Aroostook County spans USDA hardiness zone 4a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Northern Maine's vast potato country — hard winters, a short intense summer, and deep glacial loams behind one of the country's great seed-potato regions. Among the crops suited to this profile: potato, kale, blueberry, and apple. The site-level story — soil, sun, drainage — decides the rest.
Aroostook County spans Maine.
Your yard isn't all of Aroostook County.
Aroostook County spans USDA zones 4a, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Aroostook County — soil, climate, flood, and parcel records. How we handle your address.
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Aroostook County — the short answer
Aroostook County: USDA zones 4a, 153 frost-free days, in Maine.
- USDA zones
- 4a
- USDA PHZM 2023, aggregated over the footprint
- Frost-free season
- 153 days
- NOAA Regional Climate Centers ACIS, 1991–2020
- Counties
- 1
- US Census TIGER/Line 2025
- Region type
- County cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. Where a region publishes no measured season, no season figure is shown.
Hardiness Zone Range
What Grows in Aroostook County
Plants matched to Aroostook County's USDA zones 4a, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of Aroostook County
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets Aroostook County’s USDA zones 4a — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across Aroostook County
The USDA soil survey maps this ground county by county. These are those records weighted by land area across one member county — this region’s own profile, not a state figure.
The ground is predominantly Spodosols, at 69% of mapped acres, followed by Inceptisols (27%), Histosols (3%) and Entisols (1%). The most extensive named soils are Howland, Monarda, and Plaisted.
27% of those acres are moderately well drained, and another 26% poorly drained, 22% well drained. Topsoil pH runs 4.2–4.8 in that county’s own record. 8% of the footprint is classed prime farmland.
Soil order
Spodosols
Drainage
Moderately well drained
Topsoil pH
4.2–4.8
Hydric soils
29%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in Aroostook County
The soil survey reads this ground county by county, and the readings above are those records summed across Aroostook County. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records27% of the mapped acres across Aroostook County are moderately well drained — roughly the middle of the drainage range. That is area-weighted across its one mapped county.
This is close to the middle most vegetables prefer: it holds enough water to carry a crop between rains without staying waterlogged. The catch is that a wet spring or a low corner can still tip it soggy.
Plant on the site as-is for most crops, but keep the lowest, slowest-draining beds for moisture-tolerant plantings.
USDA NRCS SSURGO
Surface pH
From county recordsTopsoil across Aroostook County runs pH 4.2–4.8 — acidic in the one record covering it.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Wet ground
From county recordsAbout 29% of the ground across Aroostook County is mapped as hydric — wetland — soil.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Safe to Grow Here?
What the federal record shows across Aroostook County — and how to grow with it.
Across Aroostook County's 1 county the federal record holds 979 documented sites, mostly Underground Storage Tanks (746), Brownfields (110) and Nitrate (76). The heaviest single county is Aroostook County, with 979.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to Aroostook County to see which records sit where you actually grow.
Sources Checked
Summed across the county in Aroostook County
A note from Gnorman
What an experienced grower watches for around here
In and around Aroostook County, Underground Storage Tanks runs higher than the national average — 746 sites across the county in Aroostook County. 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.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside Aroostook County
Everything above resolves to Aroostook County as a whole — a footprint spanning USDA zones 4a. Your parcel sits in exactly one of them. 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 region 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 regional average.
Your Lot vs Aroostook County Average
Aroostook County Average
- ●USDA Zones 4a, averaged across Aroostook County
- ●One soil character for all of Aroostook County
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Aroostook County's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Aroostook County
Pull a site-specific report for your exact address in Aroostook County — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Aroostook County averages can't show:
We read public map data around Aroostook County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not Aroostook County average
How we know this about Aroostook County
The boundary: a cluster of neighboring counties. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about Aroostook County
What hardiness zone is Aroostook County?
Aroostook County spans USDA hardiness zones 4a, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
What grows well in Aroostook County?
Aroostook County's conditions suit plants such as Potato, Kale, Blueberry, Apple, White Pine. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is Aroostook County defined?
Aroostook County is defined here as a curated cluster of 1 neighboring counties that share a growing character. Growing regions have no official boundary, so this footprint is our published one — every county in it is named on this page.
Which states does Aroostook County cover?
Aroostook County spans Maine. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Midcoast Maine, Casco Bay / Greater Portland, Down East Maine, Western Maine Mountains (High Peaks / Rangeley Lakes), Greater Bangor / Penobscot Valley, and Kennebec Valley (Central Maine) share at least one state with Aroostook County. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at Aroostook County’s own scale
5 of the readings below were taken at Aroostook County's own scale — the zone 4a band across its footprint and 979 documented federal contamination records across its one county, 979 of them in Aroostook County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 4a aggregated across the footprint's one countyUSDA PHZM 2023
- The boundary itself — the 1 county this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The federal contamination record over the whole footprint — 979 documented federal contamination records across its one county, 979 of them in Aroostook County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 69% Spodosols, topsoil pH 4.2–4.8, area-weighted across its one mapped countyUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 4afrom Maine
What this page can’t tell you
- Frost dates — they swing too far across a footprint this size to quote as one regional numberfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore Aroostook County
State growing guides
Counties in this region
Other growing regions across Maine
Maine's rocky-peninsula coast, where the Atlantic tempers winters into USDA zones 5b–6a and stretches the frost-free season to roughly 186–222 days — Knox County's 222-day window is the longest of any county in the state.
Coastal southern Maine around Portland and Casco Bay — the three counties of the Census Portland-South Portland metro (Cumberland, Sagadahoc, York) all share USDA hardiness zone 5b and a growing season of roughly 166 to 188 frost-free days, the ocean holding the first fall freeze off until late October.
Down East Maine spans Hancock and Washington counties along the state's easternmost coast, where a maritime-tempered USDA zone 5b holds a short frost-free season of roughly 178 to 188 days.
The only true mountain regime in Maine. Franklin County runs just a 143-day growing season in zone 4b — the coldest, shortest-season part of the state outside Aroostook — because high elevation plus valley cold-air pooling in the High Peaks and Rangeley Lakes country pushes last frosts into late May and first frosts into early September. That is a short, sharp mountain season that neither Maine's milder coast nor Aroostook's flat lowland potato country shares, and it changes what you can start from seed, when you transplant, and which long-season crops need a head start indoors.
The Penobscot Valley's settled corridor — Bangor to Old Town river ground whose measured 177-187-day seasons run a solid week past the 2-million-acre northern-forest county around it.
Central Maine's inland exception to an all-coastal map. Where the Kennebec River threads Augusta, Waterville and Gardiner, the corridor holds Zone 5b with roughly 190 frost-free days — one of the warmer pockets of Maine's continental interior, and warmer than the 4b uplands that ring it. But "continental" is the operative word: with no Atlantic moderation like a Casco Bay parcel gets, growers here trade steadier summer heat for harder radiational-frost nights that can fall well below the nominal-zone number on a clear, still spring or fall evening. Read your own cold pockets off the river — not just the corridor's headline zone.