Carroll County, in Maryland, sits in USDA hardiness zone 7a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
On paper, tomato, black-eyed susan, peach, and sweet corn all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Carroll County holds more than one microclimate.
Soils and elevations shift across Carroll 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
7a
Last Hard Freeze (28°F)
Mar 21
County normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Nov 25
County normal — light frosts arrive a few weeks earlier
County Area
286K acres
Hardiness Zone Range
Zone maps are averages across Carroll County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Carroll County
Across Carroll County, the ground is predominantly Ultisols, where Brinklow, Glenelg, and Penn are the most extensive named soil series. The soil is generally well drained with a channery loam surface. Topsoil pH runs about 5.2–6.0, moderately acidic. Rainfall drains through hydrologic group B soils.
Soil order
Ultisols
Drainage
Well drained
Prime farmland
39%
Hydric soils
6%
Soil still varies lot by lot — soil types explained.
What Grows in Carroll County
Plants matched to Carroll County's USDA zones 7a — each links to its full growing profile.
Is it too late to plant in Carroll County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Feb 21; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 21 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 25 — long-season crops need about 90 days of runway, quick greens only 30. A long window like this one runs successions deep into fall — and even its last weeks take quick greens and garlic.
Growing Challenges in Maryland
What an experienced grower plans around here — each one has a move.
Heavy Piedmont clay drains poorly
A raised bed today, compost every fall — Piedmont clay becomes an asset once the drainage is yours.
Humidity and heat in summer promote disease
Morning watering at the base, room to breathe between plants, resistant varieties — the humid-summer basics, per your extension.
Deer pressure in suburban areas is extreme
A tall fence is the answer that holds; for everything outside it, lean toward the plants deer reliably skip.
For cultivar selection, pest pressure, and planting-time guidance specific to Maryland, the University of Maryland Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Carroll County — and how to grow with it.
We checked the federal record across Carroll County — 862 documented sites across 8 of the 9 source types we track.
The most significant on record: 3 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Carroll 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.
Severity Distribution
across Carroll County
Highest-Severity Sites
Know Before You Grow
- •Underground tanks can leak petroleum products. Soil testing near former gas stations is recommended.
- •Raised beds with imported soil can reduce exposure risk near brownfield sites.
- •Test well water for nitrates if you rely on a private well. Levels above 10 mg/L require treatment.
Check your specific parcel in Carroll 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
Carroll County Average
- ●USDA Zones 7a
- ●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 Carroll County
Pull a site-specific report for your exact address in Carroll County, Maryland — 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 Carroll County, Maryland
- USDA Hardiness Zones: 7a (USDA PHZM 2023)
- Last Hard Freeze (28°F): Mar 21 (county normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Nov 25 (county normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~249 (county normal, NOAA 1991–2020 Climate Normals)
- County Land Area: 286K 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 Carroll 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 Carroll County, Maryland?
Carroll County sits in USDA hardiness zone 7a, 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 Carroll County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Feb 21; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 21 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 25 — long-season crops need about 90 days of runway, quick greens only 30. A long window like this one runs successions deep into fall — and even its last weeks take quick greens and garlic.
When does frost risk typically end in Carroll County?
The last hard freeze (28°F) in Carroll County typically lands around Mar 21, 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 Carroll County?
Measured between 28°F hard freezes, Carroll County sees about 249 frost-free days — roughly Mar 21 through Nov 25, 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 Carroll County?
Carroll County's zone 7a supports a wide range — strong performers include Tomato, Black-eyed Susan, Peach, Sweet Corn, and Crab 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 Carroll County, really?
Officially, Carroll County sits in USDA zone 7a (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 Carroll County?
The federal record around Carroll County runs heavier than most — 862 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 Carroll County — what should I know before planting?
Start with three facts. Carroll County sits in USDA zone 7a, which sets what survives winter; the last 28°F hard freeze typically clears around Mar 21, with about 249 frost-free days to work with (NOAA 1991–2020 climate normals); and 862 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 Carroll 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 Maryland's frost window, season length, and soil profile against the plant's real requirements.