Rock County, in Nebraska, sits in USDA hardiness zone 5a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
These conditions suit cabbage, cranberry, lavender, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Rock County lies within the Nebraska Sandhills — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Rock County holds more than one microclimate.
Soils and elevations shift across Rock 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 Rock County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Rock County — the short answer
Rock County, Nebraska: USDA zone 5a, about 174 days between hard freezes, across 645K acres.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 24
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 15
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~174
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 645K 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 5a is Rock County's average, not your lot's — a low corner or a tree line moves it. Against Rock County's 174-day season, see what your own ground reads.
Heat in Rock County
Across a year, Rock County accumulates about 2,583 growing degree days above 50°F, about 257 fewer than the middle Nebraska county — ahead of 17 of Nebraska’s 93 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 Rock County
Across Rock County, the ground is predominantly Entisols, where Valentine, Els, and Tryon are the most extensive named soil series. The soil is generally excessively drained with a fine sand surface. Topsoil pH runs about 6.5–6.7, neutral. Rainfall drains through hydrologic group A soils.
Soil order
Entisols
Drainage
Excessively drained
Hydric soils
11%
Soil still varies lot by lot — soil types explained.
How the ground varies across Rock County
The USDA soil survey maps 58% of Rock County as excessively drained — but another 41% drains differently: 22% somewhat poorly drained, 6% poorly drained.
Valentine is the most extensive named soil at 52% of mapped acres, then Els (17%) and Tryon (6%).
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 Rock County
Each reading below is measured for Rock 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 Rock County are excessively drained, in hydrologic group A — 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 Rock County runs about pH 6.5–6.7, 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
MeasuredRock County runs about 174 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
MeasuredRock County sits in USDA hardiness zone 5a.
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 County is in
Rock County spans 2 EPA Level III ecoregions — Nebraska Sand Hills (93%) and Northwestern Great Plains (7%). 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 Rock County
We scored all 1,086 plants against Rock County's own USDA zone 5a and its own 174-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 Nebraska profile.
Is it too late to plant in Rock County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 27; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 24 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 15 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
What gets applied to farmland in Rock County
USGS estimates 45,711 lb of Glyphosate on Rock County farmland in 2019, its largest by weight, ahead of Acetochlor (17,916 lb) and Atrazine (8,759 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 Rock County — and how to grow with it.
We checked the federal record across Rock County — 24 documented sites across 4 of the 9 source types we track.
The most significant on record: 1 concentrated animal feeding operation. Large-scale animal operations that can contaminate soil and groundwater with nitrates and pathogens.
The federal record across Rock County is light. Growing food here starts from a strong position — a quick pass over the map tells you whether any recorded site sits near your land, and if one does, that's information to plant with, not a reason to stop.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Rock County
Closest first, across Rock County. Listing isn't leaking, and distance isn't exposure.
- 28N 17W 9BD 1Nitrate · 6.0 mi
- 29N 19W33AC 1Nitrate · 7.3 mi
- 29N 17W 4BBCB1Nitrate · 9.9 mi
- ROCK COUNTY HOSPITALUnderground Storage Tanks · 13.8 mi
- RK CATTLE COMPANYCAFO · 14.0 mi
- SCOTTs PLACEUnderground Storage Tanks · 14.0 mi
- SUNNY'S LLCBrownfields · 14.6 mi
- KELLEY SERVICEUnderground Storage Tanks · 15.0 mi
- 30N 20W27DCCC1Nitrate · 15.0 mi
- NORTHERN PLAINS SUPPLY INC.Brownfields · 15.1 mi
- KMNE TV CHANNEL 7Underground Storage Tanks · 15.2 mi
- 30N 20W28DAAA1Nitrate · 15.8 mi
4 more sites are on the record inside the same radius. See them on the map
Measured from Rock 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 Rock County.
Sources Checked
across Rock County
Severity Distribution
across Rock County
Highest-Severity Sites
Know Before You Grow
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
Check your specific parcel in Rock 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 Rock County average
Your land is one point inside Rock County
Everything above resolves to Rock County as a whole — one PHZM band and one county frost record, read across 645K 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 Rock County Average
Rock County Average
- ●USDA Zones 5a, averaged across Rock County
- ●One soil character for all of Rock County
- ●Frost dates read at Rock County's scale: Apr 24 to Oct 15
YOUR Parcel
- ✓Your exact zone, not Rock County's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Rock County
Pull a site-specific report for your exact address in Rock County, Nebraska — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Rock County averages can't show:
We read public map data around Rock County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Rock County average
How we know this about Rock 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 Rock County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Rock County
When does frost risk typically end in Rock County?
The last hard freeze (28°F) in Rock County typically lands around Apr 24, 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 15.
How long is the growing season in Rock County?
Measured between 28°F hard freezes, Rock County sees about 174 frost-free days — roughly Apr 24 through Oct 15, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 15 to Oct 1, about 139 days.
Is the soil safe to grow vegetables in Rock County?
The federal record around Rock County is light — 24 documented sites across the 9 federal source types we checked, mostly Nitrate entries (16), the nearest Nitrate record about 6.0 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.
Everything above is measured at Rock County's scale — its 5a band and its 174-day season. Your yard writes its own version of Rock 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 Nebraska's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Rock County’s own scale
8 of the readings below were taken at Rock County's own scale — its own ~174-day span between 28°F freezes, the 3 most extensive soil series mapped here and 24 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Rock County's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Rock County's own 28°F hard-freeze dates and its ~174-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Rock CountyUSDA NRCS SSURGO
- 24 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 6.0 miles outFederal environmental registers
- Rock County's boundary and the 645,306 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~174-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Rock County spans, Nebraska Sand Hills the largestUS EPA Level III Ecoregions
- Which agricultural compounds go onto Rock County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Nebraska grower plans around — written at state scale, so they stay on the state guidefrom Nebraska
What this page can’t tell you
- How the season shifts across Rock County — the ~174 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 Rock County's 645,306 acreswhy one lot differs from the next →
- Which of those 24 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 Rock Countyread your own land →