Rock River, Wyoming, 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.
Among the crops suited to this profile: cabbage, cranberry, cilantro, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Even in Rock River, 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 Rock River 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 Rock River — soil, climate, flood, and parcel records. How we handle your address.
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Rock River — the short answer
Rock River, Wyoming: USDA zone 4b, about 137 days between hard freezes, across 1K acres of town.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 12
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 26
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~137
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 1K 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 Rock River's average, not your lot's — a low corner or a tree line moves it. Against Rock River's 137-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Rock River
Each reading below is measured for Rock River itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRock River runs about 137 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
MeasuredRock River 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 Rock River is in
Rock River sits in the Wyoming Basin — EPA Level III, inside the wider North American Deserts. That is read at Rock River's own centroid rather than borrowed from Albany County.
What Grows in Rock River
Every plant below cleared Rock River's own zone 4b and its 137-day season. Each card opens that plant's Wyoming profile. How we score.
Is it too late to plant in Rock River?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 14; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 12 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 26 — long-season crops need about 90 days of runway, quick greens only 30. When the window is tight, the fall moves are quick ones — baby greens, radishes, and garlic set for next season.
What's on the federal record near Rock River
Closest first, within ~10 miles of Rock River. Listing isn't leaking, and distance isn't exposure.
- RANCHERS SUPPLY INC.Brownfields · 0.5 mi
- ShopUnderground Storage Tanks · 0.6 mi
- Lee WhiteUnderground Storage Tanks · 0.8 mi
- Hostler's General StoreUnderground Storage Tanks · 0.9 mi
- ALBANY COUNTY ROAD & BRIDGEBrownfields · 0.9 mi
- Rock River Tool HouseUnderground Storage Tanks · 0.9 mi
- Rock River Relay StationUnderground Storage Tanks · 0.9 mi
- Jim DobsonUnderground Storage Tanks · 0.9 mi
- 20-076-29bda01Nitrate · 3.6 mi
- 21-077-27cb 01Nitrate · 4.4 mi
- 20-076-01ccc01Nitrate · 4.5 mi
- Doc's Western VillageUnderground Storage Tanks · 5.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Rock River'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 Rock River.
Sources Checked
within ~10 miles of Rock River
Severity Distribution
within ~10 miles of Rock River
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Rock River, Nitrate runs higher than the national average — 16 sites within ~10 miles of Rock River. 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 Rock River
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 Rock River average
Your land is one point inside Rock River
Everything above resolves to Rock River as a whole — one PHZM band and one 28°F frost record, read across 1K 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 Rock River Average
Rock River Average
- ●USDA Zones 4b, averaged across Rock River
- ●One soil character for all of Rock River
- ●Frost dates read at Rock River's scale: May 12 to Sep 26
YOUR Parcel
- ✓Your exact zone, not Rock River's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Rock River
Pull a site-specific report for your exact address in Rock River, Wyoming — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Rock River averages can't show:
We read public map data around Rock River — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Rock River average
How we know this about Rock River
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 Rock River’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 Rock River
When does frost risk typically end in Rock River?
The last hard freeze (28°F) in Rock River typically lands around May 12, 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 2.
When is the first frost in Rock River?
The first hard freeze (28°F) in Rock River typically arrives around Sep 26, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 12, so the watching starts about Aug 27 — about 137 days after the spring freeze cleared.
How long is the growing season in Rock River?
Measured between 28°F hard freezes, Rock River sees about 137 frost-free days — roughly May 12 through Sep 26, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 2 to Sep 12, about 102 days.
Is the soil safe to grow vegetables in Rock River?
The federal record around Rock River is light — 30 documented sites across the 9 federal source types we checked, mostly Nitrate entries (16), the nearest Brownfields record about 0.5 miles 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 gardeners stretch the season in Rock River?
With about 137 frost-free days between hard freezes, Rock River 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 165 to 193 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 12 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Rock River's scale — its 4b band and its 137-day season. Your yard writes its own version of Rock River'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 Rock River’s own scale
6 of the readings below were taken at Rock River's own scale — its own ~137-day season between 28°F freezes, the 1,489 acres it covers and 30 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Rock River's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Rock River's own 28°F hard-freeze dates, about May 12 and Sep 26 and the ~137-day span between themNOAA 1991–2020 Climate Normals
- 30 documented contamination sites on the federal record near Rock River, the closest Brownfields record about 0.5 miles out from the town centreFederal environmental registers
- Rock River's boundary and the 1,489 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~137-day seasonGrowable Ground crop-matching engine
- The ecoregion at Rock River's own centroid, the Wyoming BasinUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Rock River's 1,489 acres read through its county's SSURGO summaryfrom Albany County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Albany County
- The growing challenges every Wyoming grower plans around — written at state scale, so they stay on the state guidefrom Wyoming
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Albany County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Rock River's 1,489 acreswhy one lot differs from the next →
- Which side of Rock River you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,489 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.5 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 Rock River-wide figureread your own land →
More in Wyoming
Wider growing context
What grows across WyomingRock River sits outside our named growing regions, so Wyoming as a whole is its closest context here.
Nearby growing guides