Northboro, 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.
The conditions favor cabbage, cranberry, lavender, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Even in Northboro, 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 Northboro 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 Northboro — soil, climate, flood, and parcel records. How we handle your address.
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Northboro — the short answer
Northboro, Iowa: USDA zone 5b, about 203 days between hard freezes, across 163 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 26
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~203
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 163 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 Northboro's average, not your lot's — a low corner or a tree line moves it. Against Northboro's 203-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Northboro
Each reading below is measured for Northboro itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredNorthboro runs about 203 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
MeasuredNorthboro 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 Northboro is in
Northboro sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Northboro's own centroid rather than borrowed from Page County.
What Grows in Northboro
Every plant below cleared Northboro's own zone 5b and its 203-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Northboro?
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 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 26 — 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.
What's on the federal record near Northboro
Closest first, within ~10 miles of Northboro. Listing isn't leaking, and distance isn't exposure.
- BOYLAN SERVICEUnderground Storage Tanks · 450 ft
- FSA INVENTORY PROPERTYUnderground Storage Tanks · 0.8 mi
- GIVENS SHOPUnderground Storage Tanks · 4.2 mi
- POLSLEY PROPERTYUnderground Storage Tanks · 4.5 mi
- 067N38W05BAAC 38170 1955Coin NorthNitrate · 4.6 mi
- FORMER COIN TIRE AND OILUnderground Storage Tanks · 4.6 mi
- RED OAK WATER SUPPLYPFAS · 4.7 mi
- 067N38W05BAAC 00113 1935Coin 1Nitrate · 4.8 mi
- MARRS STATIONUnderground Storage Tanks · 5.2 mi
- BOYD HAMILTON & SONUnderground Storage Tanks · 5.4 mi
- CLARINDA WATER PLANTPFAS · 8.8 mi
- COLLEGE SPRINGS OIL COUnderground Storage Tanks · 9.1 mi
3 more sites are on the record inside the same radius. See them on the map
Measured from Northboro'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 Northboro.
Sources Checked
within ~10 miles of Northboro
Severity Distribution
within ~10 miles of Northboro
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •PFAS do not break down in groundwater. Irrigate from a tested source.
Check your specific parcel in Northboro
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 Northboro average
Your land is one point inside Northboro
Everything above resolves to Northboro as a whole — one PHZM band and one 28°F frost record, read across 163 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 Northboro Average
Northboro Average
- ●USDA Zones 5b, averaged across Northboro
- ●One soil character for all of Northboro
- ●Frost dates read at Northboro's scale: Apr 6 to Oct 26
YOUR Parcel
- ✓Your exact zone, not Northboro's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Northboro
Pull a site-specific report for your exact address in Northboro, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Northboro averages can't show:
We read public map data around Northboro — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Northboro average
How we know this about Northboro
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 Northboro’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 Northboro
When does frost risk typically end in Northboro?
The last hard freeze (28°F) in Northboro 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 Northboro?
The first hard freeze (28°F) in Northboro typically arrives around Oct 26, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 12, so the watching starts about Sep 26 — about 203 days after the spring freeze cleared.
How long is the growing season in Northboro?
Measured between 28°F hard freezes, Northboro sees about 203 frost-free days — roughly Apr 6 through Oct 26, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 27 to Oct 12, about 168 days.
Is the soil safe to grow vegetables in Northboro?
The federal record around Northboro is a meaningful one — 17 documented sites, mostly Underground Storage Tanks entries (9), the nearest Underground Storage Tanks 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 Northboro?
From about Sep 26 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 26 (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 26. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Northboro's scale — its 5b band and its 203-day season. Your yard writes its own version of Northboro'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 Northboro’s own scale
6 of the readings below were taken at Northboro's own scale — its own ~203-day season between 28°F freezes, the 163 acres it covers and 17 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Northboro's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Northboro's own 28°F hard-freeze dates, about Apr 6 and Oct 26 and the ~203-day span between themNOAA 1991–2020 Climate Normals
- 17 documented contamination sites on the federal record near Northboro, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Northboro's boundary and the 163 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~203-day seasonGrowable Ground crop-matching engine
- The ecoregion at Northboro'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 Northboro's 163 acres read through its county's SSURGO summaryfrom Page County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Page 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 Page County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Northboro's 163 acreswhy one lot differs from the next →
- Which side of Northboro you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 163 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks 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 Northboro-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaNorthboro sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides