The Southern Maryland spans USDA hardiness zones 7b-8a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Southern Maryland is the Western Shore's warm corner — the tri-county Potomac–Chesapeake peninsula (Calvert, Charles, St. Mary's) that the Eastern Shore's Delmarva and Tidewater pages never reach. Tempered on three sides by tidal water on light coastal-plain soils, it runs a zone warmer and roughly a month longer than the Piedmont just to the north: zone 8a with 264 frost-free days in Calvert and 263 in St. Mary's, easing to 7b and 238 days inland in Charles. First frost holds off until early December on the shore (Dec 3 in Calvert, Dec 2 in St. Mary's) with milder winters than Baltimore or Frederick — historic tobacco country that now favors figs, long-season tomatoes, and a real fall greens window. These conditions suit tomato, sweet corn, peach, and crab apple — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
The Southern Maryland spans Maryland.
Your yard isn't all of the Southern Maryland.
The Southern Maryland spans USDA zones 7b-8a, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Southern Maryland — soil, climate, flood, and parcel records. How we handle your address.
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The Southern Maryland — the short answer
The Southern Maryland: USDA zones 7b-8a, 238–264 frost-free days, in Maryland.
- USDA zones
- 7b-8a
- USDA PHZM 2023, aggregated over the footprint
- Frost-free season
- 238–264 days
- NOAA Regional Climate Centers ACIS, 1991-2020
- Counties
- 3
- US Census TIGER/Line 2025
- Region type
- County cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. Where a region publishes no measured season, no season figure is shown.
Hardiness Zone Range
What Grows in the Southern Maryland
Plants matched to the Southern Maryland's USDA zones 7b-8a, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the Southern Maryland
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the Southern Maryland’s USDA zones 7b-8a — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across the Southern Maryland
The USDA soil survey maps this ground county by county. These are those records weighted by land area across three member counties — this region’s own profile, not a state figure.
The ground is predominantly Ultisols, at 79% of mapped acres, followed by Entisols (11%), Inceptisols (6%) and Alfisols (2%). Five soil orders appear somewhere inside the footprint, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Beltsville, Marr, and Grosstown.
36% of those acres are well drained, and another 34% moderately well drained, 13% poorly drained. Topsoil pH runs 4.2–6.2 between the lowest and the highest county on record. 22% of the footprint is classed prime farmland.
Soil order
Ultisols
Drainage
Well drained
Topsoil pH
4.2–6.2
Hydric soils
16%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. St. Mary's County holds the most wetland ground here, at 22% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Southern Maryland
The soil survey reads this ground county by county, and the readings above are those records summed across the Southern Maryland. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records36% of the mapped acres across the Southern Maryland are well drained — ground that drains quickly. That is area-weighted across all three of its mapped counties.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
From county recordsTopsoil across the Southern Maryland runs pH 4.2–6.2 — acidic in all three of them.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Wet ground
From county recordsAbout 16% of the ground across the Southern Maryland is mapped as hydric — wetland — soil. St. Mary's County carries the most, at 22%.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Safe to Grow Here?
What the federal record shows across the Southern Maryland — and how to grow with it.
Across the Southern Maryland's 3 counties the federal record holds 1,771 documented sites, mostly Underground Storage Tanks (831), Nitrate (570) and Brownfields (326). The heaviest single county is Charles County, with 713.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to the Southern Maryland to see which records sit where you actually grow.
Sources Checked
Summed across the 3 counties in the Southern Maryland
A note from Gnorman
What an experienced grower watches for around here
In and around the Southern Maryland, two things run higher than the national average across the 3 counties in the Southern Maryland — Nitrate (570 sites) and PFAS (15 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.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Southern Maryland
Everything above resolves to the Southern Maryland as a whole — a footprint spanning USDA zones 7b-8a. Your parcel sits in exactly one of them. 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 region 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 regional average.
Your Lot vs the Southern Maryland Average
Southern Maryland Average
- ●USDA Zones 7b-8a, averaged across Southern Maryland
- ●One soil character for all of Southern Maryland
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Southern Maryland's 7b-8a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Southern Maryland
Pull a site-specific report for your exact address in the Southern Maryland — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Southern Maryland averages can't show:
We read public map data around The Southern Maryland — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Southern Maryland average
How we know this about the Southern Maryland
The boundary: a cluster of neighboring counties. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the Southern Maryland
What hardiness zone is the Southern Maryland?
