Bonneville County, in Idaho, sits in USDA hardiness zone 5b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
A short list that earns its place here — cabbage, cranberry, lavender, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Bonneville County lies within the Eastern Idaho (Upper Snake River Valley) — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Bonneville County holds more than one microclimate.
Soils and elevations shift across Bonneville 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 Bonneville County — soil, climate, flood, and parcel records. How we handle your address.
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Bonneville County — the short answer
Bonneville County, Idaho: USDA zone 5b, about 134 days between hard freezes, across 1.2M acres.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 18
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Sep 29
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~134
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 1.2M 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 5b is Bonneville County's average, not your lot's — a low corner or a tree line moves it. Against Bonneville County's 134-day season, see what your own ground reads.
Heat in Bonneville County
Across a year, Bonneville County accumulates about 1,187 growing degree days above 50°F, about 304 fewer than the middle Idaho county — ahead of 14 of Idaho’s 44 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 Bonneville County
Across Bonneville County, the ground is predominantly Mollisols, where Pancheri, Ririe, and Edgway are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 6.7–7.6, neutral. Rainfall drains through hydrologic group B soils.
Soil order
Mollisols
Drainage
Well drained
Hydric soils
2%
Soil still varies lot by lot — soil types explained.
How the ground varies across Bonneville County
The USDA soil survey maps 85% of Bonneville County as well drained — but another 8% drains differently: 2% somewhat poorly drained, 2% moderately well drained.
Pancheri is the most extensive named soil at 12% of mapped acres, then Ririe (8%) and Edgway (3%).
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 Bonneville County
Each reading below is measured for Bonneville 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 Bonneville County are well drained, in hydrologic group B — 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 Bonneville County runs about pH 6.7–7.6, 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
MeasuredBonneville County runs about 134 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredBonneville County sits in USDA hardiness zone 5b.
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 Bonneville County is in
Bonneville County spans 2 EPA Level III ecoregions — Middle Rockies (60%) and Snake River Plain (38%). 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 Bonneville County
We scored all 1,086 plants against Bonneville County's own USDA zone 5b and its own 134-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 Idaho profile.
Is it too late to plant in Bonneville County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Apr 20; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 18 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 29 — long-season crops need about 90 days of runway, quick greens only 30. In a season this compact, fast finishers and cold-hardy greens do the late work, and garlic tucked in before the freeze repays you next summer.
What gets applied to farmland in Bonneville County
USGS estimates 56,900 lb of Glyphosate on Bonneville County farmland in 2019, its largest by weight, ahead of 2,4-d (16,832 lb) and Metolachlor-s (16,201 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 Bonneville County — and how to grow with it.
We checked the federal record across Bonneville County — 628 documented sites across 8 of the 9 source types we track.
The most significant on record: 2 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 Bonneville 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 Bonneville County
Closest first, across Bonneville County. Listing isn't leaking, and distance isn't exposure.
- 01N 41E 06DAD1Nitrate · 4.0 mi
- TEX CREEK WILDLIFE MGMT A REAUnderground Storage Tanks · 6.4 mi
- 01N 39E 36AAC1Nitrate · 9.5 mi
- 01S 40E 28CDC1Nitrate · 10.4 mi
- 02N 43E 30CBD1Nitrate · 10.4 mi
- HARVY COLLINS/BONE STOREUnderground Storage Tanks · 10.5 mi
- 02N 42E 05AAD2Nitrate · 10.7 mi
- US DA FS SNAKE RIVER WK CTRSuperfund · 10.8 mi
- UCON PRODUCE INC 2Underground Storage Tanks · 11.0 mi
- USBR RIRIE DAM FIELD STATIONUnderground Storage Tanks · 11.0 mi
- ID PACIFIC CORPUnderground Storage Tanks · 11.0 mi
- PRO-IDAUnderground Storage Tanks · 11.0 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Bonneville 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 Bonneville County.
Total Sites
628
across Bonneville County
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
across Bonneville County
Severity Distribution
across Bonneville County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Bonneville County, Underground Storage Tanks runs higher than the national average — 392 sites across Bonneville County. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Bonneville 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 Bonneville County average
Your land is one point inside Bonneville County
Everything above resolves to Bonneville County as a whole — one PHZM band and one county frost record, read across 1.2M 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 Bonneville County Average
Bonneville County Average
- ●USDA Zones 5b, averaged across Bonneville County
- ●One soil character for all of Bonneville County
- ●Frost dates read at Bonneville County's scale: May 18 to Sep 29
YOUR Parcel
- ✓Your exact zone, not Bonneville County's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Bonneville County
Pull a site-specific report for your exact address in Bonneville County, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Bonneville County averages can't show:
We read public map data around Bonneville County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Bonneville County average
How we know this about Bonneville 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 Bonneville County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Bonneville County
When does frost risk typically end in Bonneville County?
The last hard freeze (28°F) in Bonneville County typically lands around May 18, 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 Jun 8.
How long is the growing season in Bonneville County?
Measured between 28°F hard freezes, Bonneville County sees about 134 frost-free days — roughly May 18 through Sep 29, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 8 to Sep 15, about 99 days.
Is the soil safe to grow vegetables in Bonneville County?
The federal record around Bonneville County is a meaningful one — 628 documented sites, mostly Underground Storage Tanks entries (392), the nearest Nitrate record about 4.0 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 gardeners stretch the season in Bonneville County?
With about 134 frost-free days between hard freezes, Bonneville County rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 162 to 190 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 18 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Bonneville County's scale — its 5b band and its 134-day season. Your yard writes its own version of Bonneville 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 Idaho's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Bonneville County’s own scale
8 of the readings below were taken at Bonneville County's own scale — its own ~134-day span between 28°F freezes, the 3 most extensive soil series mapped here and 628 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Bonneville County's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Bonneville County's own 28°F hard-freeze dates and its ~134-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Bonneville CountyUSDA NRCS SSURGO
- 628 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 4.0 miles outFederal environmental registers
- Bonneville County's boundary and the 1,194,214 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~134-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Bonneville County spans, Middle Rockies the largestUS EPA Level III Ecoregions
- Which agricultural compounds go onto Bonneville County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Idaho grower plans around — written at state scale, so they stay on the state guidefrom Idaho
What this page can’t tell you
- How the season shifts across Bonneville County — the ~134 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 Bonneville County's 1,194,214 acreswhy one lot differs from the next →
- Which of those 628 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 Bonneville Countyread your own land →