Delhi, Iowa, sits in USDA hardiness zone 5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Crops well matched to these conditions include cabbage, cranberry, lavender, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Delhi, 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 Delhi 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 Delhi — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Delhi — the short answer
Delhi, Iowa: USDA zone 5a, about 175 days between hard freezes, across 607 acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 20
- 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
- ~175
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 607 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 Delhi's average, not your lot's — a low corner or a tree line moves it. Against Delhi's 175-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Delhi
Each reading below is measured for Delhi itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredDelhi runs about 175 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
MeasuredDelhi 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 Delhi is in
Delhi sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Delhi's own centroid rather than borrowed from Delaware County.
What Grows in Delhi
Every plant below cleared Delhi's own zone 5a and its 175-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Delhi?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 23; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 20 (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. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
What's on the federal record near Delhi
Closest first, within ~10 miles of Delhi. Listing isn't leaking, and distance isn't exposure.
- 088N04W17CANitrate · 1000 ft
- KWIK STOPUnderground Storage Tanks · 1800 ft
- REUFER INSULATIONUnderground Storage Tanks · 1800 ft
- HARBACHS GARAGEUnderground Storage Tanks · 1900 ft
- 088N04W17DDB 10437 1958Delhi 1Nitrate · 2000 ft
- HARTWICK LAKE MARINA INCUnderground Storage Tanks · 2500 ft
- MAQUOKETA VALLEY COMM SCHOOL DISTUnderground Storage Tanks · 0.5 mi
- PALADIN ATTACHMENTSBrownfields · 0.6 mi
- PALADIN ATTACHMENTSToxics Release Inventory · 0.6 mi
- OCONNELL GRAIN EXPRESSUnderground Storage Tanks · 0.7 mi
- 088N05W24DC 43645 1996Nitrate · 2.7 mi
- GARYS LIQUOR & WINE LTDUnderground Storage Tanks · 2.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Delhi'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 Delhi.
Total Sites
156
within ~10 miles of Delhi
Risk Level
Moderate
Highest-severity
14 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Delhi
Severity Distribution
within ~10 miles of Delhi
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Delhi, Toxics Release Inventory runs higher than the national average — 14 sites within ~10 miles of Delhi. That's not a problem with your land — it's information about it.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Delhi
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 Delhi average
Your land is one point inside Delhi
Everything above resolves to Delhi as a whole — one PHZM band and one 28°F frost record, read across 607 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 Delhi Average
Delhi Average
- ●USDA Zones 5a, averaged across Delhi
- ●One soil character for all of Delhi
- ●Frost dates read at Delhi's scale: Apr 20 to Oct 12
YOUR Parcel
- ✓Your exact zone, not Delhi's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Delhi
Pull a site-specific report for your exact address in Delhi, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Delhi averages can't show:
We read public map data around Delhi — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Delhi average
How we know this about Delhi
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 Delhi’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 Delhi
When does frost risk typically end in Delhi?
The last hard freeze (28°F) in Delhi typically lands around Apr 20, 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 11.
When is the first frost in Delhi?
The first hard freeze (28°F) in Delhi 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 175 days after the spring freeze cleared.
How long is the growing season in Delhi?
Measured between 28°F hard freezes, Delhi sees about 175 frost-free days — roughly Apr 20 through Oct 12, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 11 to Sep 28, about 140 days.
Is the soil safe to grow vegetables in Delhi?
The federal record around Delhi shows 156 documented sites, mostly Underground Storage Tanks entries (84), the nearest Nitrate record about 0.2 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 Delhi?
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 Delhi's scale — its 5a band and its 175-day season. Your yard writes its own version of Delhi'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 Delhi’s own scale
6 of the readings below were taken at Delhi's own scale — its own ~175-day season between 28°F freezes, the 607 acres it covers and 156 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Delhi's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Delhi's own 28°F hard-freeze dates, about Apr 20 and Oct 12 and the ~175-day span between themNOAA 1991–2020 Climate Normals
- 156 documented contamination sites on the federal record near Delhi, the closest Nitrate record about 0.2 miles out from the town centreFederal environmental registers
- Delhi's boundary and the 607 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~175-day seasonGrowable Ground crop-matching engine
- The ecoregion at Delhi'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 Delhi's 607 acres read through its county's SSURGO summaryfrom Delaware County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Delaware 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 Delaware County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Delhi's 607 acreswhy one lot differs from the next →
- Which side of Delhi you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 607 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 0.2 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 Delhi-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaDelhi sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides