Hanson County, in South Dakota, sits in USDA hardiness zone 5a — a zone band wide enough that plant choice, not possibility, is the interesting question.
These conditions suit cabbage, cranberry, lavender, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Hanson County lies within the James River Valley — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Hanson County holds more than one microclimate.
Soils and elevations shift across Hanson 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 Hanson County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Hanson County — the short answer
Hanson County, South Dakota: USDA zone 5a, about 179 days between hard freezes, across 278K acres.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 20
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 16
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~179
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 278K 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 Hanson County's average, not your lot's — a low corner or a tree line moves it. Against Hanson County's 179-day season, see what your own ground reads.
Heat in Hanson County
Across a year, Hanson County accumulates about 2,701 growing degree days above 50°F, about 275 more than the middle South Dakota county — ahead of 55 of South Dakota’s 66 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 Hanson County
Across Hanson County, the ground is predominantly Mollisols, where Clarno, Bonilla, and Tetonka are the most extensive named soil series. The soil is generally well drained with a loam surface. Topsoil pH runs about 6.7, neutral. Rainfall drains through hydrologic group B soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
54%
Hydric soils
14%
Soil still varies lot by lot — soil types explained.
How the ground varies across Hanson County
The USDA soil survey maps 67% of Hanson County as well drained — but another 33% drains differently: 15% moderately well drained, 12% poorly drained.
Clarno is the most extensive named soil at 34% of mapped acres, then Bonilla (12%) and Tetonka (9%).
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 Hanson County
Each reading below is measured for Hanson 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 Hanson County are well drained, in hydrologic group B — 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 Hanson County runs about pH 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
MeasuredHanson County runs about 179 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
MeasuredHanson 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 Hanson County is in
Hanson County sits in the Northern Glaciated Plains — EPA Level III, inside the wider Great Plains. One consistent ecological setting across the whole county.
What Grows in Hanson County
We scored all 1,086 plants against Hanson County's own USDA zone 5a and its own 179-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 Hanson 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 23; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 20 (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. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
What gets applied to farmland in Hanson County
USGS estimates 155,462 lb of Glyphosate on Hanson County farmland in 2019, its largest by weight, ahead of Acetochlor (95,783 lb) and Atrazine (46,110 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 Hanson County — and how to grow with it.
We checked the federal record across Hanson County — 92 documented sites across 3 of the 9 source types we track.
The most significant on record: 4 brownfield sites. Former commercial or industrial land where legacy contamination may persist.
The federal record across Hanson 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 Hanson County
Closest first, across Hanson County. Listing isn't leaking, and distance isn't exposure.
- WESTOWN TEXACOUnderground Storage Tanks · 1.4 mi
- HANSON CO HWY DEPTUnderground Storage Tanks · 1.6 mi
- HANSON SCHOOL DISTUnderground Storage Tanks · 1.8 mi
- HANSON SCHOOLBrownfields · 1.8 mi
- 102N58W10BCAD (3)Nitrate · 2.0 mi
- 102N58W10BCADNitrate · 2.0 mi
- 102N58W10BCAD2Nitrate · 2.0 mi
- KIPS DRIVE INNUnderground Storage Tanks · 2.0 mi
- FARMERS ALLIANCE & UNITED ENERGYUnderground Storage Tanks · 2.0 mi
- HANSON COUNTY OIL PRODUCERS, LLCBrownfields · 2.3 mi
- 104N58W33DDDD (4)Nitrate · 5.5 mi
- NUSTAR LOGISTICS, L.P. - MITCHELL REFINED PRODUCTS TERMINALBrownfields · 6.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Hanson 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 Hanson County.
Severity Distribution
across Hanson County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Hanson County, Nitrate runs higher than the national average — 74 sites across Hanson 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 Hanson 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 Hanson County average
Your land is one point inside Hanson County
Everything above resolves to Hanson County as a whole — one PHZM band and one county frost record, read across 278K 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 Hanson County Average
Hanson County Average
- ●USDA Zones 5a, averaged across Hanson County
- ●One soil character for all of Hanson County
- ●Frost dates read at Hanson County's scale: Apr 20 to Oct 16
YOUR Parcel
- ✓Your exact zone, not Hanson County's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Hanson County
Pull a site-specific report for your exact address in Hanson County, South Dakota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Hanson County averages can't show:
We read public map data around Hanson County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Hanson County average
How we know this about Hanson 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 Hanson County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Hanson County
When does frost risk typically end in Hanson County?
The last hard freeze (28°F) in Hanson County typically lands around Apr 20, 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 11.
How long is the growing season in Hanson County?
Measured between 28°F hard freezes, Hanson County sees about 179 frost-free days — roughly Apr 20 through Oct 16, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 11 to Oct 2, about 144 days.
Is the soil safe to grow vegetables in Hanson County?
The federal record around Hanson County shows 92 documented sites, mostly Nitrate entries (74), the nearest Underground Storage Tanks record about 1.4 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 Hanson County's scale — its 5a band and its 179-day season. Your yard writes its own version of Hanson 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 Hanson County’s own scale
8 of the readings below were taken at Hanson County's own scale — its own ~179-day span between 28°F freezes, the 3 most extensive soil series mapped here and 92 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Hanson County's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Hanson County's own 28°F hard-freeze dates and its ~179-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Hanson CountyUSDA NRCS SSURGO
- 92 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 1.4 miles outFederal environmental registers
- Hanson County's boundary and the 278,132 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~179-day seasonGrowable Ground crop-matching engine
- Hanson County sitting wholly inside the Northern Glaciated PlainsUS EPA Level III Ecoregions
- Which agricultural compounds go onto Hanson 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 Hanson County — the ~179 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 Hanson County's 278,132 acreswhy one lot differs from the next →
- Which of those 92 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 Hanson Countyread your own land →