South Windham, Connecticut, sits in USDA hardiness zone 6b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Growers here do well with cabbage, hazelnut, lavender, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in South Windham, 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 South Windham 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 South Windham — soil, climate, flood, and parcel records. How we handle your address.
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South Windham — the short answer
South Windham, Connecticut: USDA zone 6b, about 203 days between hard freezes, across 2K acres of town.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 26
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~203
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 2K 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 6b is South Windham's average, not your lot's — a low corner or a tree line moves it. Against South Windham's 203-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in South Windham
Each reading below is measured for South Windham itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSouth Windham runs about 203 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredSouth Windham sits in USDA hardiness zone 6b.
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 South Windham is in
South Windham sits in the Northeastern Coastal Zone — EPA Level III, inside the wider Eastern Temperate Forests. That is read at South Windham's own centroid rather than borrowed from Southeastern Connecticut Planning Region.
What Grows in South Windham
Every plant below cleared South Windham's own zone 6b and its 203-day season. Each card opens that plant's Connecticut profile. How we score.
Is it too late to plant in South Windham?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Mar 9; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 6 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 26 — 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.
Documented around South Windham
Spotted lanternfly documented 11 miles from South Windham, first recorded 2022. What to watch for.
What's on the federal record near South Windham
Closest first, within ~10 miles of South Windham. Listing isn't leaking, and distance isn't exposure.
- ROGERS ELASTOMER COMPONENTS DIVISONToxics Release Inventory · 2300 ft
- CT-WIL 10Nitrate · 0.6 mi
- Landon TireUnderground Storage Tanks · 0.7 mi
- HAIN MATERIALS COMPANYUnderground Storage Tanks · 0.9 mi
- HAIN BROTHERS MATERIALS COMPANYBrownfields · 0.9 mi
- CT-WIL 12Nitrate · 1.1 mi
- H. L. DIEHLSuperfund · 1.2 mi
- WINDHAM MATERIALS LLCUnderground Storage Tanks · 1.3 mi
- CT-WIL 42Nitrate · 1.5 mi
- TENNETT TREE SERVICE, INC.Underground Storage Tanks · 1.8 mi
- L. G. WHEATON INC.Underground Storage Tanks · 1.8 mi
- WILLIMANTIC OFFICEUnderground Storage Tanks · 1.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from South Windham'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 South Windham.
Total Sites
624
within ~10 miles of South Windham
Risk Level
Elevated
Highest-severity
10 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of South Windham
Severity Distribution
within ~10 miles of South Windham
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around South Windham, two things run higher than the national average within ~10 miles of South Windham — Superfund (10 sites) and CAFO (6 sites). That's not a problem with your land — it's information about it.
Superfund: Superfund sites represent the most severe contamination in the federal system.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Check your specific parcel in South Windham
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 South Windham average
Your land is one point inside South Windham
Everything above resolves to South Windham as a whole — one PHZM band and one 28°F frost record, read across 2K 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 South Windham Average
South Windham Average
- ●USDA Zones 6b, averaged across South Windham
- ●One soil character for all of South Windham
- ●Frost dates read at South Windham's scale: Apr 6 to Oct 26
YOUR Parcel
- ✓Your exact zone, not South Windham's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in South Windham
Pull a site-specific report for your exact address in South Windham, Connecticut — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that South Windham averages can't show:
We read public map data around South Windham — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the South Windham average
How we know this about South Windham
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 South Windham’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 South Windham
When does frost risk typically end in South Windham?
The last hard freeze (28°F) in South Windham typically lands around Apr 6, 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 27.
When is the first frost in South Windham?
The first hard freeze (28°F) in South Windham typically arrives around Oct 26, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 12, so the watching starts about Sep 26 — about 203 days after the spring freeze cleared.
How long is the growing season in South Windham?
Measured between 28°F hard freezes, South Windham sees about 203 frost-free days — roughly Apr 6 through Oct 26, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 27 to Oct 12, about 168 days.
Is the soil safe to grow vegetables in South Windham?
The federal record around South Windham is a meaningful one — 624 documented sites, mostly Underground Storage Tanks entries (331), the nearest Toxics Release Inventory record about 0.4 miles 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 South Windham?
From about Sep 26 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 26 (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 26. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at South Windham's scale — its 6b band and its 203-day season. Your yard writes its own version of South Windham'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 South Windham’s own scale
7 of the readings below were taken at South Windham's own scale — its own ~203-day season between 28°F freezes, the 1,994 acres it covers and 624 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- South Windham's own USDA hardiness band, zones 6bUSDA PHZM 2023
- South Windham's own 28°F hard-freeze dates, about Apr 6 and Oct 26 and the ~203-day span between themNOAA 1991–2020 Climate Normals
- 624 documented contamination sites on the federal record near South Windham, the closest Toxics Release Inventory record about 0.4 miles out from the town centreFederal environmental registers
- South Windham's boundary and the 1,994 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~203-day seasonGrowable Ground crop-matching engine
- The ecoregion at South Windham's own centroid, the Northeastern Coastal ZoneUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of South Windhamlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so South Windham's 1,994 acres read through its county's SSURGO summaryfrom Southeastern Connecticut County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Southeastern Connecticut County
- The growing challenges every Connecticut grower plans around — written at state scale, so they stay on the state guidefrom Connecticut
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Southeastern Connecticut County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among South Windham's 1,994 acreswhy one lot differs from the next →
- Which side of South Windham you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,994 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Toxics Release Inventory record about 0.4 miles 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 South Windham-wide figureread your own land →
More in Connecticut
Wider growing context
What grows across ConnecticutSouth Windham sits outside our named growing regions, so Connecticut as a whole is its closest context here.
Nearby growing guides