Cobb Island, Maryland, sits in USDA hardiness zone 8a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Growers here do well with cabbage, fig, california poppy, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Cobb Island, 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 Cobb Island 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 Cobb Island — soil, climate, flood, and parcel records. How we handle your address.
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Cobb Island — the short answer
Cobb Island, Maryland: USDA zone 8a, about 267 days between hard freezes, across 401 acres of town.
- USDA zone
- 8a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 12
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Dec 4
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~267
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 401 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 8a is Cobb Island's average, not your lot's — a low corner or a tree line moves it. Against Cobb Island's 267-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Cobb Island
Each reading below is measured for Cobb Island itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredCobb Island runs about 267 days between hard freezes — close to year-round growing.
Frost is rarely the limit here; winter plantings are as real as summer ones, and the harder question is which crops shrug off the summer heat.
Grow cool-season crops through the mild winter, and choose heat-tolerant varieties for the summer beds.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredCobb Island sits in USDA hardiness zone 8a.
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 Cobb Island is in
Cobb Island sits in the Middle Atlantic Coastal Plain — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Cobb Island's own centroid, and it is not what its county reads: Charles County is mostly Southeastern Plains. The wider page above you is answering a different question about different ground.
What Grows in Cobb Island
Every plant below cleared Cobb Island's own zone 8a and its 267-day season. Each card opens that plant's Maryland profile. How we score.
Is it too late to plant in Cobb Island?
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 12; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 12 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 4 — long-season crops need about 90 days of runway, quick greens only 30. And with a calendar this mild, the honest answer is that planting barely stops — winter opens seasons colder regions never see.
Documented around Cobb Island
Spotted lanternfly documented 14 miles from Cobb Island, first recorded 2023. What to watch for.
What's on the federal record near Cobb Island
Closest first, within ~10 miles of Cobb Island. Listing isn't leaking, and distance isn't exposure.
- Florence M. SaundersUnderground Storage Tanks · 250 ft
- 01- 9999999 (S. Norris Tackle)Underground Storage Tanks · 250 ft
- Cobb Island MarketUnderground Storage Tanks · 250 ft
- MD SHA BRIDGE 0803800Brownfields · 250 ft
- Shymansky's Marina & RestaurantUnderground Storage Tanks · 500 ft
- Pirates Den MarinaUnderground Storage Tanks · 500 ft
- Cobb Island VFDUnderground Storage Tanks · 650 ft
- Capt. John's CrabhouseUnderground Storage Tanks · 1700 ft
- CH Ff 13Nitrate · 2300 ft
- CH Ff 18Nitrate · 0.6 mi
- J. Earl Hill StoreUnderground Storage Tanks · 0.9 mi
- DOLLAR GENERAL STORE #22703Brownfields · 1.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Cobb Island'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 Cobb Island.
Total Sites
206
within ~10 miles of Cobb Island
Risk Level
Elevated
Highest-severity
2 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Cobb Island
Severity Distribution
within ~10 miles of Cobb Island
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Cobb Island, two things run higher than the national average within ~10 miles of Cobb Island — Nitrate (61 sites) and Underground Storage Tanks (128 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.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Cobb Island
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 Cobb Island average
Your land is one point inside Cobb Island
Everything above resolves to Cobb Island as a whole — one PHZM band and one 28°F frost record, read across 401 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 Cobb Island Average
Cobb Island Average
- ●USDA Zones 8a, averaged across Cobb Island
- ●One soil character for all of Cobb Island
- ●Frost dates read at Cobb Island's scale: Mar 12 to Dec 4
YOUR Parcel
- ✓Your exact zone, not Cobb Island's 8a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Cobb Island
Pull a site-specific report for your exact address in Cobb Island, Maryland — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Cobb Island averages can't show:
We read public map data around Cobb Island — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Cobb Island average
How we know this about Cobb Island
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 Cobb Island’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 Cobb Island
When does frost risk typically end in Cobb Island?
The last hard freeze (28°F) in Cobb Island typically lands around Mar 12, 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 Apr 2.
When is the first frost in Cobb Island?
The first hard freeze (28°F) in Cobb Island typically arrives around Dec 4, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 20, so the watching starts about Nov 4 — about 267 days after the spring freeze cleared.
How long is the growing season in Cobb Island?
Measured between 28°F hard freezes, Cobb Island sees about 267 frost-free days — roughly Mar 12 through Dec 4, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 2 to Nov 20, about 232 days.
Is the soil safe to grow vegetables in Cobb Island?
The federal record around Cobb Island is a meaningful one — 206 documented sites, mostly Underground Storage Tanks entries (128), the nearest Underground Storage Tanks record under a tenth of a mile out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in Cobb Island?
From about Nov 4 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 Dec 4 (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 Dec 4. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Cobb Island's scale — its 8a band and its 267-day season. Your yard writes its own version of Cobb Island'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 Cobb Island’s own scale
7 of the readings below were taken at Cobb Island's own scale — its own ~267-day season between 28°F freezes, the 401 acres it covers and 206 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Cobb Island's own USDA hardiness band, zones 8aUSDA PHZM 2023
- Cobb Island's own 28°F hard-freeze dates, about Mar 12 and Dec 4 and the ~267-day span between themNOAA 1991–2020 Climate Normals
- 206 documented contamination sites on the federal record near Cobb Island, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Cobb Island's boundary and the 401 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8a and a ~267-day seasonGrowable Ground crop-matching engine
- Cobb Island sits in the Middle Atlantic Coastal Plain — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Cobb Islandlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Cobb Island's 401 acres read through its county's SSURGO summaryfrom Charles County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Charles County
- The growing challenges every Maryland grower plans around — written at state scale, so they stay on the state guidefrom Maryland
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Charles County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Cobb Island's 401 acreswhy one lot differs from the next →
- Which side of Cobb Island you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 401 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 Cobb Island-wide figureread your own land →
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