Callender, Iowa, sits in USDA hardiness zone 5a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
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 Callender, 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 Callender 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 Callender — soil, climate, flood, and parcel records. How we handle your address.
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Callender — the short answer
Callender, Iowa: USDA zone 5a, about 190 days between hard freezes, across 337 acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 15
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 22
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~190
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 337 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 Callender's average, not your lot's — a low corner or a tree line moves it. Against Callender's 190-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Callender
Each reading below is measured for Callender itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredCallender runs about 190 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
MeasuredCallender 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 Callender is in
Callender sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Callender's own centroid rather than borrowed from Webster County.
What Grows in Callender
Every plant below cleared Callender's own zone 5a and its 190-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Callender?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 18; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 15 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 22 — 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 Callender
Closest first, within ~10 miles of Callender. Listing isn't leaking, and distance isn't exposure.
- MARVIN''S STANDARDUnderground Storage Tanks · 50 ft
- PRAIRIE COMM SCHOOLUnderground Storage Tanks · 300 ft
- 087N30W12BCD 00918 1938Callender 1Nitrate · 750 ft
- 087N30W12CABD 25484 1979Callender 2Nitrate · 900 ft
- STAR ENERGYUnderground Storage Tanks · 1100 ft
- WEBSTER CO MAINT BLDGUnderground Storage Tanks · 1900 ft
- 087N30W12CAC 02391 1946Callender TowerNitrate · 2100 ft
- 087N30W12DBC 04543 1949Callender 3Nitrate · 0.6 mi
- 087N30W03BAB 03426 1948Nitrate · 2.2 mi
- POET BIOREFINING - GOWRIE LLCBrownfields · 2.9 mi
- 087N29W09BBNitrate · 2.9 mi
- POET BIOREFINING - GOWRIE, LLCToxics Release Inventory · 2.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Callender'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 Callender.
Total Sites
134
within ~10 miles of Callender
Risk Level
Moderate
Highest-severity
10 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Callender
Severity Distribution
within ~10 miles of Callender
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Callender, two things run higher than the national average within ~10 miles of Callender — Nitrate (62 sites) and Toxics Release Inventory (10 sites). 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.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Callender
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 Callender average
Your land is one point inside Callender
Everything above resolves to Callender as a whole — one PHZM band and one 28°F frost record, read across 337 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 Callender Average
Callender Average
- ●USDA Zones 5a, averaged across Callender
- ●One soil character for all of Callender
- ●Frost dates read at Callender's scale: Apr 15 to Oct 22
YOUR Parcel
- ✓Your exact zone, not Callender's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Callender
Pull a site-specific report for your exact address in Callender, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Callender averages can't show:
We read public map data around Callender — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Callender average
How we know this about Callender
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 Callender’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 Callender
When does frost risk typically end in Callender?
The last hard freeze (28°F) in Callender typically lands around Apr 15, 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 6.
When is the first frost in Callender?
The first hard freeze (28°F) in Callender typically arrives around Oct 22, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 8, so the watching starts about Sep 22 — about 190 days after the spring freeze cleared.
How long is the growing season in Callender?
Measured between 28°F hard freezes, Callender sees about 190 frost-free days — roughly Apr 15 through Oct 22, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 6 to Oct 8, about 155 days.
Is the soil safe to grow vegetables in Callender?
The federal record around Callender shows 134 documented sites, mostly Nitrate entries (62), the nearest Underground Storage Tanks 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 Callender?
From about Sep 22 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 22 (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 22. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Callender's scale — its 5a band and its 190-day season. Your yard writes its own version of Callender'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 Callender’s own scale
6 of the readings below were taken at Callender's own scale — its own ~190-day season between 28°F freezes, the 337 acres it covers and 134 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Callender's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Callender's own 28°F hard-freeze dates, about Apr 15 and Oct 22 and the ~190-day span between themNOAA 1991–2020 Climate Normals
- 134 documented contamination sites on the federal record near Callender, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Callender's boundary and the 337 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~190-day seasonGrowable Ground crop-matching engine
- The ecoregion at Callender'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 Callender's 337 acres read through its county's SSURGO summaryfrom Webster County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Webster 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 Webster County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Callender's 337 acreswhy one lot differs from the next →
- Which side of Callender you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 337 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks 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 Callender-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaCallender sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides