Buchanan County, in Iowa, sits in USDA hardiness zone 5a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Reliable performers under these conditions include cabbage, cranberry, lavender, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Buchanan County holds more than one microclimate.
Soils and elevations shift across Buchanan County, so your frost dates and drainage aren't the county average. 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 Buchanan County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Buchanan County — the short answer
Buchanan County, Iowa: USDA zone 5a, about 182 days between hard freezes, across 365K acres.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 17
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 16
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~182
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 365K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 Buchanan County's average, not your lot's — a low corner or a tree line moves it. Against Buchanan County's 182-day season, see what your own ground reads.
Heat in Buchanan County
Across a year, Buchanan County accumulates about 2,530 growing degree days above 50°F, about 214 fewer than the middle Iowa county — ahead of 18 of Iowa’s 99 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Buchanan County
Across Buchanan County, the ground is predominantly Mollisols, where Kenyon, Clyde, and Floyd are the most extensive named soil series. The soil is generally poorly drained with a loam surface. Topsoil pH runs about 6.2–6.7, slightly acidic. Rainfall drains through hydrologic group C/D soils.
Soil order
Mollisols
Drainage
Poorly drained
Prime farmland
48%
Hydric soils
24%
Soil still varies lot by lot — soil types explained.
How the ground varies across Buchanan County
The USDA soil survey maps 34% of Buchanan County as poorly drained — but another 65% drains differently: 23% moderately well drained, 21% somewhat poorly drained.
Kenyon is the most extensive named soil at 18% of mapped acres, then Clyde (17%) and Floyd (12%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Buchanan County
Each reading below is measured for Buchanan County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Buchanan County are poorly drained, in hydrologic group C/D — ground that sheds water slowly.
Beds can stay saturated for days after heavy rain, and the roots of most vegetables, berries, and fruit trees suffocate or rot in soil that never drains.
Raised beds or mounded rows lift roots above the wet zone; choose water-tolerant crops for the lowest spots.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Buchanan County runs about pH 6.2–6.7, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Season length
MeasuredBuchanan County 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
MeasuredBuchanan County 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 Buchanan County is in
Buchanan County sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. One consistent ecological setting across the whole county.
What Grows in Buchanan County
We scored all 1,086 plants against Buchanan County's own USDA zone 5a and its own 182-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Iowa profile.
Is it too late to plant in Buchanan County?
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 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. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
Documented around Buchanan County
- monarch butterfly107 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Buchanan County
USGS estimates 257,629 lb of Glyphosate on Buchanan County farmland in 2019, its largest by weight, ahead of Acetochlor (154,322 lb) and Atrazine (95,415 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Buchanan County — and how to grow with it.
We checked the federal record across Buchanan County — 191 documented sites across 5 of the 9 source types we track.
The most significant on record: 8 Toxics Release Inventory facilities. Active industrial facilities reporting chemical releases to air, water, and land.
The federal record across Buchanan County is a modest one — a typical footprint for a growing area. Nothing here calls for alarm; it's worth knowing which recorded sites sit closest to where you grow, and each one on the map carries its type and location. If one turns out to be a near neighbor, a one-time soil test settles the question.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Buchanan County
Closest first, across Buchanan County. Listing isn't leaking, and distance isn't exposure.
- 088N09W02BC 04874 1951Nitrate · 1.6 mi
- EAST-CENTRAL IOWA RECUnderground Storage Tanks · 1.7 mi
- BUCHANAN COUNTY HEALTH CENTERBrownfields · 1.9 mi
- BUCHANAN COUNTY HEALTH CENTERUnderground Storage Tanks · 1.9 mi
- BUCHANAN COUNTY SHOPUnderground Storage Tanks · 1.9 mi
- GEATER MACHINING AND MANUFACTURINGBrownfields · 2.2 mi
- MIDWEST WOOD PRODUCTS INCUnderground Storage Tanks · 2.2 mi
- JENSEN TRANSPORTUnderground Storage Tanks · 2.3 mi
- PUBLIC WORKS BUILDINGUnderground Storage Tanks · 2.3 mi
- HOFFMAN BROS INCUnderground Storage Tanks · 2.5 mi
- INDEPENDENCE LIGHT PLANTUnderground Storage Tanks · 2.5 mi
- 089N09W34DDCA 01856 1943Independence 3Nitrate · 2.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Buchanan County'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 Buchanan County.
Total Sites
191
across Buchanan County
Risk Level
Moderate
Highest-severity
8 Toxics Release Inventory facilities
Sources Checked
across Buchanan County
Severity Distribution
across Buchanan County
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.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
Check your specific parcel in Buchanan County
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 Buchanan County average
Your land is one point inside Buchanan County
Everything above resolves to Buchanan County as a whole — one PHZM band and one county frost record, read across 365K 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 county 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 county average.
Your Lot vs the Buchanan County Average
Buchanan County Average
- ●USDA Zones 5a, averaged across Buchanan County
- ●One soil character for all of Buchanan County
- ●Frost dates read at Buchanan County's scale: Apr 17 to Oct 16
YOUR Parcel
- ✓Your exact zone, not Buchanan County's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Buchanan County
Pull a site-specific report for your exact address in Buchanan County, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Buchanan County averages can't show:
We read public map data around Buchanan County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Buchanan County average
How we know this about Buchanan County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Buchanan County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Buchanan County
When does frost risk typically end in Buchanan County?
The last hard freeze (28°F) in Buchanan County 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.
How long is the growing season in Buchanan County?
Measured between 28°F hard freezes, Buchanan County 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 Buchanan County?
The federal record around Buchanan County shows 191 documented sites, mostly Underground Storage Tanks entries (110), the nearest Nitrate record about 1.6 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
Everything above is measured at Buchanan County's scale — its 5a band and its 182-day season. Your yard writes its own version of Buchanan County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Iowa's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Buchanan County’s own scale
9 of the readings below were taken at Buchanan County's own scale — its own ~182-day span between 28°F freezes, the 3 most extensive soil series mapped here and 191 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Buchanan County's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Buchanan County's own 28°F hard-freeze dates and its ~182-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Buchanan CountyUSDA NRCS SSURGO
- 191 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 1.6 miles outFederal environmental registers
- Buchanan County's boundary and the 365,494 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~182-day seasonGrowable Ground crop-matching engine
- Buchanan County sitting wholly inside the Western Corn Belt PlainsUS EPA Level III Ecoregions
- Open occurrence records documented in Buchanan County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Buchanan County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Iowa grower plans around — written at state scale, so they stay on the state guidefrom Iowa
What this page can’t tell you
- How the season shifts across Buchanan County — the ~182 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Buchanan County's 365,494 acreswhy one lot differs from the next →
- Which of those 191 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Buchanan Countyread your own land →