Richfield, Idaho, sits in USDA hardiness zone 6a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Reliable performers under these conditions include cabbage, blackberry, california poppy, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Richfield, 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 Richfield 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 Richfield — soil, climate, flood, and parcel records. How we handle your address.
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Richfield — the short answer
Richfield, Idaho: USDA zone 6a, about 159 days between hard freezes, across 420 acres of city.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 3
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 9
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~159
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 420 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 6a is Richfield's average, not your lot's — a low corner or a tree line moves it. Against Richfield's 159-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Richfield
Each reading below is measured for Richfield itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRichfield runs about 159 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
MeasuredRichfield sits in USDA hardiness zone 6a.
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 Richfield is in
Richfield sits in the Snake River Plain — EPA Level III, inside the wider North American Deserts. That is read at Richfield's own centroid rather than borrowed from Lincoln County.
What Grows in Richfield
Every plant below cleared Richfield's own zone 6a and its 159-day season. Each card opens that plant's Idaho profile. How we score.
Is it too late to plant in Richfield?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 5; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 3 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 9 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
What's on the federal record near Richfield
Closest first, within ~10 miles of Richfield. Listing isn't leaking, and distance isn't exposure.
- RICHFIELD HIGHWAY DISTUnderground Storage Tanks · 700 ft
- 04S 19E 26AAD1Nitrate · 750 ft
- Chevron RichfieldUnderground Storage Tanks · 1000 ft
- PAULSON MOTOR SERVICEUnderground Storage Tanks · 1100 ft
- Paulson SinclairUnderground Storage Tanks · 1300 ft
- CHARLES PERRYUnderground Storage Tanks · 1300 ft
- GLANBIA FOODS RICHFIELDToxics Release Inventory · 2100 ft
- 04S 20E 19CBC1Nitrate · 1.2 mi
- 04S 19E 34ABB3Nitrate · 1.6 mi
- 04S 20E 18BBB1Nitrate · 2.5 mi
- PAULSON GAS AND OILUnderground Storage Tanks · 2.7 mi
- AVONMORE WEST INCUnderground Storage Tanks · 2.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Richfield'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 Richfield.
Total Sites
29
within ~10 miles of Richfield
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Richfield
Severity Distribution
within ~10 miles of Richfield
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Richfield, Nitrate runs higher than the national average — 20 sites within ~10 miles of Richfield. 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 Richfield
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 Richfield average
Your land is one point inside Richfield
Everything above resolves to Richfield as a whole — one PHZM band and one 28°F frost record, read across 420 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 city 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 Richfield Average
Richfield Average
- ●USDA Zones 6a, averaged across Richfield
- ●One soil character for all of Richfield
- ●Frost dates read at Richfield's scale: May 3 to Oct 9
YOUR Parcel
- ✓Your exact zone, not Richfield's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Richfield
Pull a site-specific report for your exact address in Richfield, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Richfield averages can't show:
We read public map data around Richfield — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Richfield average
How we know this about Richfield
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Richfield’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 city grain anywhere on this page — there is no city-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 Richfield
When does frost risk typically end in Richfield?
The last hard freeze (28°F) in Richfield typically lands around May 3, 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 24.
When is the first frost in Richfield?
The first hard freeze (28°F) in Richfield typically arrives around Oct 9, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 25, so the watching starts about Sep 9 — about 159 days after the spring freeze cleared.
How long is the growing season in Richfield?
Measured between 28°F hard freezes, Richfield sees about 159 frost-free days — roughly May 3 through Oct 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 24 to Sep 25, about 124 days.
Is the soil safe to grow vegetables in Richfield?
The federal record around Richfield is a meaningful one — 29 documented sites, mostly Nitrate entries (20), the nearest Underground Storage Tanks record about 0.1 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.
How do I protect my plants from frost in Richfield?
From about Sep 9 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 9 (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 9. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Richfield's scale — its 6a band and its 159-day season. Your yard writes its own version of Richfield'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 Richfield’s own scale
6 of the readings below were taken at Richfield's own scale — its own ~159-day season between 28°F freezes, the 420 acres it covers and 29 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Richfield's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Richfield's own 28°F hard-freeze dates, about May 3 and Oct 9 and the ~159-day span between themNOAA 1991–2020 Climate Normals
- 29 documented contamination sites on the federal record near Richfield, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Richfield's boundary and the 420 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~159-day seasonGrowable Ground crop-matching engine
- The ecoregion at Richfield's own centroid, the Snake River PlainUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Richfield's 420 acres read through its county's SSURGO summaryfrom Lincoln County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Lincoln County
- The growing challenges every Idaho grower plans around — written at state scale, so they stay on the state guidefrom Idaho
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Lincoln County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Richfield's 420 acreswhy one lot differs from the next →
- Which side of Richfield you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 420 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.1 miles 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 Richfield-wide figureread your own land →