Allen County, in Indiana, sits in USDA hardiness zone 6a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Crops well matched to these conditions include tomato, sweet corn, pawpaw, and peony — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Allen County holds more than one microclimate.
Soils and elevations shift across Allen County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Quick Facts
USDA Zones
6a
Last Hard Freeze (28°F)
Mar 27
County normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Nov 18
County normal — light frosts arrive a few weeks earlier
County Area
421K acres
Hardiness Zone Range
Zone maps are averages across Allen County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Allen County
Across Allen County, the ground is predominantly Alfisols, where Blount, Pewamo, and Glynwood are the most extensive named soil series. The soil is generally very poorly drained with a silt loam surface. Topsoil pH runs about 6.4–6.5, slightly acidic. Rainfall drains through hydrologic group C/D soils.
Soil order
Alfisols
Drainage
Very poorly drained
Prime farmland
13%
Hydric soils
43%
Soil still varies lot by lot — soil types explained.
What Grows in Allen County
Plants matched to Allen County's USDA zones 6a — each links to its full growing profile.
Is it too late to plant in Allen County?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Feb 27; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 18 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
Growing Challenges in Indiana
What an experienced grower plans around here — each one has a move.
Heavy clay soils limit drainage in many areas
Mounded rows and compost open clay up — and where water still stands, a raised bed ends the argument.
Late spring frosts through early May
Hold tender transplants until your local last-frost normal clears — hardy greens will happily take the early slot.
Hot humid summers promote blight and mildew
Mulch to stop soil splash, water at the base, and rotate crop families — the blight playbook your extension teaches.
For cultivar selection, pest pressure, and planting-time guidance specific to Indiana, the Purdue Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Allen County — and how to grow with it.
We checked the federal record across Allen County — 1,700 documented sites across 7 of the 9 source types we track.
The most significant on record: 10 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Allen County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Sources Checked
across Allen County
Severity Distribution
across Allen County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Allen County, Toxic Release Inventory runs higher than the national average — 165 sites nearby. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Toxic 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 Allen County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Allen County Average
- ●USDA Zones 6a
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Allen County
Pull a site-specific report for your exact address in Allen County, Indiana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Allen County, Indiana
- USDA Hardiness Zones: 6a (USDA PHZM 2023)
- Last Hard Freeze (28°F): Mar 27 (county normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Nov 18 (county normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~236 (county normal, NOAA 1991–2020 Climate Normals)
- County Land Area: 421K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Allen County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Allen County, Indiana?
Allen County sits in USDA hardiness zone 6a, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
Is it too late to plant in Allen County?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Feb 27; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 18 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
When does frost risk typically end in Allen County?
The last hard freeze (28°F) in Allen County typically lands around Mar 27, per NOAA 1991–2020 climate normals — an earlier marker than the light-frost dates many planting charts quote. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
How long is the growing season in Allen County?
Measured between 28°F hard freezes, Allen County sees about 236 frost-free days — roughly Mar 27 through Nov 18, per NOAA 1991–2020 climate normals. Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
What vegetables grow in Allen County?
Allen County's zone 6a supports a wide range — strong performers include Tomato, Sweet Corn, Pawpaw, Peony, and Apple. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Allen County, really?
Officially, Allen County sits in USDA zone 6a (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Allen County?
The federal record around Allen County runs heavier than most — 1,700 documented sites — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
Just moved to Allen County — what should I know before planting?
Start with three facts. Allen County sits in USDA zone 6a, which sets what survives winter; the last 28°F hard freeze typically clears around Mar 27, with about 236 frost-free days to work with (NOAA 1991–2020 climate normals); and 1,700 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Allen County average. Your yard writes its own version — we read soil, sun, drainage, and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Indiana's frost window, season length, and soil profile against the plant's real requirements.