Monticello, Iowa, sits in USDA hardiness zone 5a — a zone band wide enough that plant choice, not possibility, is the interesting question.
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 Monticello, 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 Monticello 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 Monticello — soil, climate, flood, and parcel records. How we handle your address.
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Monticello — the short answer
Monticello, Iowa: USDA zone 5a, about 184 days between hard freezes, across 4K acres of city.
- 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 17
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~184
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 4K 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 Monticello's average, not your lot's — a low corner or a tree line moves it. Against Monticello's 184-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Monticello
Each reading below is measured for Monticello itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredMonticello runs about 184 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
MeasuredMonticello 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 Monticello is in
Monticello sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Monticello's own centroid rather than borrowed from Jones County.
What Grows in Monticello
Every plant below cleared Monticello's own zone 5a and its 184-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Monticello?
For most of the year, no — what changes is which crops still fit the days remaining. 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 17 — 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 Monticello
Closest first, within ~10 miles of Monticello. Listing isn't leaking, and distance isn't exposure.
- SCHERRMANS IMPLEMENTBrownfields · 350 ft
- WEARS INCUnderground Storage Tanks · 450 ft
- CASEY''S GENERAL STORE 1889Underground Storage Tanks · 700 ft
- 086N03W27BCCC 00917 1925Monticello 2Nitrate · 800 ft
- K POWER FUELSUnderground Storage Tanks · 900 ft
- MONTICELLO SENIOR HOMEUnderground Storage Tanks · 1000 ft
- MONTICELLO COMMUNITY SCHOOLSUnderground Storage Tanks · 1000 ft
- CITY OF MONTICELLOUnderground Storage Tanks · 1100 ft
- STAR MANUFACTURINGUnderground Storage Tanks · 1200 ft
- CASEY''S GENERAL STORE #3221Underground Storage Tanks · 1300 ft
- MONTICELLO HIGH SCHOOLBrownfields · 1300 ft
- SMOTHERS EQUIPMENT INCBrownfields · 1400 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Monticello'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 Monticello.
Total Sites
148
within ~10 miles of Monticello
Risk Level
Moderate
Highest-severity
6 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Monticello
Severity Distribution
within ~10 miles of Monticello
Highest-Severity Sites
Know Before You Grow
- •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.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Check your specific parcel in Monticello
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 Monticello average
Your land is one point inside Monticello
Everything above resolves to Monticello as a whole — one PHZM band and one 28°F frost record, read across 4K 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 Monticello Average
Monticello Average
- ●USDA Zones 5a, averaged across Monticello
- ●One soil character for all of Monticello
- ●Frost dates read at Monticello's scale: Apr 16 to Oct 17
YOUR Parcel
- ✓Your exact zone, not Monticello's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Monticello
Pull a site-specific report for your exact address in Monticello, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Monticello averages can't show:
We read public map data around Monticello — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Monticello average
How we know this about Monticello
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 Monticello’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 Monticello
When does frost risk typically end in Monticello?
The last hard freeze (28°F) in Monticello 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 Monticello?
The first hard freeze (28°F) in Monticello typically arrives around Oct 17, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 3, so the watching starts about Sep 17 — about 184 days after the spring freeze cleared.
How long is the growing season in Monticello?
Measured between 28°F hard freezes, Monticello sees about 184 frost-free days — roughly Apr 16 through Oct 17, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 7 to Oct 3, about 149 days.
Is the soil safe to grow vegetables in Monticello?
The federal record around Monticello shows 148 documented sites, mostly Underground Storage Tanks entries (85), the nearest Brownfields record under a tenth of a mile 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 Monticello?
From about Sep 17 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 17 (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 17. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Monticello's scale — its 5a band and its 184-day season. Your yard writes its own version of Monticello'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 Monticello’s own scale
6 of the readings below were taken at Monticello's own scale — its own ~184-day season between 28°F freezes, the 3,601 acres it covers and 148 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Monticello's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Monticello's own 28°F hard-freeze dates, about Apr 16 and Oct 17 and the ~184-day span between themNOAA 1991–2020 Climate Normals
- 148 documented contamination sites on the federal record near Monticello, the closest Brownfields record under a tenth of a mile out from the town centreFederal environmental registers
- Monticello's boundary and the 3,601 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~184-day seasonGrowable Ground crop-matching engine
- The ecoregion at Monticello's own centroid, the Western Corn Belt PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Monticello's 3,601 acres read through its county's SSURGO summaryfrom Jones County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Jones County
- The growing challenges every Iowa grower plans around — written at state scale, so they stay on the state guidefrom Iowa
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Jones County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Monticello's 3,601 acreswhy one lot differs from the next →
- Which side of Monticello you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 3,601 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields 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 Monticello-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaMonticello sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides