Donnellson, Iowa, sits in USDA hardiness zone 6a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Reliable performers under these conditions include cabbage, hazelnut, lavender, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Donnellson, 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 Donnellson 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 Donnellson — soil, climate, flood, and parcel records. How we handle your address.
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Donnellson — the short answer
Donnellson, Iowa: USDA zone 6a, about 211 days between hard freezes, across 815 acres of city.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 5
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 2
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~211
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 815 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 6a is Donnellson's average, not your lot's — a low corner or a tree line moves it. Against Donnellson's 211-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Donnellson
Each reading below is measured for Donnellson itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredDonnellson runs about 211 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
MeasuredDonnellson sits in USDA hardiness zone 6a.
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 Donnellson is in
Donnellson sits in the Central Irregular Plains — EPA Level III, inside the wider Great Plains. That is read at Donnellson's own centroid rather than borrowed from Lee County.
What Grows in Donnellson
Every plant below cleared Donnellson's own zone 6a and its 211-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Donnellson?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Mar 8; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 5 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 2 — 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 Donnellson
Closest first, within ~10 miles of Donnellson. Listing isn't leaking, and distance isn't exposure.
- 068N06W33CBBA 21320 1969Donnellson 4Nitrate · 350 ft
- IDOT MAINT GARAGEUnderground Storage Tanks · 500 ft
- IOWA DEPARTMENT OF TRANSPORTATIONBrownfields · 700 ft
- DAHMS CHEVROLET INCBrownfields · 850 ft
- 068N06W33CCBB 06140 1953DonnellsonNitrate · 1200 ft
- AYER CO #40Underground Storage Tanks · 1500 ft
- DONNELLSON ELEMENTARYUnderground Storage Tanks · 1500 ft
- 068N06W33CCBB 00184 1925Donnellson 1Nitrate · 1900 ft
- BENNER''S BPUnderground Storage Tanks · 2300 ft
- 068N06W33CCBB 01173 1940Donnellson 2Nitrate · 2400 ft
- CASEY''S GENERAL STORE 2614Underground Storage Tanks · 2500 ft
- KIRCHNERS GARAGEBrownfields · 0.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Donnellson'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 Donnellson.
Sources Checked
within ~10 miles of Donnellson
Severity Distribution
within ~10 miles of Donnellson
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Donnellson, two things run higher than the national average within ~10 miles of Donnellson — Nitrate (56 sites) and Toxics Release Inventory (10 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Donnellson
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 Donnellson average
Your land is one point inside Donnellson
Everything above resolves to Donnellson as a whole — one PHZM band and one 28°F frost record, read across 815 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 Donnellson Average
Donnellson Average
- ●USDA Zones 6a, averaged across Donnellson
- ●One soil character for all of Donnellson
- ●Frost dates read at Donnellson's scale: Apr 5 to Nov 2
YOUR Parcel
- ✓Your exact zone, not Donnellson's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Donnellson
Pull a site-specific report for your exact address in Donnellson, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Donnellson averages can't show:
We read public map data around Donnellson — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Donnellson average
How we know this about Donnellson
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 Donnellson’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 Donnellson
When does frost risk typically end in Donnellson?
The last hard freeze (28°F) in Donnellson typically lands around Apr 5, 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 26.
When is the first frost in Donnellson?
The first hard freeze (28°F) in Donnellson typically arrives around Nov 2, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 19, so the watching starts about Oct 3 — about 211 days after the spring freeze cleared.
How long is the growing season in Donnellson?
Measured between 28°F hard freezes, Donnellson sees about 211 frost-free days — roughly Apr 5 through Nov 2, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 26 to Oct 19, about 176 days.
Is the soil safe to grow vegetables in Donnellson?
The federal record around Donnellson is a meaningful one — 129 documented sites, mostly Nitrate entries (56), the nearest Nitrate 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 Donnellson?
From about Oct 3 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 Nov 2 (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 Nov 2. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Donnellson's scale — its 6a band and its 211-day season. Your yard writes its own version of Donnellson'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 Donnellson’s own scale
6 of the readings below were taken at Donnellson's own scale — its own ~211-day season between 28°F freezes, the 815 acres it covers and 129 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Donnellson's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Donnellson's own 28°F hard-freeze dates, about Apr 5 and Nov 2 and the ~211-day span between themNOAA 1991–2020 Climate Normals
- 129 documented contamination sites on the federal record near Donnellson, the closest Nitrate record under a tenth of a mile out from the town centreFederal environmental registers
- Donnellson's boundary and the 815 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~211-day seasonGrowable Ground crop-matching engine
- The ecoregion at Donnellson's own centroid, the Central Irregular PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Donnellson's 815 acres read through its county's SSURGO summaryfrom Lee County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Lee 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 Lee County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Donnellson's 815 acreswhy one lot differs from the next →
- Which side of Donnellson you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 815 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate 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 Donnellson-wide figureread your own land →