Grand Isle County, in Vermont, sits in USDA hardiness zone 5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Growers here do well with sugar maple, apple, garlic, and blueberry — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Grand Isle County holds more than one microclimate.
Soils and elevations shift across Grand Isle County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Quick Facts
USDA Zones
5a
Last Hard Freeze (28°F)
Apr 13
County normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Nov 11
County normal — light frosts arrive a few weeks earlier
County Area
52K acres
Hardiness Zone Range
Zone maps are averages across Grand Isle County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Grand Isle County
Across Grand Isle County, the ground is predominantly Inceptisols, where Covington, Benson, and Amenia are the most extensive named soil series. The soil is generally poorly drained with a silt loam surface. Topsoil pH runs about 6.5–6.7, neutral. Rainfall drains through hydrologic group D soils.
Soil order
Inceptisols
Drainage
Poorly drained
Prime farmland
23%
Hydric soils
41%
Soil still varies lot by lot — soil types explained.
What Grows in Grand Isle County
Plants matched to Grand Isle County's USDA zones 5a — each links to its full growing profile.
Is it too late to plant in Grand Isle County?
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 16; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 11 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
Growing Challenges in Vermont
What an experienced grower plans around here — each one has a move.
Short growing season (100-130 frost-free days)
Indoor starts, fast varieties, and a cold frame on each shoulder — the Vermont formula for making 110 days feel like 150.
Rocky soils throughout the Green Mountains
Raised beds spare you the stone harvest — build up over cleared ground and plant the same weekend.
Heavy clay in the Champlain Valley
Champlain clay holds spring water late — raised or mounded beds dry out and warm up weeks earlier for planting.
For cultivar selection, pest pressure, and planting-time guidance specific to Vermont, the UVM Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Grand Isle County — and how to grow with it.
We checked the federal record across Grand Isle County — 77 documented sites across 2 of the 9 source types we track.
The most significant on record: 36 brownfield sites. Former commercial or industrial land where legacy contamination may persist.
The federal record across Grand Isle County is a modest one — a typical footprint for a growing area. Nothing here calls for alarm; it's worth knowing which recorded sites sit closest to where you grow, and each one on the map carries its type and location. If one turns out to be a near neighbor, a one-time soil test settles the question.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Severity Distribution
across Grand Isle County
Highest-Severity Sites
Know Before You Grow
- •Underground tanks can leak petroleum products. Soil testing near former gas stations is recommended.
- •Raised beds with imported soil can reduce exposure risk near brownfield sites.
Check your specific parcel in Grand Isle County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Grand Isle County Average
- ●USDA Zones 5a
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Grand Isle County
Pull a site-specific report for your exact address in Grand Isle County, Vermont — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Grand Isle County, Vermont
- USDA Hardiness Zones: 5a (USDA PHZM 2023)
- Last Hard Freeze (28°F): Apr 13 (county normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Nov 11 (county normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~212 (county normal, NOAA 1991–2020 Climate Normals)
- County Land Area: 52K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Grand Isle County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Grand Isle County, Vermont?
Grand Isle County sits in USDA hardiness zone 5a, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
Is it too late to plant in Grand Isle County?
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 16; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 11 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
When does frost risk typically end in Grand Isle County?
The last hard freeze (28°F) in Grand Isle County typically lands around Apr 13, per NOAA 1991–2020 climate normals — an earlier marker than the light-frost dates many planting charts quote. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
How long is the growing season in Grand Isle County?
Measured between 28°F hard freezes, Grand Isle County sees about 212 frost-free days — roughly Apr 13 through Nov 11, per NOAA 1991–2020 climate normals. Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
What vegetables grow in Grand Isle County?
Grand Isle County's zone 5a supports a wide range — strong performers include Sugar Maple, Apple, Garlic, Blueberry, and Kale. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Grand Isle County, really?
Officially, Grand Isle County sits in USDA zone 5a (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Grand Isle County?
The federal record around Grand Isle County shows 77 documented sites — 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.
Just moved to Grand Isle County — what should I know before planting?
Start with three facts. Grand Isle County sits in USDA zone 5a, which sets what survives winter; the last 28°F hard freeze typically clears around Apr 13, with about 212 frost-free days to work with (NOAA 1991–2020 climate normals); and 77 documented sites sit on the federal record — a typical footprint for a growing area, worth a look on the contamination map before food beds. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Grand Isle County average. Your yard writes its own version — we read soil, sun, drainage, and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Vermont's frost window, season length, and soil profile against the plant's real requirements.