Fall River 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.
The conditions favor cabbage, cranberry, lavender, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Fall River County lies within the Black Hills — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Fall River County holds more than one microclimate.
Soils and elevations shift across Fall River 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 Fall River County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Fall River County — the short answer
Fall River County, South Dakota: USDA zone 5a, about 165 days between hard freezes, across 1.1M acres.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 1
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 13
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~165
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 1.1M 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 Fall River County's average, not your lot's — a low corner or a tree line moves it. Against Fall River County's 165-day season, see what your own ground reads.
Heat in Fall River County
Across a year, Fall River County accumulates about 2,392 growing degree days above 50°F, about 34 fewer than the middle South Dakota county — ahead of 29 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 Fall River County
Across Fall River County, the ground is predominantly Inceptisols, where Pierre, Minnequa, and Kyle are the most extensive named soil series. The soil is generally well drained with a clay surface. Topsoil pH runs about 7.0–7.3, neutral. Rainfall drains through hydrologic group D soils.
Soil order
Inceptisols
Drainage
Well drained
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
How the ground varies across Fall River County
The USDA soil survey maps 87% of Fall River County as well drained — but another 12% drains differently: 8% excessively drained, 4% somewhat excessively drained.
Pierre is the most extensive named soil at 32% of mapped acres, then Minnequa (5%) and Kyle (5%).
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 Fall River County
Each reading below is measured for Fall River 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 Fall River County are well drained, in hydrologic group D — 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 Fall River County runs about pH 7.0–7.3, 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
MeasuredFall River County runs about 165 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
MeasuredFall River 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 Fall River County is in
Fall River County spans 2 EPA Level III ecoregions — Northwestern Great Plains (84%) and Middle Rockies (17%). 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 Fall River County
We scored all 1,086 plants against Fall River County's own USDA zone 5a and its own 165-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 Fall River 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 Apr 3; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 1 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 13 — 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.
What gets applied to farmland in Fall River County
USGS estimates 10,492 lb of Glyphosate on Fall River County farmland in 2019, its largest by weight, ahead of 2,4-d (5,110 lb) and Chlorpyrifos (3,802 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 Fall River County — and how to grow with it.
We checked the federal record across Fall River County — 134 documented sites across 5 of the 9 source types we track.
The most significant on record: 4 Superfund sites (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 Fall River 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 Fall River County
Closest first, across Fall River County. Listing isn't leaking, and distance isn't exposure.
- 008S05E26BCAANitrate · 7.4 mi
- 008S05E17ACBBNitrate · 9.5 mi
- 008S05E16BBADNitrate · 9.6 mi
- GRIN AND BEAR IT GASUnderground Storage Tanks · 10.4 mi
- HILLS EDGE AUTO SALESUnderground Storage Tanks · 10.4 mi
- HOT SPRINGSPFAS · 10.5 mi
- 008S06E14ADCDNitrate · 11.6 mi
- FALL RIVER FEEDLOTS INCUnderground Storage Tanks · 12.1 mi
- 10S 3E15BANitrate · 12.4 mi
- SD DEPT OF TRANSPORTATIONUnderground Storage Tanks · 13.2 mi
- 007S06E34CBDBNitrate · 13.2 mi
- 007S05E26AACANitrate · 13.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Fall River 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 Fall River County.
Total Sites
134
across Fall River County
Risk Level
Elevated
Highest-severity
4 Superfund sites (none NPL-listed)
Sources Checked
across Fall River County
Severity Distribution
across Fall River County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Fall River County, two things run higher than the national average across Fall River County — Nitrate (84 sites) and Superfund (4 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.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Fall River 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 Fall River County average
Your land is one point inside Fall River County
Everything above resolves to Fall River County as a whole — one PHZM band and one county frost record, read across 1.1M 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 Fall River County Average
Fall River County Average
- ●USDA Zones 5a, averaged across Fall River County
- ●One soil character for all of Fall River County
- ●Frost dates read at Fall River County's scale: May 1 to Oct 13
YOUR Parcel
- ✓Your exact zone, not Fall River County's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Fall River County
Pull a site-specific report for your exact address in Fall River County, South Dakota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Fall River County averages can't show:
We read public map data around Fall River County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Fall River County average
How we know this about Fall River 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 Fall River County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Fall River County
When does frost risk typically end in Fall River County?
The last hard freeze (28°F) in Fall River County typically lands around May 1, 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 22.
How long is the growing season in Fall River County?
Measured between 28°F hard freezes, Fall River County sees about 165 frost-free days — roughly May 1 through Oct 13, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 22 to Sep 29, about 130 days.
Is the soil safe to grow vegetables in Fall River County?
The federal record around Fall River County is a meaningful one — 134 documented sites, mostly Nitrate entries (84), the nearest Nitrate record about 7.4 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 Fall River County's scale — its 5a band and its 165-day season. Your yard writes its own version of Fall River 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 Fall River County’s own scale
8 of the readings below were taken at Fall River County's own scale — its own ~165-day span between 28°F freezes, the 3 most extensive soil series mapped here and 134 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Fall River County's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Fall River County's own 28°F hard-freeze dates and its ~165-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Fall River CountyUSDA NRCS SSURGO
- 134 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 7.4 miles outFederal environmental registers
- Fall River County's boundary and the 1,113,528 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~165-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Fall River County spans, Northwestern Great Plains the largestUS EPA Level III Ecoregions
- Which agricultural compounds go onto Fall River 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 Fall River County — the ~165 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 Fall River County's 1,113,528 acreswhy one lot differs from the next →
- Which of those 134 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 Fall River Countyread your own land →