Agar, South Dakota, sits in USDA hardiness zone 4b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
The conditions favor cabbage, cranberry, turkish rocket, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Even in Agar, 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 Agar 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 Agar — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Agar — the short answer
Agar, South Dakota: USDA zone 4b, about 168 days between hard freezes, across 131 acres of town.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 12
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~168
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 131 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 4b is Agar's average, not your lot's — a low corner or a tree line moves it. Against Agar's 168-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Agar
Each reading below is measured for Agar itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredAgar runs about 168 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
MeasuredAgar sits in USDA hardiness zone 4b.
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 Agar is in
Agar sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Agar's own centroid rather than borrowed from Sully County.
What Grows in Agar
Every plant below cleared Agar's own zone 4b and its 168-day season. Each card opens that plant's South Dakota profile. How we score.
Is it too late to plant in Agar?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 30; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 12 — 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 Agar
Closest first, within ~10 miles of Agar. Listing isn't leaking, and distance isn't exposure.
- 116N77W23CDCD (2)Nitrate · 250 ft
- 116N77W23CDCDNitrate · 450 ft
- AGAR SCHOOL DISTRICT 58-1Brownfields · 500 ft
- 116N76W 8DDDDNitrate · 4.0 mi
- MYRON VETTERUnderground Storage Tanks · 6.9 mi
- MID-DAKOTA RURAL WATERPFAS · 7.4 mi
- 114N77W 2DCA2Nitrate · 8.9 mi
- 114N77W 2DCANitrate · 8.9 mi
- SULLY COUNTYUnderground Storage Tanks · 8.9 mi
- STAHL SERVICEUnderground Storage Tanks · 9.0 mi
- STEWERT & SONS INCUnderground Storage Tanks · 9.1 mi
- SHOUP OILUnderground Storage Tanks · 9.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Agar'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 Agar.
Sources Checked
within ~10 miles of Agar
Severity Distribution
within ~10 miles of Agar
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Agar, Nitrate runs higher than the national average — 14 sites within ~10 miles of Agar. 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 Agar
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 Agar average
Your land is one point inside Agar
Everything above resolves to Agar as a whole — one PHZM band and one 28°F frost record, read across 131 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 Agar Average
Agar Average
- ●USDA Zones 4b, averaged across Agar
- ●One soil character for all of Agar
- ●Frost dates read at Agar's scale: Apr 27 to Oct 12
YOUR Parcel
- ✓Your exact zone, not Agar's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Agar
Pull a site-specific report for your exact address in Agar, South Dakota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Agar averages can't show:
We read public map data around Agar — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Agar average
How we know this about Agar
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 Agar’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 Agar
When does frost risk typically end in Agar?
The last hard freeze (28°F) in Agar typically lands around Apr 27, 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 18.
When is the first frost in Agar?
The first hard freeze (28°F) in Agar typically arrives around Oct 12, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 28, so the watching starts about Sep 12 — about 168 days after the spring freeze cleared.
How long is the growing season in Agar?
Measured between 28°F hard freezes, Agar sees about 168 frost-free days — roughly Apr 27 through Oct 12, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 18 to Sep 28, about 133 days.
Is the soil safe to grow vegetables in Agar?
The federal record around Agar shows 28 documented sites, mostly Nitrate entries (14), the nearest Nitrate record under a tenth of a mile 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.
How do I protect my plants from frost in Agar?
From about Sep 12 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 12 (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 12. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Agar's scale — its 4b band and its 168-day season. Your yard writes its own version of Agar'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 Agar’s own scale
6 of the readings below were taken at Agar's own scale — its own ~168-day season between 28°F freezes, the 131 acres it covers and 28 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Agar's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Agar's own 28°F hard-freeze dates, about Apr 27 and Oct 12 and the ~168-day span between themNOAA 1991–2020 Climate Normals
- 28 documented contamination sites on the federal record near Agar, the closest Nitrate record under a tenth of a mile out from the town centreFederal environmental registers
- Agar's boundary and the 131 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~168-day seasonGrowable Ground crop-matching engine
- The ecoregion at Agar's own centroid, the Northwestern Glaciated PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Agar's 131 acres read through its county's SSURGO summaryfrom Sully County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Sully 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 Sully County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Agar's 131 acreswhy one lot differs from the next →
- Which side of Agar you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 131 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate 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 Agar-wide figureread your own land →
More in South Dakota
Wider growing context
What grows across South DakotaAgar sits outside our named growing regions, so South Dakota as a whole is its closest context here.
Nearby growing guides