Twin Lakes, Iowa, sits in USDA hardiness zone 5a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Expect cabbage, cranberry, lavender, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Twin Lakes, 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 Twin Lakes 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 Twin Lakes — soil, climate, flood, and parcel records. How we handle your address.
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Twin Lakes — the short answer
Twin Lakes, Iowa: USDA zone 5a, about 190 days between hard freezes, across 846 acres of town.
- 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
- Town area
- 846 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 Twin Lakes's average, not your lot's — a low corner or a tree line moves it. Against Twin Lakes's 190-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Twin Lakes
Each reading below is measured for Twin Lakes itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredTwin Lakes 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
MeasuredTwin Lakes 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 Twin Lakes is in
Twin Lakes sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Twin Lakes's own centroid rather than borrowed from Calhoun County.
What Grows in Twin Lakes
Every plant below cleared Twin Lakes'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 Twin Lakes?
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 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. 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 Twin Lakes
Closest first, within ~10 miles of Twin Lakes. Listing isn't leaking, and distance isn't exposure.
- TWIN LAKES GROCERYUnderground Storage Tanks · 300 ft
- 088N33W12BACNitrate · 1.9 mi
- FORMER CAL CAR SERVICEUnderground Storage Tanks · 2.8 mi
- IDOT SHOPUnderground Storage Tanks · 2.8 mi
- NORTHERN NATURAL GAS - MANSON TBSBrownfields · 4.1 mi
- CAL CAR SERVICE COUnderground Storage Tanks · 4.4 mi
- AT&T COMMUNICATIONSUnderground Storage Tanks · 4.4 mi
- Not KnownUnderground Storage Tanks · 4.6 mi
- SPIESS DX-KnokeUnderground Storage Tanks · 4.6 mi
- JOHNSON OIL COMPANYUnderground Storage Tanks · 5.0 mi
- POMEROY-PALMER HIGH SCHOOLBrownfields · 5.2 mi
- POMEROY COMM SCHOOLUnderground Storage Tanks · 5.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Twin Lakes'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 Twin Lakes.
Total Sites
106
within ~10 miles of Twin Lakes
Risk Level
Moderate
Highest-severity
3 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Twin Lakes
Severity Distribution
within ~10 miles of Twin Lakes
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Twin Lakes, Nitrate runs higher than the national average — 32 sites within ~10 miles of Twin Lakes. That's not a problem with your land — it's information about 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 Twin Lakes
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 Twin Lakes average
Your land is one point inside Twin Lakes
Everything above resolves to Twin Lakes as a whole — one PHZM band and one 28°F frost record, read across 846 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 Twin Lakes Average
Twin Lakes Average
- ●USDA Zones 5a, averaged across Twin Lakes
- ●One soil character for all of Twin Lakes
- ●Frost dates read at Twin Lakes's scale: Apr 15 to Oct 22
YOUR Parcel
- ✓Your exact zone, not Twin Lakes's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Twin Lakes
Pull a site-specific report for your exact address in Twin Lakes, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Twin Lakes averages can't show:
We read public map data around Twin Lakes — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Twin Lakes average
How we know this about Twin Lakes
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 Twin Lakes’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 Twin Lakes
When does frost risk typically end in Twin Lakes?
The last hard freeze (28°F) in Twin Lakes 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 Twin Lakes?
The first hard freeze (28°F) in Twin Lakes 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 Twin Lakes?
Measured between 28°F hard freezes, Twin Lakes 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 Twin Lakes?
The federal record around Twin Lakes shows 106 documented sites, mostly Underground Storage Tanks entries (54), 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 Twin Lakes?
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 Twin Lakes's scale — its 5a band and its 190-day season. Your yard writes its own version of Twin Lakes'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 Twin Lakes’s own scale
6 of the readings below were taken at Twin Lakes's own scale — its own ~190-day season between 28°F freezes, the 846 acres it covers and 106 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Twin Lakes's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Twin Lakes's own 28°F hard-freeze dates, about Apr 15 and Oct 22 and the ~190-day span between themNOAA 1991–2020 Climate Normals
- 106 documented contamination sites on the federal record near Twin Lakes, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Twin Lakes's boundary and the 846 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 Twin Lakes'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 Twin Lakes's 846 acres read through its county's SSURGO summaryfrom Calhoun County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Calhoun 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 Calhoun County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Twin Lakes's 846 acreswhy one lot differs from the next →
- Which side of Twin Lakes you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 846 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 Twin Lakes-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaTwin Lakes sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides