Douglas County, in South Dakota, sits in USDA hardiness zone 5a — a zone band wide enough that plant choice, not possibility, is the interesting question.
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.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Douglas County holds more than one microclimate.
Soils and elevations shift across Douglas 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 Douglas County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Douglas County — the short answer
Douglas County, South Dakota: USDA zone 5a, about 181 days between hard freezes, across 276K 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 18
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~181
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 276K 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 Douglas County's average, not your lot's — a low corner or a tree line moves it. Against Douglas County's 181-day season, see what your own ground reads.
Heat in Douglas County
Across a year, Douglas County accumulates about 2,778 growing degree days above 50°F, about 352 more than the middle South Dakota county — ahead of 64 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 Douglas County
Across Douglas County, the ground is predominantly Mollisols, where Eakin, Highmore, and Ethan are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 6.4–6.9, neutral. Rainfall drains through hydrologic group C soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
10%
Hydric soils
13%
Soil still varies lot by lot — soil types explained.
How the ground varies across Douglas County
The USDA soil survey maps 72% of Douglas County as well drained — but another 27% drains differently: 15% moderately well drained, 7% poorly drained.
Eakin is the most extensive named soil at 16% of mapped acres, then Highmore (14%) and Ethan (13%).
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 Douglas County
Each reading below is measured for Douglas 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 Douglas 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 Douglas County runs about pH 6.4–6.9, 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
MeasuredDouglas 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
MeasuredDouglas 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 Douglas County is in
Douglas County sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. One consistent ecological setting across the whole county.
What Grows in Douglas County
We scored all 1,086 plants against Douglas 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 Douglas County?
For most of the year, no — what changes is which crops still fit the days remaining. 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 18 — 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 Douglas County
USGS estimates 136,574 lb of Glyphosate on Douglas County farmland in 2019, its largest by weight, ahead of Acetochlor (25,782 lb) and Metolachlor & Metolachlor-s (19,906 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 Douglas County — and how to grow with it.
We checked the federal record across Douglas County — 151 documented sites across 4 of the 9 source types we track.
The most significant on record: 2 Toxics Release Inventory facilities. Active industrial facilities reporting chemical releases to air, water, and land.
The federal record across Douglas 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 Douglas County
Closest first, across Douglas County. Listing isn't leaking, and distance isn't exposure.
- 99N63W 7BBBBNitrate · 1.5 mi
- 99N64W25BCCCNitrate · 1.9 mi
- 99N63W 5CCCCNitrate · 2.1 mi
- 99N63W20DDCANitrate · 2.5 mi
- 99N64W 3BBANitrate · 2.7 mi
- DOUGLAS CO HWY DEPT SHOPUnderground Storage Tanks · 2.9 mi
- 99N64W 3BADD2Nitrate · 3.2 mi
- DEA - CLANDESTINE DRUG LABBrownfields · 3.3 mi
- CHS FARMERS ALLIANCE - CORSICA FEEDToxics Release Inventory · 3.3 mi
- 99N64W 3BCAANitrate · 3.3 mi
- FORMER VAN BROTHERS INCUnderground Storage Tanks · 3.3 mi
- DAKOTA MFG CO INCToxics Release Inventory · 3.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Douglas 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 Douglas County.
Total Sites
151
across Douglas County
Risk Level
Moderate
Highest-severity
2 Toxics Release Inventory facilities
Sources Checked
across Douglas County
Severity Distribution
across Douglas County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Douglas County, Nitrate runs higher than the national average — 120 sites across Douglas 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 Douglas 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 Douglas County average
Your land is one point inside Douglas County
Everything above resolves to Douglas County as a whole — one PHZM band and one county frost record, read across 276K 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 Douglas County Average
Douglas County Average
- ●USDA Zones 5a, averaged across Douglas County
- ●One soil character for all of Douglas County
- ●Frost dates read at Douglas County's scale: Apr 20 to Oct 18
YOUR Parcel
- ✓Your exact zone, not Douglas County's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Douglas County
Pull a site-specific report for your exact address in Douglas County, South Dakota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Douglas County averages can't show:
We read public map data around Douglas County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Douglas County average
How we know this about Douglas 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 Douglas County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Douglas County
When does frost risk typically end in Douglas County?
The last hard freeze (28°F) in Douglas 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 Douglas County?
Measured between 28°F hard freezes, Douglas County sees about 181 frost-free days — roughly Apr 20 through Oct 18, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 11 to Oct 4, about 146 days.
Is the soil safe to grow vegetables in Douglas County?
The federal record around Douglas County shows 151 documented sites, mostly Nitrate entries (120), the nearest Nitrate record about 1.5 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 Douglas County's scale — its 5a band and its 181-day season. Your yard writes its own version of Douglas 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 Douglas County’s own scale
8 of the readings below were taken at Douglas County's own scale — its own ~181-day span between 28°F freezes, the 3 most extensive soil series mapped here and 151 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Douglas County's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Douglas 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 Douglas CountyUSDA NRCS SSURGO
- 151 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 1.5 miles outFederal environmental registers
- Douglas County's boundary and the 276,352 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~181-day seasonGrowable Ground crop-matching engine
- Douglas County sitting wholly inside the Northwestern Glaciated PlainsUS EPA Level III Ecoregions
- Which agricultural compounds go onto Douglas 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 Douglas 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 Douglas County's 276,352 acreswhy one lot differs from the next →
- Which of those 151 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 Douglas Countyread your own land →