Old Mystic, Connecticut, sits in USDA hardiness zone 7a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
A short list that earns its place here — cabbage, hazelnut, california poppy, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Old Mystic, 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 Old Mystic 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 Old Mystic — soil, climate, flood, and parcel records. How we handle your address.
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Old Mystic — the short answer
Old Mystic, Connecticut: USDA zone 7a, about 225 days between hard freezes, across 3K acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 5
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~225
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 3K 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 7a is Old Mystic's average, not your lot's — a low corner or a tree line moves it. Against Old Mystic's 225-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Old Mystic
Each reading below is measured for Old Mystic itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredOld Mystic runs about 225 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
MeasuredOld Mystic sits in USDA hardiness zone 7a.
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 Old Mystic is in
Old Mystic sits in the Northeastern Coastal Zone — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Old Mystic's own centroid rather than borrowed from Southeastern Connecticut Planning Region.
What Grows in Old Mystic
Every plant below cleared Old Mystic's own zone 7a and its 225-day season. Each card opens that plant's Connecticut profile. How we score.
Is it too late to plant in Old Mystic?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 8; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 5 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 16 — long-season crops need about 90 days of runway, quick greens only 30. Here the season winds down slowly: late sowings, a real autumn harvest, and garlic in the ground before the first hard freeze.
Documented around Old Mystic
Spotted lanternfly documented 12 miles from Old Mystic, first recorded 2022. What to watch for.
What's on the federal record near Old Mystic
Closest first, within ~10 miles of Old Mystic. Listing isn't leaking, and distance isn't exposure.
- ANN AVENUE PUMP STATIONUnderground Storage Tanks · 1000 ft
- COASTAL PETROLEUM CORPORATION d/b/a Haley Brook MobilUnderground Storage Tanks · 2300 ft
- RIVERSIDE FOREIGN MOTORS INCBrownfields · 0.7 mi
- WELLES GARAGEBrownfields · 0.7 mi
- GROTON MAINTENANCE FACILITYUnderground Storage Tanks · 0.8 mi
- MYSTIC EDUCATION CENTERUnderground Storage Tanks · 0.9 mi
- WHITFORD MARINE SERVBrownfields · 0.9 mi
- DOTBrownfields · 1.0 mi
- COMRIES LANDSCAPE SERVICE INCUnderground Storage Tanks · 1.0 mi
- GROTON EDUCATION DEPARTMENTBrownfields · 1.0 mi
- COLONIAL TIREUnderground Storage Tanks · 1.1 mi
- MEROCEL FACILITYToxics Release Inventory · 1.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Old Mystic'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 Old Mystic.
Sources Checked
within ~10 miles of Old Mystic
Severity Distribution
within ~10 miles of Old Mystic
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Old Mystic, Superfund runs higher than the national average — 16 sites within ~10 miles of Old Mystic. 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.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Old Mystic
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 Old Mystic average
Your land is one point inside Old Mystic
Everything above resolves to Old Mystic as a whole — one PHZM band and one 28°F frost record, read across 3K 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 Old Mystic Average
Old Mystic Average
- ●USDA Zones 7a, averaged across Old Mystic
- ●One soil character for all of Old Mystic
- ●Frost dates read at Old Mystic's scale: Apr 5 to Nov 16
YOUR Parcel
- ✓Your exact zone, not Old Mystic's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Old Mystic
Pull a site-specific report for your exact address in Old Mystic, Connecticut — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Old Mystic averages can't show:
We read public map data around Old Mystic — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Old Mystic average
How we know this about Old Mystic
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 Old Mystic’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 Old Mystic
When does frost risk typically end in Old Mystic?
The last hard freeze (28°F) in Old Mystic typically lands around Apr 5, 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 26.
When is the first frost in Old Mystic?
The first hard freeze (28°F) in Old Mystic typically arrives around Nov 16, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 2, so the watching starts about Oct 17 — about 225 days after the spring freeze cleared.
How long is the growing season in Old Mystic?
Measured between 28°F hard freezes, Old Mystic sees about 225 frost-free days — roughly Apr 5 through Nov 16, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 26 to Nov 2, about 190 days.
Is the soil safe to grow vegetables in Old Mystic?
The federal record around Old Mystic is a meaningful one — 947 documented sites, mostly Underground Storage Tanks entries (511), the nearest Underground Storage Tanks record about 0.2 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 Old Mystic?
From about Oct 17 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 Nov 16 (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 Nov 16. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Old Mystic's scale — its 7a band and its 225-day season. Your yard writes its own version of Old Mystic'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 Old Mystic’s own scale
7 of the readings below were taken at Old Mystic's own scale — its own ~225-day season between 28°F freezes, the 2,746 acres it covers and 947 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Old Mystic's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Old Mystic's own 28°F hard-freeze dates, about Apr 5 and Nov 16 and the ~225-day span between themNOAA 1991–2020 Climate Normals
- 947 documented contamination sites on the federal record near Old Mystic, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Old Mystic's boundary and the 2,746 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~225-day seasonGrowable Ground crop-matching engine
- The ecoregion at Old Mystic's own centroid, the Northeastern Coastal ZoneUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Old Mysticlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Old Mystic's 2,746 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 Old Mystic's 2,746 acreswhy one lot differs from the next →
- Which side of Old Mystic you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,746 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.2 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 Old Mystic-wide figureread your own land →
More in Connecticut
Wider growing context
What grows across ConnecticutOld Mystic sits outside our named growing regions, so Connecticut as a whole is its closest context here.
Nearby growing guides