Denham, Minnesota, sits in USDA hardiness zone 4a — a zone band wide enough that plant choice, not possibility, is the interesting question.
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 Denham, 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 Denham 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 Denham — soil, climate, flood, and parcel records. How we handle your address.
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Denham — the short answer
Denham, Minnesota: USDA zone 4a, about 156 days between hard freezes, across 849 acres of city.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 3
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~156
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 849 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 4a is Denham's average, not your lot's — a low corner or a tree line moves it. Against Denham's 156-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Denham
Each reading below is measured for Denham itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredDenham runs about 156 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
MeasuredDenham sits in USDA hardiness zone 4a.
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 Denham is in
Denham sits in the Northern Lakes and Forests — EPA Level III, inside the wider Northern Forests. That is read at Denham's own centroid rather than borrowed from Pine County.
What Grows in Denham
Every plant below cleared Denham's own zone 4a and its 156-day season. Each card opens that plant's Minnesota profile. How we score.
Is it too late to plant in Denham?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 5; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 3 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 6 — 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 Denham
Closest first, within ~10 miles of Denham. Listing isn't leaking, and distance isn't exposure.
- 552670Nitrate · 0.7 mi
- 172884Nitrate · 1.1 mi
- 620410Nitrate · 1.1 mi
- 191221Nitrate · 1.8 mi
- 045N21W11DDD 01 G CarlsonNitrate · 2.0 mi
- 555935Nitrate · 3.0 mi
- ALBERG AUTO LLCBrownfields · 3.7 mi
- Windemere Township Town HallUnderground Storage Tanks · 4.0 mi
- Ymca Camp MillerUnderground Storage Tanks · 4.0 mi
- GteUnderground Storage Tanks · 4.0 mi
- 573736Nitrate · 4.8 mi
- 573740Nitrate · 5.0 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Denham'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 Denham.
Sources Checked
within ~10 miles of Denham
Severity Distribution
within ~10 miles of Denham
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Denham, Nitrate runs higher than the national average — 58 sites within ~10 miles of Denham. 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 Denham
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 Denham average
Your land is one point inside Denham
Everything above resolves to Denham as a whole — one PHZM band and one 28°F frost record, read across 849 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 Denham Average
Denham Average
- ●USDA Zones 4a, averaged across Denham
- ●One soil character for all of Denham
- ●Frost dates read at Denham's scale: May 3 to Oct 6
YOUR Parcel
- ✓Your exact zone, not Denham's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Denham
Pull a site-specific report for your exact address in Denham, Minnesota — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Denham averages can't show:
We read public map data around Denham — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Denham average
How we know this about Denham
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 Denham’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 Denham
When does frost risk typically end in Denham?
The last hard freeze (28°F) in Denham typically lands around May 3, 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 24.
When is the first frost in Denham?
The first hard freeze (28°F) in Denham typically arrives around Oct 6, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 22, so the watching starts about Sep 6 — about 156 days after the spring freeze cleared.
How long is the growing season in Denham?
Measured between 28°F hard freezes, Denham sees about 156 frost-free days — roughly May 3 through Oct 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 24 to Sep 22, about 121 days.
Is the soil safe to grow vegetables in Denham?
The federal record around Denham shows 95 documented sites, mostly Nitrate entries (58), the nearest Nitrate record about 0.7 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 Denham?
From about Sep 6 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 6 (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 6. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Denham's scale — its 4a band and its 156-day season. Your yard writes its own version of Denham'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 Denham’s own scale
6 of the readings below were taken at Denham's own scale — its own ~156-day season between 28°F freezes, the 849 acres it covers and 95 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Denham's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Denham's own 28°F hard-freeze dates, about May 3 and Oct 6 and the ~156-day span between themNOAA 1991–2020 Climate Normals
- 95 documented contamination sites on the federal record near Denham, the closest Nitrate record about 0.7 miles out from the town centreFederal environmental registers
- Denham's boundary and the 849 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~156-day seasonGrowable Ground crop-matching engine
- The ecoregion at Denham's own centroid, the Northern Lakes and ForestsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Denham's 849 acres read through its county's SSURGO summaryfrom Pine County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Pine County
- The growing challenges every Minnesota grower plans around — written at state scale, so they stay on the state guidefrom Minnesota
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Pine County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Denham's 849 acreswhy one lot differs from the next →
- Which side of Denham you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 849 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 0.7 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 Denham-wide figureread your own land →
More in Minnesota
Wider growing context
What grows across MinnesotaDenham sits outside our named growing regions, so Minnesota as a whole is its closest context here.
Nearby growing guides