The Star Valley spans USDA hardiness zones 4b-5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
A high mountain valley on the Idaho line — twelve towns of 4b-5a hay-and-garden ground with a 106-128-day frost window; short, bright, honest mountain gardening in the valley the Mormon settlers called the Star of all valleys. Well-matched crops include potato, rhubarb, chokecherry, and indian paintbrush, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
The Star Valley spans Wyoming.
Your yard isn't all of the Star Valley.
The Star Valley spans USDA zones 4b-5a, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Star Valley — soil, climate, flood, and parcel records. How we handle your address.
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The Star Valley — the short answer
The Star Valley: USDA zones 4b-5a, 106–128 frost-free days, in Wyoming.
- USDA zones
- 4b-5a
- USDA PHZM 2023, aggregated over the footprint
- Frost-free season
- 106–128 days
- NOAA Regional Climate Centers ACIS, 1991-2020
- Towns
- 12
- US Census TIGER/Line 2025
- Region type
- Town cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. Where a region publishes no measured season, no season figure is shown.
Hardiness Zone Range
What Grows in the Star Valley
Plants matched to the Star Valley's USDA zones 4b-5a, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the Star Valley
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the Star Valley’s USDA zones 4b-5a — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground around the Star Valley
The USDA soil survey maps this ground county by county. These are those records weighted by land area across the county containing the Star Valley — the ground the Star Valley sits in, read at the only grain the survey publishes.
In the county containing the Star Valley, the ground is predominantly Mollisols, at 40% of mapped acres, followed by Alfisols (27%), Inceptisols (14%) and Aridisols (13%). Seven soil orders appear in that record, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Langspring, Mantlemine, and Quakenasp.
92% of those acres are well drained, and another 2% poorly drained, 2% somewhat excessively drained. Topsoil pH runs 6.3–7.8 in that county’s own record.
Soil order
Mollisols
Drainage
Well drained
Topsoil pH
6.3–7.8
Hydric soils
1%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Star Valley
The soil survey reads this ground county by county, and the readings above are the record for the county containing the Star Valley. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records92% of the mapped acres across the county containing the Star Valley are well drained — ground that drains quickly. The survey maps this ground county-wide, so it describes the setting the Star Valley sits in rather than the valley floor alone.
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
From county recordsTopsoil across the county containing the Star Valley runs pH 6.3–7.8 — near neutral in the one record covering it.
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
Safe to Grow Here?
What the federal record shows across the Star Valley — and how to grow with it.
Across Lincoln County, which contains the Star Valley, the federal record holds 383 documented sites, mostly Nitrate (178), Underground Storage Tanks (138) and Brownfields (39).
That is the containing county's count — this region is a smaller piece of that ground, so it is context, not a reading of any one lot. Open the map outlined to the Star Valley to see which records sit where you actually grow.
Sources Checked
Summed across the county containing the Star Valley
A note from Gnorman
What an experienced grower watches for around here
In and around the Star Valley, Nitrate runs higher than the national average — 178 sites across the county containing the Star Valley. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Star Valley
Everything above resolves to the Star Valley as a whole — a footprint spanning USDA zones 4b-5a. Your parcel sits in exactly one of them. 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 region 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 regional average.
Your Lot vs the Star Valley Average
Star Valley Average
- ●USDA Zones 4b-5a, averaged across Star Valley
- ●One soil character for all of Star Valley
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Star Valley's 4b-5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Star Valley
Pull a site-specific report for your exact address in the Star Valley — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Star Valley averages can't show:
We read public map data around The Star Valley — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Star Valley average
How we know this about the Star Valley
The boundary: the region's own towns — a footprint finer than any county, because the county average would misread this microclimate. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the towns inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the Star Valley
What hardiness zone is the Star Valley?
The Star Valley spans USDA hardiness zones 4b-5a, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's own towns. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the Star Valley?
Measured between 28°F hard freezes, the Star Valley's towns mostly run 110 to 120 frost-free days, median 114 (NOAA Regional Climate Centers ACIS, 1991–2020, over 12 member towns). That 10-day spread is the honest read — no single season describes 12 towns, and each town guide below carries its own.
When does frost risk end in the Star Valley?
Across the Star Valley, the middle half of member towns see their last 28°F hard freeze between May 22 and May 27 (median May 26), and their first fall freeze between Sep 14 and Sep 19. Those are hard freezes, not the last light frost: tender transplants wait for about Jun 16, and elevation decides which end of a 5-day spread you garden in.
What grows well in the Star Valley?
The Star Valley's conditions suit plants such as Potato, Rhubarb, Chokecherry, Indian Paintbrush, Cottonwood. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the Star Valley defined?
The Star Valley is a true microclimate — smaller than the county that contains it, with a growing reality of its own. So this page is built from the region's own 12 towns, each carrying its own hardiness zone and frost record, rather than from a county average measured somewhere else.
Which states does the Star Valley cover?
The Star Valley spans Wyoming. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
High Plains, Bighorn Basin, Jackson Hole & Teton Valley, and Wind River Basin (Lander–Riverton) share at least one state with the Star Valley. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the Star Valley’s own scale
6 of the readings below were taken at the Star Valley's own scale — the zone 4b-5a band across its footprint, a median 114-day season across its 12 towns and 383 documented federal contamination records across its one county, 383 of them in Lincoln County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 4b-5a aggregated across all 12 towns in the footprintUSDA PHZM 2023
- The boundary itself — the 12 towns this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 12 towns run 110 to 120 frost-free days, median 114NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 383 documented federal contamination records across its one county, 383 of them in Lincoln County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 40% Mollisols, topsoil pH 6.3–7.8, area-weighted across its one mapped countyUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 4b-5afrom Wyoming
What this page can’t tell you
- Which end of the 10-day range your ground sits at — 110 days at one extreme, 120 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the Star Valley
State growing guides
Towns in this region
The county containing this region
Other growing regions across Wyoming
A semi-arid shortgrass tableland of deep soils and big sky, where wind, low rainfall, and irrigation shape dryland wheat, sorghum, and resilient gardens.
Wyoming's warmest, longest-season ground sits in a rain-shadow desert, not on a mountainside. The Bighorn Basin runs 117–166 frost-free days in USDA zones 4b–5a at about 4,000–4,500 ft — the irrigated basin floor holds the long end of that range and the mountain rim the short one, and the middle of it still runs 30 to 90 days longer than the ranges that wall it in. What grows here is a fundamentally irrigated story: Bighorn- and Shoshone-river water turns a semi-arid valley into Wyoming's commercial sugar-beet, dry-bean (pinto), malting-barley and alfalfa country. Plan for cold high-desert swings and irrigation, not high-plains dryland.
Two high valleys astride the Tetons where summer frost is never truly off the table — a 4a-6a band and a roughly 99-131-day window that make cold-hardy, fast, and season-extended the entire playbook.
Lander and Riverton's sheltered basin — a banana belt by Wyoming standards, where the Wind River's 4b-5a floor squeezes out a 147-171-day season the surrounding high country cannot match.