Iowa spans USDA hardiness zones 4b-5b, with a growing season of about 170 frost-free days — a true four-season rhythm: spring greens, a full summer main crop, and a fall window that rewards planning.
The raw materials of the growing year here: 26-36 inches of annual rainfall, a median of roughly 2,900 growing-degree days (base 50°F), and about 1,500 winter chill hours for tree fruit. Underfoot it's mostly prairie loess, silt loam, clay loam, and alluvial — and how those drain decides more about crop success than almost anything else. The conditions favor sweet corn, tomato, apple, and grape, among others — though every individual site edits that list with its own soil, sun, and drainage.
Grounded inUSDA PHZM 2023•NOAA Climate Normals•USDA NRCS SSURGO•GDD aggregate (Cornell CALS)•Chill-hour aggregate (MSU Extension)•EPA FRS•USDA PLANTS•Growable Ground suitability scoring
Iowa spans zones 4b-5b, but your yard sits in exactly one — and slope, tree cover, and low spots nudge it further. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Distinct growing regions within Iowa — each has its own zones, soils, and signature crops.
USDA Zones
4b-5b
USDA PHZM 2023
Last Frost
Apr 20 - May 15
NOAA 30-yr Normals
First Frost
Sep 25 - Oct 15
NOAA 30-yr Normals
Annual Rainfall
26-36 inches
NOAA Climate Normals
Zone maps are averages across Iowa. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
The soil types that dominate Iowa — how each drains decides more about crop success than almost anything else. Tap any soil to learn what it is and how to work with it.
Drainage
Good — it absorbs rain readily and holds it in reach of roots — but it erodes faster than any other soil when left bare on a slope.
What thrives
Nearly everything: corn, small grains, and the full vegetable garden thrive in loess country, which is exactly why so much of it is farmed.
Drainage
Moderate. Silt holds water well and releases it steadily, though the fine particles can crust after hard rain and compact under traffic.
What thrives
The full vegetable garden does well here, and small grains, corn, and leafy greens are classic silt-loam crops. Its steady moisture suits shallow-rooted plants that dislike drought stress.
No verified open-license photo yet — this loam is close kin to the loam and silt-loam profiles above.
Drainage
Slow to moderate. Water lingers in the root zone longer than in loam, which is a gift in dry summers and a challenge in wet springs.
What thrives
Heavy feeders that appreciate steady moisture — brassicas, corn, beans, and many fruit trees. Perennials with strong root systems establish well once they are through the first season.
Drainage
Usually good: rivers sort their loads, and most alluvial soils have enough sand and silt to move water while holding plenty for roots. Low-lying pockets can run wet.
What thrives
Nearly everything — vegetables, orchards, vines, and berries all prosper on alluvium. Its depth lets roots go as far down as they care to.
Soil data: USDA NRCS SSURGO · Soil types explained
Plants well-suited to Iowa's climate, soils, and growing season — each links to its full growing profile.
Rarely: the season closes in stages, not all at once, and each stage has its crops. Across Iowa, cool-season planting typically opens about four weeks before the local last hard freeze — county medians put that freeze near Apr 1, with the middle half of counties between Mar 27 and Apr 5 (NOAA 1991–2020 climate normals). Tender transplants wait two to three weeks past it, and fall planting counts back from first freezes mostly between Nov 2 and Nov 10 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
The plants Iowa put its name on — cultural emblems, not growing recommendations.
Wild prairie rose
Rosa arkansana
Designated 1897.
Oak
Quercus spp.
Designated 1961.
Plants the USDA PLANTS Database documents as native and present in Iowa — a real per-state range, not just a zone match. Presence is statewide, so a plant may still be uncommon in your specific county; your state’s Cooperative Extension or a native-plant society is the local authority.
US-native plants whose hardiness range overlaps Iowa’s USDA zones 4b-5b but which USDA PLANTS doesn’t map to a single state range here. Zone overlap is a starting filter, not a range map.
What an experienced grower plans around here — each one has a move.
Cold winters reaching -20F or below
Choose perennials rated a zone hardier than yours — Iowa winters test the margins, and the margin is where plants are lost.
Variable spring weather delays planting
Let soil temperature and your local frost normal call the start, not the calendar — a two-week wait beats a replant.
Wind exposure on open prairies desiccates plants
Even a simple windbreak — a shrub row, a snow fence, a tall cover crop — cuts wind desiccation dramatically.
For cultivar selection, pest pressure, and planting-time guidance specific to Iowa, the Iowa State University Extension and Outreach is the authoritative local source.
Safe to Grow Here?What the federal record shows across Iowa — and how to grow with it.
We checked the federal record across Iowa — 28,062 documented sites across 8 of the 9 source types we track.
The most significant on record: 122 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Iowa carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Severity Distribution
across Iowa
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Iowa, Nitrate runs higher than the national average — 8,028 sites nearby. 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).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
State averages sketch the shape. Your soil, sun exposure, drainage, and microclimate decide what actually takes. Pull a site-specific report for your exact parcel.
Enter your address. We read your soil, sun, drainage, and frost dates, then score 1,112 plants against the real conditions on your land.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Iowa spans USDA hardiness zones 4b-5b, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
Rarely: the season closes in stages, not all at once, and each stage has its crops. Across Iowa, cool-season planting typically opens about four weeks before the local last hard freeze — county medians put that freeze near Apr 1, with the middle half of counties between Mar 27 and Apr 5 (NOAA 1991–2020 climate normals). Tender transplants wait two to three weeks past it, and fall planting counts back from first freezes mostly between Nov 2 and Nov 10 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
Across Iowa, the middle half of counties see their last hard freeze (28°F) between about Mar 27 and Apr 5, with a county median near Apr 1 (NOAA 1991–2020 climate normals). That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
Measured between 28°F hard freezes, growing seasons across Iowa's counties mostly run about 211 to 229 days, with a county median near 219 (NOAA 1991–2020 climate normals). Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
Iowa's zones 4b-5b support a wide range — strong performers include Sweet Corn, Tomato, Apple, Grape, and Hosta. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Officially, Iowa spans USDA zones 4b-5b (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
The federal record across Iowa runs heavier than most — 28,062 documented sites — 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.
Start with three facts. Iowa spans USDA zones 4b-5b, which sets what survives winter; last hard freezes range from about Mar 27 to Apr 5 across its counties (NOAA 1991–2020 climate normals); and 28,062 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Iowa average. Your yard writes its own version — we read soil, sun, drainage, and frost at your exact address. Try it for 14 days — no card required.
Explore growing conditions by county — each has its own zone range and land area.
Explore growing conditions by city or town in Iowa.
