Colby, Wisconsin, sits in USDA hardiness zone 4b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Growers here do well with cabbage, cranberry, turkish rocket, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Colby, 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 Colby 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 Colby — soil, climate, flood, and parcel records. How we handle your address.
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Colby — the short answer
Colby, Wisconsin: USDA zone 4b, about 168 days between hard freezes, across 1K acres of city.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 12
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~168
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City 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 Colby's average, not your lot's — a low corner or a tree line moves it. Against Colby's 168-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Colby
Each reading below is measured for Colby itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredColby runs about 168 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
MeasuredColby 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 Colby is in
Colby sits in the North Central Hardwood Forests — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Colby's own centroid rather than borrowed from Clark County.
What Grows in Colby
Every plant below cleared Colby's own zone 4b and its 168-day season. Each card opens that plant's Wisconsin profile. How we score.
Is it too late to plant in Colby?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Mar 30; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 12 — 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's on the federal record near Colby
Closest first, within ~10 miles of Colby. Listing isn't leaking, and distance isn't exposure.
- KWIK TRIP #362Underground Storage Tanks · 400 ft
- DIESEL TRUCK SERVICEBrownfields · 600 ft
- Town Of ColbyUnderground Storage Tanks · 650 ft
- GEORGE RANKELUnderground Storage Tanks · 650 ft
- HARMONY COOPUnderground Storage Tanks · 650 ft
- Hugh McgeeUnderground Storage Tanks · 650 ft
- Cherokee Garage IncUnderground Storage Tanks · 650 ft
- ROCKY CREEK FARMUnderground Storage Tanks · 650 ft
- RALPH WILLUnderground Storage Tanks · 650 ft
- CITY OF COLBY OLD GARAGEUnderground Storage Tanks · 1100 ft
- GTE - COLBYUnderground Storage Tanks · 1600 ft
- Buy Rite AutoUnderground Storage Tanks · 2000 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Colby'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 Colby.
Sources Checked
within ~10 miles of Colby
Severity Distribution
within ~10 miles of Colby
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Colby, two things run higher than the national average within ~10 miles of Colby — CAFO (4 sites) and Toxics Release Inventory (11 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Colby
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 Colby average
Your land is one point inside Colby
Everything above resolves to Colby 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 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 Colby Average
Colby Average
- ●USDA Zones 4b, averaged across Colby
- ●One soil character for all of Colby
- ●Frost dates read at Colby's scale: Apr 27 to Oct 12
YOUR Parcel
- ✓Your exact zone, not Colby's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Colby
Pull a site-specific report for your exact address in Colby, Wisconsin — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Colby averages can't show:
We read public map data around Colby — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Colby average
How we know this about Colby
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 Colby’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 Colby
When does frost risk typically end in Colby?
The last hard freeze (28°F) in Colby typically lands around Apr 27, 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 18.
When is the first frost in Colby?
The first hard freeze (28°F) in Colby typically arrives around Oct 12, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 28, so the watching starts about Sep 12 — about 168 days after the spring freeze cleared.
How long is the growing season in Colby?
Measured between 28°F hard freezes, Colby sees about 168 frost-free days — roughly Apr 27 through Oct 12, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 18 to Sep 28, about 133 days.
Is the soil safe to grow vegetables in Colby?
The federal record around Colby is a meaningful one — 161 documented sites, mostly Underground Storage Tanks entries (104), the nearest Underground Storage Tanks record under a tenth of a mile 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 Colby?
From about Sep 12 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 12 (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 12. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Colby's scale — its 4b band and its 168-day season. Your yard writes its own version of Colby'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 Colby’s own scale
6 of the readings below were taken at Colby's own scale — its own ~168-day season between 28°F freezes, the 1,048 acres it covers and 161 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Colby's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Colby's own 28°F hard-freeze dates, about Apr 27 and Oct 12 and the ~168-day span between themNOAA 1991–2020 Climate Normals
- 161 documented contamination sites on the federal record near Colby, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Colby's boundary and the 1,048 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~168-day seasonGrowable Ground crop-matching engine
- The ecoregion at Colby's own centroid, the North Central Hardwood ForestsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Colby's 1,048 acres read through its county's SSURGO summaryfrom Clark County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Clark County
- The growing challenges every Wisconsin grower plans around — written at state scale, so they stay on the state guidefrom Wisconsin
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Clark County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Colby's 1,048 acreswhy one lot differs from the next →
- Which side of Colby you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,048 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile 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 Colby-wide figureread your own land →
More in Wisconsin
Wider growing context
What grows across WisconsinColby sits outside our named growing regions, so Wisconsin as a whole is its closest context here.
Nearby growing guides