Knowlton, Wisconsin, sits in USDA hardiness zone 5a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Reliable performers under these conditions include cabbage, cranberry, lavender, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Knowlton, 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 Knowlton 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 Knowlton — soil, climate, flood, and parcel records. How we handle your address.
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Knowlton — the short answer
Knowlton, Wisconsin: USDA zone 5a, about 176 days between hard freezes, across 640 acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~176
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 640 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 5a is Knowlton's average, not your lot's — a low corner or a tree line moves it. Against Knowlton's 176-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Knowlton
Each reading below is measured for Knowlton itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredKnowlton runs about 176 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
MeasuredKnowlton 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 Knowlton is in
Knowlton sits in the North Central Hardwood Forests — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Knowlton's own centroid rather than borrowed from Marathon County.
What Grows in Knowlton
Every plant below cleared Knowlton's own zone 5a and its 176-day season. Each card opens that plant's Wisconsin profile. How we score.
Is it too late to plant in Knowlton?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Mar 26; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 23 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 16 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
What's on the federal record near Knowlton
Closest first, within ~10 miles of Knowlton. Listing isn't leaking, and distance isn't exposure.
- ALS SERV STATIONUnderground Storage Tanks · 550 ft
- LLOYD SCHEIDE - SALOON DU BAYUnderground Storage Tanks · 600 ft
- Mullins Cheese IncUnderground Storage Tanks · 700 ft
- MULLINS CHEESE FACTORY-300Toxics Release Inventory · 700 ft
- ST FRANCIS XAIVER CHURCHUnderground Storage Tanks · 1600 ft
- TAYLOR WOODSHAVINGS COUnderground Storage Tanks · 0.8 mi
- CAMP DU BAY SHORESUnderground Storage Tanks · 0.9 mi
- Town Of KnowltonUnderground Storage Tanks · 1.0 mi
- RONALD MEYERUnderground Storage Tanks · 1.0 mi
- SCHELLIN MARINEUnderground Storage Tanks · 2.1 mi
- WESTON DISPOSAL SITE NO. 3 EXPANSION (LEGNER)Toxics Release Inventory · 2.4 mi
- SUNSHINE INVESTMENTSUnderground Storage Tanks · 2.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Knowlton'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 Knowlton.
Total Sites
189
within ~10 miles of Knowlton
Risk Level
Moderate
Highest-severity
8 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Knowlton
Severity Distribution
within ~10 miles of Knowlton
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Knowlton, Underground Storage Tanks runs higher than the national average — 138 sites within ~10 miles of Knowlton. That's not a problem with your land — it's information about 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 Knowlton
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 Knowlton average
Your land is one point inside Knowlton
Everything above resolves to Knowlton as a whole — one PHZM band and one 28°F frost record, read across 640 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 Knowlton Average
Knowlton Average
- ●USDA Zones 5a, averaged across Knowlton
- ●One soil character for all of Knowlton
- ●Frost dates read at Knowlton's scale: Apr 23 to Oct 16
YOUR Parcel
- ✓Your exact zone, not Knowlton's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Knowlton
Pull a site-specific report for your exact address in Knowlton, Wisconsin — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Knowlton averages can't show:
We read public map data around Knowlton — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Knowlton average
How we know this about Knowlton
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 Knowlton’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 Knowlton
When does frost risk typically end in Knowlton?
The last hard freeze (28°F) in Knowlton typically lands around Apr 23, 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 14.
When is the first frost in Knowlton?
The first hard freeze (28°F) in Knowlton typically arrives around Oct 16, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 2, so the watching starts about Sep 16 — about 176 days after the spring freeze cleared.
How long is the growing season in Knowlton?
Measured between 28°F hard freezes, Knowlton sees about 176 frost-free days — roughly Apr 23 through Oct 16, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 14 to Oct 2, about 141 days.
Is the soil safe to grow vegetables in Knowlton?
The federal record around Knowlton shows 189 documented sites, mostly Underground Storage Tanks entries (138), the nearest Underground Storage Tanks record about 0.1 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Knowlton?
From about Sep 16 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 16 (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 16. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Knowlton's scale — its 5a band and its 176-day season. Your yard writes its own version of Knowlton'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 Knowlton’s own scale
6 of the readings below were taken at Knowlton's own scale — its own ~176-day season between 28°F freezes, the 640 acres it covers and 189 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Knowlton's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Knowlton's own 28°F hard-freeze dates, about Apr 23 and Oct 16 and the ~176-day span between themNOAA 1991–2020 Climate Normals
- 189 documented contamination sites on the federal record near Knowlton, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Knowlton's boundary and the 640 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~176-day seasonGrowable Ground crop-matching engine
- The ecoregion at Knowlton'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 Knowlton's 640 acres read through its county's SSURGO summaryfrom Marathon County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Marathon 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 Marathon County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Knowlton's 640 acreswhy one lot differs from the next →
- Which side of Knowlton you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 640 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.1 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 Knowlton-wide figureread your own land →
More in Wisconsin
Wider growing context
What grows across WisconsinKnowlton sits outside our named growing regions, so Wisconsin as a whole is its closest context here.
Nearby growing guides