Calais, Maine, sits in USDA hardiness zone 5a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
On paper, cabbage, cranberry, lavender, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in Calais, 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 Calais 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 Calais — soil, climate, flood, and parcel records. How we handle your address.
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Calais — the short answer
Calais, Maine: USDA zone 5a, about 176 days between hard freezes, across 22K acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 26
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 19
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~176
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 22K 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 5a is Calais's average, not your lot's — a low corner or a tree line moves it. Against Calais's 176-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Calais
Each reading below is measured for Calais itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredCalais runs about 176 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredCalais sits in USDA hardiness zone 5a.
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 Calais is in
Calais sits in the Acadian Plains and Hills — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Calais's own centroid rather than borrowed from Washington County.
What Grows in Calais
Every plant below cleared Calais's own zone 5a and its 176-day season. Each card opens that plant's Maine profile. How we score.
Is it too late to plant in Calais?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 29; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 26 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 19 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What's on the federal record near Calais
Closest first, within ~10 miles of Calais. Listing isn't leaking, and distance isn't exposure.
- ONEIL MOTORS & ONEIL GARAGEUnderground Storage Tanks · 1.3 mi
- LENENTINE CHEV & OLDSUnderground Storage Tanks · 1.8 mi
- PRATT CHEVY OLDS PONTIAC BUICKBrownfields · 1.8 mi
- WASHINGTON COUNTY TECH COLLEGEUnderground Storage Tanks · 2.1 mi
- EASTERN MAINE ELECTRIC POWER PLANTBrownfields · 3.0 mi
- THE LANE CONSTRUCTION CORPUnderground Storage Tanks · 3.0 mi
- CALAIS REGIONAL HOSPITALUnderground Storage Tanks · 3.5 mi
- BARNARD NURSING HOMEUnderground Storage Tanks · 3.5 mi
- CALAIS REGIONAL HOSPITALBrownfields · 3.6 mi
- TRACTOR SUPPLY COMPANY #1752Brownfields · 3.6 mi
- WALMART STORE 2178Brownfields · 3.7 mi
- CALAIS MAINWAYUnderground Storage Tanks · 3.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Calais'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 Calais.
Sources Checked
within ~10 miles of Calais
Severity Distribution
within ~10 miles of Calais
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Calais, Underground Storage Tanks runs higher than the national average — 57 sites within ~10 miles of Calais. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Calais
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 Calais average
Your land is one point inside Calais
Everything above resolves to Calais as a whole — one PHZM band and one 28°F frost record, read across 22K 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 city 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 Calais Average
Calais Average
- ●USDA Zones 5a, averaged across Calais
- ●One soil character for all of Calais
- ●Frost dates read at Calais's scale: Apr 26 to Oct 19
YOUR Parcel
- ✓Your exact zone, not Calais's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Calais
Pull a site-specific report for your exact address in Calais, Maine — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Calais averages can't show:
We read public map data around Calais — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Calais average
How we know this about Calais
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Calais’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 city grain anywhere on this page — there is no city-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 Calais
When does frost risk typically end in Calais?
The last hard freeze (28°F) in Calais typically lands around Apr 26, 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 May 17.
When is the first frost in Calais?
The first hard freeze (28°F) in Calais typically arrives around Oct 19, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 5, so the watching starts about Sep 19 — about 176 days after the spring freeze cleared.
How long is the growing season in Calais?
Measured between 28°F hard freezes, Calais sees about 176 frost-free days — roughly Apr 26 through Oct 19, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 17 to Oct 5, about 141 days.
Is the soil safe to grow vegetables in Calais?
The federal record around Calais is a meaningful one — 88 documented sites, mostly Underground Storage Tanks entries (57), the nearest Underground Storage Tanks record about 1.3 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 Calais?
From about Sep 19 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 19 (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 19. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Calais's scale — its 5a band and its 176-day season. Your yard writes its own version of Calais'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 Calais’s own scale
6 of the readings below were taken at Calais's own scale — its own ~176-day season between 28°F freezes, the 21,967 acres it covers and 88 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Calais's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Calais's own 28°F hard-freeze dates, about Apr 26 and Oct 19 and the ~176-day span between themNOAA 1991–2020 Climate Normals
- 88 documented contamination sites on the federal record near Calais, the closest Underground Storage Tanks record about 1.3 miles out from the town centreFederal environmental registers
- Calais's boundary and the 21,967 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~176-day seasonGrowable Ground crop-matching engine
- The ecoregion at Calais's own centroid, the Acadian Plains and HillsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Calais's 21,967 acres read through its county's SSURGO summaryfrom Washington County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Washington County
- The growing challenges every Maine grower plans around — written at state scale, so they stay on the state guidefrom Maine
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Washington County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Calais's 21,967 acreswhy one lot differs from the next →
- Which side of Calais you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 21,967 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 1.3 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 Calais-wide figureread your own land →
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