Norwalk, Iowa, sits in USDA hardiness zone 5b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Well-matched crops include cabbage, blueberry, lavender, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Norwalk, 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 Norwalk 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 Norwalk — soil, climate, flood, and parcel records. How we handle your address.
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Norwalk — the short answer
Norwalk, Iowa: USDA zone 5b, about 206 days between hard freezes, across 7K acres of city.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 29
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~206
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 7K 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 5b is Norwalk's average, not your lot's — a low corner or a tree line moves it. Against Norwalk's 206-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Norwalk
Each reading below is measured for Norwalk itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredNorwalk runs about 206 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredNorwalk sits in USDA hardiness zone 5b.
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 Norwalk is in
Norwalk sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Norwalk's own centroid rather than borrowed from Warren County.
What Grows in Norwalk
Every plant below cleared Norwalk's own zone 5b and its 206-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Norwalk?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Mar 9; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 6 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 29 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
What's on the federal record near Norwalk
Closest first, within ~10 miles of Norwalk. Listing isn't leaking, and distance isn't exposure.
- U S WESTUnderground Storage Tanks · 0.6 mi
- Not KnownUnderground Storage Tanks · 0.6 mi
- CASEYS GENERAL STORE 3422Underground Storage Tanks · 0.6 mi
- 077N25W13ABD 01358 1940Nitrate · 0.9 mi
- KUM & GO #240Underground Storage Tanks · 0.9 mi
- CASEY''S GENERAL STOREUnderground Storage Tanks · 0.9 mi
- MCANINCH CORPORATIONUnderground Storage Tanks · 1.0 mi
- 077N25W13AAC FRITOS NO 1Nitrate · 1.0 mi
- KUM & GO #239Underground Storage Tanks · 1.0 mi
- 077N25W13AAB 03663 1949Norwalk 1Nitrate · 1.0 mi
- FORMER SKELLY STATIONUnderground Storage Tanks · 1.0 mi
- CASEY''S GENERAL STORE 2568Underground Storage Tanks · 1.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Norwalk'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 Norwalk.
Sources Checked
within ~10 miles of Norwalk
Severity Distribution
within ~10 miles of Norwalk
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •TRI facilities report what they release. Check the wind — downwind beds catch more of it.
Check your specific parcel in Norwalk
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 Norwalk average
Your land is one point inside Norwalk
Everything above resolves to Norwalk as a whole — one PHZM band and one 28°F frost record, read across 7K 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 Norwalk Average
Norwalk Average
- ●USDA Zones 5b, averaged across Norwalk
- ●One soil character for all of Norwalk
- ●Frost dates read at Norwalk's scale: Apr 6 to Oct 29
YOUR Parcel
- ✓Your exact zone, not Norwalk's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Norwalk
Pull a site-specific report for your exact address in Norwalk, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Norwalk averages can't show:
We read public map data around Norwalk — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Norwalk average
How we know this about Norwalk
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 Norwalk’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 Norwalk
When does frost risk typically end in Norwalk?
The last hard freeze (28°F) in Norwalk typically lands around Apr 6, 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 Apr 27.
When is the first frost in Norwalk?
The first hard freeze (28°F) in Norwalk typically arrives around Oct 29, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 15, so the watching starts about Sep 29 — about 206 days after the spring freeze cleared.
How long is the growing season in Norwalk?
Measured between 28°F hard freezes, Norwalk sees about 206 frost-free days — roughly Apr 6 through Oct 29, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 27 to Oct 15, about 171 days.
Is the soil safe to grow vegetables in Norwalk?
The federal record around Norwalk runs heavier than most — 976 documented sites, mostly Underground Storage Tanks entries (581), the nearest Underground Storage Tanks record about 0.6 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do I protect my plants from frost in Norwalk?
From about Sep 29 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 29 (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 29. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Norwalk's scale — its 5b band and its 206-day season. Your yard writes its own version of Norwalk'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 Norwalk’s own scale
6 of the readings below were taken at Norwalk's own scale — its own ~206-day season between 28°F freezes, the 7,455 acres it covers and 976 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Norwalk's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Norwalk's own 28°F hard-freeze dates, about Apr 6 and Oct 29 and the ~206-day span between themNOAA 1991–2020 Climate Normals
- 976 documented contamination sites on the federal record near Norwalk, the closest Underground Storage Tanks record about 0.6 miles out from the town centreFederal environmental registers
- Norwalk's boundary and the 7,455 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~206-day seasonGrowable Ground crop-matching engine
- The ecoregion at Norwalk'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 Norwalk's 7,455 acres read through its county's SSURGO summaryfrom Warren County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Warren 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 Warren County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Norwalk's 7,455 acreswhy one lot differs from the next →
- Which side of Norwalk you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 7,455 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.6 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 Norwalk-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaNorwalk sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides