Grand Isle, Maine, sits in USDA hardiness zone 4a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
The conditions favor cabbage, cranberry, turkish rocket, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Even in Grand Isle, 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 Grand Isle 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 Grand Isle — soil, climate, flood, and parcel records. How we handle your address.
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Grand Isle — the short answer
Grand Isle, Maine: USDA zone 4a, about 155 days between hard freezes, across 396 acres of town.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 4
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~155
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 396 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 4a is Grand Isle's average, not your lot's — a low corner or a tree line moves it. Against Grand Isle's 155-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Grand Isle
Each reading below is measured for Grand Isle itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredGrand Isle runs about 155 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
MeasuredGrand Isle sits in USDA hardiness zone 4a.
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 Grand Isle is in
Grand Isle sits in the Acadian Plains and Hills — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Grand Isle's own centroid rather than borrowed from Aroostook County.
What Grows in Grand Isle
Every plant below cleared Grand Isle's own zone 4a and its 155-day season. Each card opens that plant's Maine profile. How we score.
Is it too late to plant in Grand Isle?
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 Apr 6; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 4 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 6 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
What's on the federal record near Grand Isle
Closest first, within ~10 miles of Grand Isle. Listing isn't leaking, and distance isn't exposure.
- VICTORS IRVINGUnderground Storage Tanks · 1900 ft
- ARW 900Nitrate · 1.2 mi
- PARENT, SYLVIAUnderground Storage Tanks · 2.1 mi
- SOUCYS GARAGEUnderground Storage Tanks · 2.1 mi
- LAWRENCE PARENT GENERAL STOREUnderground Storage Tanks · 2.1 mi
- GRAND ISLE TOWN OFUnderground Storage Tanks · 2.1 mi
- ARW 901Nitrate · 4.0 mi
- VN SPECIALUnderground Storage Tanks · 4.4 mi
- MADAWASKA TOWN SHEDUnderground Storage Tanks · 4.7 mi
- NOTRE DAME GARAGEUnderground Storage Tanks · 5.2 mi
- GYMUnderground Storage Tanks · 5.2 mi
- MAINE DEPARTMENT OF TRANSPORTATIONBrownfields · 5.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Grand Isle'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 Grand Isle.
Total Sites
68
within ~10 miles of Grand Isle
Risk Level
Moderate
Highest-severity
3 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Grand Isle
Severity Distribution
within ~10 miles of Grand Isle
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Grand Isle, Underground Storage Tanks runs higher than the national average — 50 sites within ~10 miles of Grand Isle. 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 Grand Isle
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 Grand Isle average
Your land is one point inside Grand Isle
Everything above resolves to Grand Isle as a whole — one PHZM band and one 28°F frost record, read across 396 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 Grand Isle Average
Grand Isle Average
- ●USDA Zones 4a, averaged across Grand Isle
- ●One soil character for all of Grand Isle
- ●Frost dates read at Grand Isle's scale: May 4 to Oct 6
YOUR Parcel
- ✓Your exact zone, not Grand Isle's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Grand Isle
Pull a site-specific report for your exact address in Grand Isle, Maine — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Grand Isle averages can't show:
We read public map data around Grand Isle — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Grand Isle average
How we know this about Grand Isle
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 Grand Isle’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 Grand Isle
When does frost risk typically end in Grand Isle?
The last hard freeze (28°F) in Grand Isle typically lands around May 4, 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 25.
When is the first frost in Grand Isle?
The first hard freeze (28°F) in Grand Isle typically arrives around Oct 6, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 22, so the watching starts about Sep 6 — about 155 days after the spring freeze cleared.
How long is the growing season in Grand Isle?
Measured between 28°F hard freezes, Grand Isle sees about 155 frost-free days — roughly May 4 through Oct 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 25 to Sep 22, about 120 days.
Is the soil safe to grow vegetables in Grand Isle?
The federal record around Grand Isle shows 68 documented sites, mostly Underground Storage Tanks entries (50), the nearest Underground Storage Tanks record about 0.4 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Grand Isle?
From about Sep 6 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 6 (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 6. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Grand Isle's scale — its 4a band and its 155-day season. Your yard writes its own version of Grand Isle'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 Grand Isle’s own scale
6 of the readings below were taken at Grand Isle's own scale — its own ~155-day season between 28°F freezes, the 396 acres it covers and 68 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Grand Isle's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Grand Isle's own 28°F hard-freeze dates, about May 4 and Oct 6 and the ~155-day span between themNOAA 1991–2020 Climate Normals
- 68 documented contamination sites on the federal record near Grand Isle, the closest Underground Storage Tanks record about 0.4 miles out from the town centreFederal environmental registers
- Grand Isle's boundary and the 396 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~155-day seasonGrowable Ground crop-matching engine
- The ecoregion at Grand Isle'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 Grand Isle's 396 acres read through its county's SSURGO summaryfrom Aroostook County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Aroostook 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 Aroostook County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Grand Isle's 396 acreswhy one lot differs from the next →
- Which side of Grand Isle you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 396 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks 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 Grand Isle-wide figureread your own land →
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