The Southern Maryland spans USDA hardiness zones 7b-8a, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the Southern Maryland?
Measured between 28°F hard freezes, the Southern Maryland's counties mostly run 251 to 264 frost-free days, median 263 (NOAA Regional Climate Centers ACIS, 1991–2020, over 3 member counties). That 13-day spread is the honest read — no single season describes 3 counties, and each county guide below carries its own.
When does frost risk end in the Southern Maryland?
Across the Southern Maryland, the middle half of member counties see their last 28°F hard freeze between Mar 14 and Mar 19 (median Mar 14), and their first fall freeze between Nov 24 and Dec 3. Those are hard freezes, not the last light frost: tender transplants wait for about Apr 4, and elevation decides which end of a 5-day spread you garden in.
What grows well in the Southern Maryland?
The Southern Maryland's conditions suit plants such as Tomato, Sweet Corn, Peach, Crab Apple, Black-eyed Susan. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the Southern Maryland defined?
The Southern Maryland is defined here as a curated cluster of 3 neighboring counties that share a growing character. Growing regions have no official boundary, so this footprint is our published one — every county in it is named on this page.
Which states does the Southern Maryland cover?
The Southern Maryland spans Maryland. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Appalachia, Tidewater & Chesapeake, Delmarva Peninsula, Maryland Piedmont, and Cumberland Valley share at least one state with the Southern Maryland. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the Southern Maryland’s own scale
6 of the readings below were taken at the Southern Maryland's own scale — the zone 7b-8a band across its footprint, a median 263-day season across its 3 counties and 1,771 documented federal contamination records across its 3 counties, 713 of them in Charles County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 7b-8a aggregated across all 3 counties in the footprintUSDA PHZM 2023
- The boundary itself — the 3 counties this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 3 counties run 251 to 264 frost-free days, median 263NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 1,771 documented federal contamination records across its 3 counties, 713 of them in Charles County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 79% Ultisols, topsoil pH 4.2–6.2, area-weighted across its 3 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 7b-8afrom Maryland
What this page can’t tell you
- Which end of the 13-day range your ground sits at — 251 days at one extreme, 264 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the Southern Maryland
State growing guides
Counties in this region
Other growing regions across Maryland
The vast eastern mountain region of steep hollows, thin acidic soils, and short upland seasons — apples, brambles, ramps, and forest crops on hard-won ground. (Union of the core Appalachian ecoregions.)
The low, flat, tidal coastal plain around Chesapeake Bay — sandy soils, mild maritime winters, and a long season for vegetables and Southern staples.
A flat coastal-plain peninsula of sandy, well-drained soils between the Chesapeake and the Atlantic — a major sweet-corn, soybean, and produce region.
Maryland's crystalline-rock foothill belt between the fall line and the Blue Ridge — heavy clay and silt loams over ancient bedrock, later spring frosts, and a roughly 217–234-day inland season that sets it apart from the sandy Delmarva coast and the cold western mountains. (EPA Northern Piedmont, ecoregion 64 — a separate region from the southern Piedmont; Baltimore City runs a zone warmer as an urban heat island.)
The Cumberland Valley is the Great Valley's northern anchor — the same limestone floor that runs south into the Shenandoah, but colder-wintered and shorter-seasoned, and split by the Mason-Dixon line across Cumberland and Franklin counties in Pennsylvania and Washington County in Maryland. Scoped to just those three, the picture tightens to a uniform USDA zone 7a and a 215-to-219-day frost-free season — last frost in early April, first in early November — steadier than the wide 5b-8b range the broader Appalachian page has to average across. The valley reads in two halves: a flat limestone floor where cold air pools on clear spring nights, long given over to dairy pasture, hay, and grain, and the elevated Blue Ridge benches of South Mountain along the eastern edge, where good cold-air drainage has kept apple and peach orchards in business for generations. Those same well-drained slopes carry the federally recognized Cumberland Valley AVA's wine grapes.