Houlton, Wisconsin, sits in USDA hardiness zone 5a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Growers here do well with cabbage, cranberry, lavender, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Houlton, 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 Houlton 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 Houlton — soil, climate, flood, and parcel records. How we handle your address.
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Houlton — the short answer
Houlton, Wisconsin: USDA zone 5a, about 192 days between hard freezes, across 936 acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 25
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~192
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 936 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 Houlton's average, not your lot's — a low corner or a tree line moves it. Against Houlton's 192-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Houlton
Each reading below is measured for Houlton itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHoulton runs about 192 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
MeasuredHoulton 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 Houlton is in
Houlton sits in the North Central Hardwood Forests — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Houlton's own centroid, and it is not what its county reads: St. Croix County is mostly Western Corn Belt Plains. The wider page above you is answering a different question about different ground.
What Grows in Houlton
Every plant below cleared Houlton's own zone 5a and its 192-day season. Each card opens that plant's Wisconsin profile. How we score.
Is it too late to plant in Houlton?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 25 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What's on the federal record near Houlton
Closest first, within ~10 miles of Houlton. Listing isn't leaking, and distance isn't exposure.
- B AND S RECYCLINGBrownfields · 1900 ft
- VALLEY TOWING & AUTO BODYBrownfields · 2100 ft
- B & J CO INCUnderground Storage Tanks · 0.6 mi
- SC-30/20W/27-0538Nitrate · 0.6 mi
- TUMA EXCUnderground Storage Tanks · 0.8 mi
- SALEHI ALIBrownfields · 1.0 mi
- MOTORSPORT AUTOMOTIVE LTDBrownfields · 1.0 mi
- QUALITY AUTO BODY & BOATBrownfields · 1.0 mi
- Stillwater Yacht ClubUnderground Storage Tanks · 1.0 mi
- MNDOT STILLWATER LIFT BRIDGEBrownfields · 1.0 mi
- CUB FOODS CORPORATE OFFICESBrownfields · 1.0 mi
- 030N20W28ADC 01 Maple IslndNitrate · 1.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Houlton'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 Houlton.
Sources Checked
within ~10 miles of Houlton
Severity Distribution
within ~10 miles of Houlton
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Houlton, Nitrate runs higher than the national average — 306 sites within ~10 miles of Houlton. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around 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 Houlton
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 Houlton average
Your land is one point inside Houlton
Everything above resolves to Houlton as a whole — one PHZM band and one 28°F frost record, read across 936 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 Houlton Average
Houlton Average
- ●USDA Zones 5a, averaged across Houlton
- ●One soil character for all of Houlton
- ●Frost dates read at Houlton's scale: Apr 16 to Oct 25
YOUR Parcel
- ✓Your exact zone, not Houlton's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Houlton
Pull a site-specific report for your exact address in Houlton, Wisconsin — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Houlton averages can't show:
We read public map data around Houlton — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Houlton average
How we know this about Houlton
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 Houlton’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 Houlton
When does frost risk typically end in Houlton?
The last hard freeze (28°F) in Houlton typically lands around Apr 16, 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 7.
When is the first frost in Houlton?
The first hard freeze (28°F) in Houlton typically arrives around Oct 25, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 11, so the watching starts about Sep 25 — about 192 days after the spring freeze cleared.
How long is the growing season in Houlton?
Measured between 28°F hard freezes, Houlton sees about 192 frost-free days — roughly Apr 16 through Oct 25, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 7 to Oct 11, about 157 days.
Is the soil safe to grow vegetables in Houlton?
The federal record around Houlton runs heavier than most — 1,060 documented sites, mostly Brownfields entries (463), the nearest Brownfields record about 0.4 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do I protect my plants from frost in Houlton?
From about Sep 25 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 25 (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 25. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Houlton's scale — its 5a band and its 192-day season. Your yard writes its own version of Houlton'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 Houlton’s own scale
6 of the readings below were taken at Houlton's own scale — its own ~192-day season between 28°F freezes, the 936 acres it covers and 1,060 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Houlton's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Houlton's own 28°F hard-freeze dates, about Apr 16 and Oct 25 and the ~192-day span between themNOAA 1991–2020 Climate Normals
- 1,060 documented contamination sites on the federal record near Houlton, the closest Brownfields record about 0.4 miles out from the town centreFederal environmental registers
- Houlton's boundary and the 936 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~192-day seasonGrowable Ground crop-matching engine
- Houlton sits in the North Central Hardwood Forests — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Houlton's 936 acres read through its county's SSURGO summaryfrom St. Croix County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom St. Croix 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 St. Croix County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Houlton's 936 acreswhy one lot differs from the next →
- Which side of Houlton you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 936 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.4 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 Houlton-wide figureread your own land →
More in Wisconsin
Wider growing context
What grows across WisconsinHoulton sits outside our named growing regions, so Wisconsin as a whole is its closest context here.
Nearby growing guides