Colesburg, Iowa, sits in USDA hardiness zone 5a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
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 Colesburg, 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 Colesburg 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 Colesburg — soil, climate, flood, and parcel records. How we handle your address.
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Colesburg — the short answer
Colesburg, Iowa: USDA zone 5a, about 182 days between hard freezes, across 188 acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 17
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~182
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 188 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 Colesburg's average, not your lot's — a low corner or a tree line moves it. Against Colesburg's 182-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Colesburg
Each reading below is measured for Colesburg itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredColesburg runs about 182 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
MeasuredColesburg 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 Colesburg is in
Colesburg sits in the Driftless Area — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Colesburg's own centroid, and it is not what its county reads: Delaware County is mostly Western Corn Belt Plains. The wider page above you is answering a different question about different ground.
What Grows in Colesburg
Every plant below cleared Colesburg's own zone 5a and its 182-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Colesburg?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 20; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 17 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 16 — 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 Colesburg
Closest first, within ~10 miles of Colesburg. Listing isn't leaking, and distance isn't exposure.
- EVERY''S AUTO AND TIRE CENTERUnderground Storage Tanks · 250 ft
- COLESBURG SHELLUnderground Storage Tanks · 300 ft
- FORMER THREE RIVERS FS COMPANYUnderground Storage Tanks · 300 ft
- SCHLEE GARAGEUnderground Storage Tanks · 550 ft
- 090N03W04ACCA 1946Colesburg 1Nitrate · 950 ft
- EDGEWOOD-COLESBURG COMM SCHOOLUnderground Storage Tanks · 950 ft
- KUHLMAN CONSTRUCTION COUnderground Storage Tanks · 1100 ft
- KERMIT CONSTRUCTION COUnderground Storage Tanks · 2200 ft
- 090N03W04ADA 01067 1939Colesburg 1Nitrate · 2300 ft
- MORMANN SERVICE-PetersburgUnderground Storage Tanks · 5.9 mi
- PETERSBURG FEED MILL INCUnderground Storage Tanks · 6.0 mi
- 091N02W28CAD 06874 1954Nitrate · 6.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Colesburg'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 Colesburg.
Total Sites
51
within ~10 miles of Colesburg
Risk Level
Elevated
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
within ~10 miles of Colesburg
Severity Distribution
within ~10 miles of Colesburg
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Colesburg, Nitrate runs higher than the national average — 18 sites within ~10 miles of Colesburg. That's not a problem with your land — it's information about 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 Colesburg
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 Colesburg average
Your land is one point inside Colesburg
Everything above resolves to Colesburg as a whole — one PHZM band and one 28°F frost record, read across 188 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 Colesburg Average
Colesburg Average
- ●USDA Zones 5a, averaged across Colesburg
- ●One soil character for all of Colesburg
- ●Frost dates read at Colesburg's scale: Apr 17 to Oct 16
YOUR Parcel
- ✓Your exact zone, not Colesburg's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Colesburg
Pull a site-specific report for your exact address in Colesburg, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Colesburg averages can't show:
We read public map data around Colesburg — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Colesburg average
How we know this about Colesburg
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 Colesburg’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 Colesburg
When does frost risk typically end in Colesburg?
The last hard freeze (28°F) in Colesburg typically lands around Apr 17, 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 8.
When is the first frost in Colesburg?
The first hard freeze (28°F) in Colesburg typically arrives around Oct 16, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 2, so the watching starts about Sep 16 — about 182 days after the spring freeze cleared.
How long is the growing season in Colesburg?
Measured between 28°F hard freezes, Colesburg sees about 182 frost-free days — roughly Apr 17 through Oct 16, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 8 to Oct 2, about 147 days.
Is the soil safe to grow vegetables in Colesburg?
The federal record around Colesburg is a meaningful one — 51 documented sites, mostly Underground Storage Tanks entries (27), 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 Colesburg?
From about Sep 16 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 16 (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 16. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Colesburg's scale — its 5a band and its 182-day season. Your yard writes its own version of Colesburg'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 Colesburg’s own scale
6 of the readings below were taken at Colesburg's own scale — its own ~182-day season between 28°F freezes, the 188 acres it covers and 51 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Colesburg's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Colesburg's own 28°F hard-freeze dates, about Apr 17 and Oct 16 and the ~182-day span between themNOAA 1991–2020 Climate Normals
- 51 documented contamination sites on the federal record near Colesburg, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Colesburg's boundary and the 188 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~182-day seasonGrowable Ground crop-matching engine
- Colesburg sits in the Driftless Area — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Colesburg's 188 acres read through its county's SSURGO summaryfrom Delaware County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Delaware 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 Delaware County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Colesburg's 188 acreswhy one lot differs from the next →
- Which side of Colesburg you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 188 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 Colesburg-wide figureread your own land →
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