Fairfax, South Dakota, sits in USDA hardiness zone 5a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
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.
Even in Fairfax, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Fairfax lot. 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 Fairfax — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Fairfax — the short answer
Fairfax, South Dakota: USDA zone 5a, about 178 days between hard freezes, across 194 acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 21
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~178
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 194 acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 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 Fairfax's average, not your lot's — a low corner or a tree line moves it. Against Fairfax's 178-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Fairfax
Each reading below is measured for Fairfax itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredFairfax runs about 178 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
MeasuredFairfax 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 Fairfax is in
Fairfax sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Fairfax's own centroid rather than borrowed from Gregory County.
What Grows in Fairfax
Every plant below cleared Fairfax's own zone 5a and its 178-day season. Each card opens that plant's South Dakota profile. How we score.
Is it too late to plant in Fairfax?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 24; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 21 (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.
What's on the federal record near Fairfax
Closest first, within ~10 miles of Fairfax. Listing isn't leaking, and distance isn't exposure.
- ROSEBUD FARMERS UNIONUnderground Storage Tanks · 350 ft
- SD DEPT OF TRANSPORTATIONUnderground Storage Tanks · 3.8 mi
- 95N68W 6CAADNitrate · 3.9 mi
- 95N69W 1DDDDNitrate · 3.9 mi
- 95N68W 6ACDBNitrate · 3.9 mi
- 95N68W 6ACDANitrate · 3.9 mi
- 95N68W 6ACADNitrate · 3.9 mi
- 95N68W 6ACANitrate · 4.0 mi
- 95N68W 6ACAB2Nitrate · 4.0 mi
- 95N68W 6ACABNitrate · 4.0 mi
- 95N69W14AAAANitrate · 4.1 mi
- 95N68W 6BCDDNitrate · 4.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Fairfax'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 Fairfax.
Severity Distribution
within ~10 miles of Fairfax
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Fairfax, Nitrate runs higher than the national average — 32 sites within ~10 miles of Fairfax. That's not a problem with your land — it's information about 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 Fairfax
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 Fairfax average
Your land is one point inside Fairfax
Everything above resolves to Fairfax as a whole — one PHZM band and one 28°F frost record, read across 194 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 town 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 local average.
Your Lot vs the Fairfax Average
Fairfax Average
- ●USDA Zones 5a, averaged across Fairfax
- ●One soil character for all of Fairfax
- ●Frost dates read at Fairfax's scale: Apr 21 to Oct 16
YOUR Parcel
- ✓Your exact zone, not Fairfax's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Fairfax
Pull a site-specific report for your exact address in Fairfax, South Dakota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Fairfax averages can't show:
We read public map data around Fairfax — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Fairfax average
How we know this about Fairfax
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Fairfax’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Fairfax
When does frost risk typically end in Fairfax?
The last hard freeze (28°F) in Fairfax typically lands around Apr 21, 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 12.
When is the first frost in Fairfax?
The first hard freeze (28°F) in Fairfax typically arrives around Oct 16, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 2, so the watching starts about Sep 16 — about 178 days after the spring freeze cleared.
How long is the growing season in Fairfax?
Measured between 28°F hard freezes, Fairfax sees about 178 frost-free days — roughly Apr 21 through Oct 16, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 12 to Oct 2, about 143 days.
Is the soil safe to grow vegetables in Fairfax?
The federal record around Fairfax is light — 43 documented sites across the 9 federal source types we checked, mostly Nitrate entries (32), the nearest Underground Storage Tanks record under a tenth of a mile out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do I protect my plants from frost in Fairfax?
From about Sep 16 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Oct 16 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Oct 16. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Fairfax's scale — its 5a band and its 178-day season. Your yard writes its own version of Fairfax's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Fairfax’s own scale
6 of the readings below were taken at Fairfax's own scale — its own ~178-day season between 28°F freezes, the 194 acres it covers and 43 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Fairfax's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Fairfax's own 28°F hard-freeze dates, about Apr 21 and Oct 16 and the ~178-day span between themNOAA 1991–2020 Climate Normals
- 43 documented contamination sites on the federal record near Fairfax, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Fairfax's boundary and the 194 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~178-day seasonGrowable Ground crop-matching engine
- The ecoregion at Fairfax's own centroid, the Northwestern Glaciated PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Fairfax's 194 acres read through its county's SSURGO summaryfrom Gregory County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Gregory County
- The growing challenges every South Dakota grower plans around — written at state scale, so they stay on the state guidefrom South Dakota
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Gregory County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Fairfax's 194 acreswhy one lot differs from the next →
- Which side of Fairfax you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 194 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Fairfax-wide figureread your own land →
More in South Dakota
Wider growing context
What grows across South DakotaFairfax sits outside our named growing regions, so South Dakota as a whole is its closest context here.
Nearby growing guides