resolves to Hawarden as a whole — one PHZM band and one 28°F frost record, read across 2K 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 Hawarden Average
Hawarden Average
- ●USDA Zones 5a, averaged across Hawarden
- ●One soil character for all of Hawarden
- ●Frost dates read at Hawarden's scale: Apr 21 to Oct 13
YOUR Parcel
- ✓Your exact zone, not Hawarden's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Hawarden
Pull a site-specific report for your exact address in Hawarden, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Hawarden averages can't show:
We read public map data around Hawarden — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Hawarden average
How we know this about Hawarden
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 Hawarden’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 Hawarden
When does frost risk typically end in Hawarden?
The last hard freeze (28°F) in Hawarden typically lands around Apr 21, 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 12.
When is the first frost in Hawarden?
The first hard freeze (28°F) in Hawarden typically arrives around Oct 13, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 29, so the watching starts about Sep 13 — about 175 days after the spring freeze cleared.
How long is the growing season in Hawarden?
Measured between 28°F hard freezes, Hawarden sees about 175 frost-free days — roughly Apr 21 through Oct 13, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 12 to Sep 29, about 140 days.
Is the soil safe to grow vegetables in Hawarden?
The federal record around Hawarden is a meaningful one — 113 documented sites, mostly Nitrate entries (56), the nearest Underground Storage Tanks record about 0.1 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 Hawarden?
From about Sep 13 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 13 (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 13. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Hawarden's scale — its 5a band and its 175-day season. Your yard writes its own version of Hawarden'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 Hawarden’s own scale
6 of the readings below were taken at Hawarden's own scale — its own ~175-day season between 28°F freezes, the 1,772 acres it covers and 113 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Hawarden's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Hawarden's own 28°F hard-freeze dates, about Apr 21 and Oct 13 and the ~175-day span between themNOAA 1991–2020 Climate Normals
- 113 documented contamination sites on the federal record near Hawarden, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Hawarden's boundary and the 1,772 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~175-day seasonGrowable Ground crop-matching engine
- The ecoregion at Hawarden'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 Hawarden's 1,772 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 Hawarden's 1,772 acreswhy one lot differs from the next →
- Which side of Hawarden you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,772 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 Hawarden-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaHawarden sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides