Bon Homme County, in South Dakota, sits in USDA hardiness zone 5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Among the crops suited to this profile: cabbage, cranberry, lavender, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Bon Homme County lies within the Southeastern South Dakota Corn Belt (Sioux Falls / Big Sioux) — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Bon Homme County holds more than one microclimate.
Soils and elevations shift across Bon Homme 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 Bon Homme County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Bon Homme County — the short answer
Bon Homme County, South Dakota: USDA zone 5a, about 181 days between hard freezes, across 361K acres.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 18
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 16
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~181
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 361K 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 Bon Homme County's average, not your lot's — a low corner or a tree line moves it. Against Bon Homme County's 181-day season, see what your own ground reads.
Heat in Bon Homme County
Across a year, Bon Homme County accumulates about 2,811 growing degree days above 50°F, about 385 more than the middle South Dakota county — ahead of every other South Dakota county. 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 Bon Homme County
Across Bon Homme County, the ground is predominantly Mollisols, where Clarno, Homme, and Ethan are the most extensive named soil series. The soil is generally well drained with a loam surface. Topsoil pH runs about 6.7–7.5, neutral. Rainfall drains through hydrologic group C soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
47%
Hydric soils
10%
Soil still varies lot by lot — soil types explained.
How the ground varies across Bon Homme County
The USDA soil survey maps 65% of Bon Homme County as well drained — but another 32% drains differently: 15% somewhat poorly drained, 7% moderately well drained.
Clarno is the most extensive named soil at 21% of mapped acres, then Homme (18%) and Ethan (14%).
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 Bon Homme County
Each reading below is measured for Bon Homme 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 Bon Homme County are well drained, in hydrologic group C — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Bon Homme County runs about pH 6.7–7.5, 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
MeasuredBon Homme County runs about 181 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
MeasuredBon Homme 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 Bon Homme County is in
Bon Homme County spans 2 EPA Level III ecoregions — Northern Glaciated Plains (52%) and Northwestern Glaciated Plains (48%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Bon Homme County
We scored all 1,086 plants against Bon Homme County's own USDA zone 5a and its own 181-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 South Dakota profile.
Is it too late to plant in Bon Homme County?
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 21; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 18 (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. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
Documented around Bon Homme County
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Bon Homme County
USGS estimates 175,528 lb of Glyphosate on Bon Homme County farmland in 2019, its largest by weight, ahead of Acetochlor (36,629 lb) and Metolachlor & Metolachlor-s (26,671 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 Bon Homme County — and how to grow with it.
We checked the federal record across Bon Homme County — 290 documented sites across 5 of the 9 source types we track.
The most significant on record: 1 Superfund site (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Bon Homme County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Bon Homme County
Closest first, across Bon Homme County. Listing isn't leaking, and distance isn't exposure.
- SD DEPT OF TRANSPORTATIONUnderground Storage Tanks · 0.8 mi
- 94N59W 6ABCCNitrate · 1.0 mi
- FRANKS TRADING POST, INC.Underground Storage Tanks · 1.1 mi
- CITY OF TYNDALLUnderground Storage Tanks · 1.1 mi
- SCHIMIDT'S C STOREUnderground Storage Tanks · 1.1 mi
- BERINGERS OIL & TIRE COUnderground Storage Tanks · 1.1 mi
- CASEY GENERAL STORE #3649Underground Storage Tanks · 1.1 mi
- 94N59W 6ACNitrate · 1.2 mi
- 94N59W 6AC2Nitrate · 1.2 mi
- 94N59W 6ACBBNitrate · 1.2 mi
- SCHMIDT'S SERVICEUnderground Storage Tanks · 1.2 mi
- 94N59W 6DABANitrate · 1.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Bon Homme 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 Bon Homme County.
Total Sites
290
across Bon Homme County
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
across Bon Homme County
Severity Distribution
across Bon Homme County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Bon Homme County, Nitrate runs higher than the national average — 248 sites across Bon Homme County. 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).
Check your specific parcel in Bon Homme 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 Bon Homme County average
Your land is one point inside Bon Homme County
Everything above resolves to Bon Homme County as a whole — one PHZM band and one county frost record, read across 361K 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 Bon Homme County Average
Bon Homme County Average
- ●USDA Zones 5a, averaged across Bon Homme County
- ●One soil character for all of Bon Homme County
- ●Frost dates read at Bon Homme County's scale: Apr 18 to Oct 16
YOUR Parcel
- ✓Your exact zone, not Bon Homme County's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Bon Homme County
Pull a site-specific report for your exact address in Bon Homme County, South Dakota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Bon Homme County averages can't show:
We read public map data around Bon Homme County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Bon Homme County average
How we know this about Bon Homme 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 Bon Homme County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Bon Homme County
When does frost risk typically end in Bon Homme County?
The last hard freeze (28°F) in Bon Homme County typically lands around Apr 18, 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 9.
How long is the growing season in Bon Homme County?
Measured between 28°F hard freezes, Bon Homme County sees about 181 frost-free days — roughly Apr 18 through Oct 16, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 9 to Oct 2, about 146 days.
Is the soil safe to grow vegetables in Bon Homme County?
The federal record around Bon Homme County is a meaningful one — 290 documented sites, mostly Nitrate entries (248), the nearest Underground Storage Tanks record about 0.8 miles 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.
Everything above is measured at Bon Homme County's scale — its 5a band and its 181-day season. Your yard writes its own version of Bon Homme 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 South Dakota's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Bon Homme County’s own scale
9 of the readings below were taken at Bon Homme County's own scale — its own ~181-day span between 28°F freezes, the 3 most extensive soil series mapped here and 290 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Bon Homme County's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Bon Homme County's own 28°F hard-freeze dates and its ~181-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Bon Homme CountyUSDA NRCS SSURGO
- 290 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.8 miles outFederal environmental registers
- Bon Homme County's boundary and the 360,671 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~181-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Bon Homme County spans, Northern Glaciated Plains the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Bon Homme County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Bon Homme County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every South Dakota grower plans around — written at state scale, so they stay on the state guidefrom South Dakota
What this page can’t tell you
- How the season shifts across Bon Homme County — the ~181 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 Bon Homme County's 360,671 acreswhy one lot differs from the next →
- Which of those 290 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 Bon Homme Countyread your own land →